XF86SUP.SYS
Suhaib Siddiqi
ssiddiqi@inspirepharm.com
Fri Nov 12 09:26:00 GMT 1999
Here is a document on XF86 Video Mode. It will help you understand
how it does.
Please also have a look at the attached "Design" document. It
explains
basic principles of XF86 design.
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XFree86 Video Timings HOWTO
Eric S. Raymond <esr@thyrsus.com>
Version 3.0, 8 Aug 1997
Abstract
How to compose a mode line for your card/monitor combination
under
XFree86. The XFree86 distribution now includes good facilities
for
configuring most standard combinations; this document is mainly
useful if you are tuning a custom mode line for a
high-performance
monitor or very unusual hardware. It may also help you in
using
xvidtune to tweak a standard mode that is not quite right for
your
monitor.
1. Disclaimer
You use the material herein SOLELY AT YOUR OWN RISK. It is possible
to harm
both your monitor and yourself when driving it outside the
manufacturer's
specs. Read Overdriving Your Monitor (section 11., page 1) for
detailed cau-
tions. Any damages to you or your monitor caused by overdriving it
are your
problem.
The most up-to-date version of this HOWTO can be found at the Linux
Documen-
tation Project <URL: http://sunsite.unc.edu/LDP > web page.
Please direct comments, criticism, and suggestions for improvement
to
esr@snark.thyrsus.com. Please do not send email pleading for a magic
solution
to your special monitor problem, as doing so will only burn up my
time and
frustrate you -- everything I know about the subject is already in
here.
2. Introduction
The XFree86 server allows users to configure their video subsystem
and thus
encourages best use of existing hardware. This tutorial is intended
to help
you learn how to generate your own timing numbers to make optimum
use of your
video card and monitor.
We'll present a method for getting something that works, and then
show you
how you can experiment starting from that base to develop settings
that opti-
mize for your taste.
Starting with XFree86 3.2, XFree86 provides an XF86Setup(1) program
that
makes it easy to generate a working monitor mode interactively,
without mess-
ing with video timing number directly. So you shouldn't actually
need to
calculate a base monitor mode in most cases. Unfortunately,
XF86Setup(1) has
some limitations; it only knows about standard video modes up to
1280x1024.
If you have a very high-performance monitor capable of 1600x1200 or
more you
will still have to compute your base monitor mode yourself.
Recent versions of XFree86 provide a tool called xvidtune(1) which
you will
probably find quite useful for testing and tuning monitor modes. It
begins
with a gruesome warning about the possible consequences of mistakes
with it.
If you pay careful attention to this document and learn what is
behind the
pretty numbers in xvidtune's boxes, you will become able to use
xvidtune
effectively and with confidence.
If you already have a mode that almost works (in particular, if one
of prede-
fined VESA modes gives you a stable display but one that's displaced
right or
left, or too small, or too large) you can go straight to the section
on Fix-
ing Problems with the Image (section 14., page 1). This will
enlighten you
on ways to tweak the timing numbers to achieve particular effects.
If you have xvidtune(1), you'll be able to test new modes on the
fly, without
modifying your X configuration files or even rebooting your X
server. Other-
wise, XFree86 allows you to hot-key between different modes defined
in Xcon-
fig (see XFree86.man for details). Use this capabilty to save
yourself has-
sles! When you want to test a new mode, give it a unique mode label
and add
it to the end of your hot-key list. Leave a known-good mode as the
default
to fall back on if the test mode doesn't work.
3. How Video Displays Work
Knowing how the display works is essential to understanding what
numbers to
put in the various fields in the file Xconfig. Those values are
used in the
lowest levels of controlling the display by the XFree86 server.
The display generates a picture from a series of dots. The dots are
arranged
from left to right to form lines. The lines are arranged from top
to bottom
to form the picture. The dots emit light when they are struck by
the elec-
tron beam inside the display. To make the beam strike each dot for
an equal
amount of time, the beam is swept across the display in a constant
pattern.
The pattern starts at the top left of the screen, goes across the
screen to
the right in a straight line, and stops temporarily on the right
side of the
screen. Then the beam is swept back to the left side of the
display, but
down one line. The new line is swept from left to right just as the
first
line was. This pattern is repeated until the bottom line on the
display has
been swept. Then the beam is moved from the bottom right corner of
the dis-
play to the top left corner, and the pattern is started over again.
There is one variation of this scheme known as interlacing: here
only every
second line is swept during one half-frame and the others are filled
in in
during a second half-frame.
Starting the beam at the top left of the display is called the
beginning of a
frame. The frame ends when the beam reaches the the top left corner
again as
it comes from the bottom right corner of the display. A frame is
made up of
all of the lines the beam traced from the top of the display to the
bottom.
If the electron beam were on all of the time it was sweeping through
the
frame, all of the dots on the display would be illuminated. There
would be
no black border around the edges of the display. At the edges of
the display
the picture would become distorted because the beam is hard to
control there.
To reduce the distortion, the dots around the edges of the display
are not
illuminated by the beam even though the beam may be pointing at
them. The
viewable area of the display is reduced this way.
Another important thing to understand is what becomes of the beam
when no
spot is being painted on the visible area. The time the beam would
have been
illuminating the side borders of the display is used for sweeping
the beam
back from the right edge to the left and moving the beam down to the
next
line. The time the beam would have been illuminating the top and
bottom bor-
ders of the display is used for moving the beam from the
bottom-right corner
of the display to the top-left corner.
The adapter card generates the signals which cause the display to
turn on the
electron beam at each dot to generate a picture. The card also
controls when
the display moves the beam from the right side to the left and down
a line by
generating a signal called the horizontal sync (for synchronization)
pulse.
One horizontal sync pulse occurs at the end of every line. The
adapter also
generates a vertical sync pulse which signals the display to move
the beam to
the top-left corner of the display. A vertical sync pulse is
generated near
the end of every frame.
The display requires that there be short time periods both before
and after
the horizontal and vertical sync pulses so that the position of the
electron
beam can stabilize. If the beam can't stabilize, the picture will
not be
steady.
In a later section, we'll come back to these basics with
definitions, formu-
las and examples to help you use them.
4. Basic Things to Know about your Display and Adapter
There are some fundamental things you need to know before hacking an
Xconfig
entry. These are:
o your monitor's horizontal and vertical sync frequency options
o your video adapter's driving clock frequency, or "dot clock"
o your monitor's bandwidth
The monitor sync frequencies:
The horizontal sync frequency is just the number of times per second
the mon-
itor can write a horizontal scan line; it is the single most
important
statistic about your monitor. The vertical sync frequency is the
number of
times per second the monitor can traverse its beam vertically.
Sync frequencies are usually listed on the specifications page of
your moni-
tor manual. The vertical sync frequency number is typically
calibrated in Hz
(cycles per second), the horizontal one in KHz (kilocycles per
second). The
usual ranges are between 50 and 150Hz vertical, and between 31 and
135KHz
horizontal.
If you have a multisync monitor, these frequencies will be given as
ranges.
Some monitors, especially lower-end ones, have multiple fixed
frequencies.
These can be configured too, but your options will be severely
limited by the
built-in monitor characteristics. Choose the highest frequency pair
for best
resolution. And be careful --- trying to clock a fixed-frequency
monitor at
a higher speed than it's designed for can easily damage it.
Earlier versions of this guide were pretty cavalier about
overdriving multi-
sync monitors, pushing them past their nominal highest vertical sync
fre-
quency in order to get better performance. We have since had more
reasons
pointed out to us for caution on this score; we'll cover those under
Over-
driving Your Monitor (section 11., page 1) below.
The card driving clock frequency:
Your video adapter manual's spec page will usually give you the
card's dot
clock (that is, the total number of pixels per second it can write
to the
screen). If you don't have this information, the X server will get
it for
you. Even if your X locks up your monitor, it will emit a line of
clock and
other info to standard output. If you redirect this to a file, it
should be
saved even if you have to reboot to get your console back. (Recent
versions
of the X servers allsupport a --probeonly option that prints out
this infor-
mation and exits without actually starting up X or changing the
video mode.)
Your X startup message should look something like one of the
following exam-
ples:
If you're using XFree86:
Xconfig: /usr/X11R6/lib/X11/Xconfig
(**) stands for supplied, (--) stands for probed/default values
(**) Mouse: type: MouseMan, device: /dev/ttyS1, baudrate: 9600
Warning: The directory "/usr/andrew/X11fonts" does not exist.
Entry deleted from font path.
(**) FontPath set to
"/usr/lib/X11/fonts/misc/,/usr/lib/X11/fonts/75dpi/"
(--) S3: card type: 386/486 localbus
(--) S3: chipset: 924
---
Chipset -- this is the exact chip type; an early mask of
the 86C911
(--) S3: chipset driver: s3_generic
(--) S3: videoram: 1024k
-----
Size of on-board frame-buffer RAM
(**) S3: clocks: 25.00 28.00 40.00 3.00 50.00 77.00
36.00 45.00
(**) S3: clocks: 0.00 0.00 79.00 31.00 94.00 65.00
75.00 71.00
---------------------------------------------
---------
Possible driving frequencies in
MHz
(--) S3: Maximum allowed dot-clock: 110MHz
------
Bandwidth
(**) S3: Mode "1024x768": mode clock = 79.000, clock used =
79.000
(--) S3: Virtual resolution set to 1024x768
(--) S3: Using a banksize of 64k, line width of 1024
(--) S3: Pixmap cache:
(--) S3: Using 2 128-pixel 4 64-pixel and 8 32-pixel slots
(--) S3: Using 8 pages of 768x255 for font caching
If you're using SGCS or X/Inside X:
WGA: 86C911 (mem: 1024k clocks: 25 28 40 3 50 77 36 45 0 0 79
31 94 65 75 71)
--- ------ ----- -------------------------------
-------------
| | | Possible driving
frequencies in MHz
| | +-- Size of on-board frame-buffer RAM
| +-- Chip type
+-- Server type
Note: do this with your machine unloaded (if at all possible).
Because X is
an application, its timing loops can collide with disk activity,
rendering
the numbers above inaccurate. Do it several times and watch for the
numbers
to stabilize; if they don't, start killing processes until they do.
SVr4
users: the mousemgr process is particularly likely to mess you up.
In order to avoid the clock-probe inaccuracy, you should clip out
the clock
timings and put them in your Xconfig as the value of the Clocks
property ---
this suppresses the timing loop and gives X an exact list of the
clock values
it can try. Using the data from the example above:
wga
Clocks 25 28 40 3 50 77 36 45 0 0 79 31 94 65 75 71
On systems with a highly variable load, this may help you avoid
mysterious X
startup failures. It's possible for X to come up, get its timings
wrong due
to system load, and then not be able to find a matching dot clock in
its con-
fig database --- or find the wrong one!
4.1 The monitor's video bandwidth:
If you're running XFree86, your server will probe your card and tell
you what
your highest-available dot clock is.
Otherwise, your highest available dot clock is approximately the
monitor's
video bandwidth. There's a lot of give here, though --- some
monitors can
run as much as 30% over their nominal bandwidth. The risks here
have to do
with exceeding the monitor's rated vertical-sync frequency; we'll
discuss
them in detail below.
Knowing the bandwidth will enable you to make more intelligent
choices
between possible configurations. It may affect your display's
visual quality
(especially sharpness for fine details).
Your monitor's video bandwidth should be included on the manual's
spec page.
If it's not, look at the monitor's higest rated resolution. As a
rule of
thumb, here's how to translate these into bandwidth estimates (and
thus into
rough upper bounds for the dot clock you can use):
640x480 25
800x600 36
1024x768 65
1024x768 interlaced 45
1280x1024 110
1600x1200 185
BTW, there's nothing magic about this table; these numbers are just
the low-
est dot clocks per resolution in the standard XFree86 Modes database
(except
for the last, which I interpolated). The bandwidth of your monitor
may actu-
ally be higher than the minimum needed for its top resolution, so
don't be
afraid to try a dot clock a few MHz higher.
Also note that bandwidth is seldom an issue for dot clocks under
65MHz or so.
With an SVGA card and most hi-res monitors, you can't get anywhere
near the
limit of your monitor's video bandwidth. The following are
examples:
Brand Video Bandwidth
---------- ---------------
NEC 4D 75Mhz
Nano 907a 50Mhz
Nano 9080i 60Mhz
Mitsubishi HL6615 110Mhz
Mitsubishi Diamond Scan 100Mhz
IDEK MF-5117 65Mhz
IOCOMM Thinksync-17 CM-7126 136Mhz
HP D1188A 100Mhz
Philips SC-17AS 110Mhz
Swan SW617 85Mhz
Viewsonic 21PS 185Mhz
Even low-end monitors usually aren't terribly bandwidth-constrained
for their
rated resolutions. The NEC Multisync II makes a good example --- it
can't
even display 800x600 per its spec. It can only display 800x560.
For such
low resolutions you don't need high dot clocks or a lot of
bandwidth; proba-
bly the best you can do is 32Mhz or 36Mhz, both of them are still
not too far
from the monitor's rated video bandwidth of 30Mhz.
At these two driving frequencies, your screen image may not be as
sharp as it
should be, but definitely of tolerable quality. Of course it would
be nicer
if NEC Multisync II had a video bandwidth higher than, say, 36Mhz.
But this
is not critical for common tasks like text editing, as long as the
difference
is not so significant as to cause severe image distortion (your eyes
would
tell you right away if this were so).
4.2 What these control:
The sync frequency ranges of your monitor, together with your video
adapter's
dot clock, determine the ultimate resolution that you can use. But
it's up
to the driver to tap the potential of your hardware. A superior
hardware
combination without an equally competent device driver is a waste of
money.
On the other hand, with a versatile device driver but less capable
hardware,
you can push the hardware's envelope a little. This is the design
philosophy
of XFree86.
5. Interpreting the Basic Specifications
This section explains what the specifications above mean, and some
other
things you'll need to know. First, some definitions. Next to each
in parens
is the variable name we'll use for it when doing calculations
horizontal sync frequency (HSF)
Horizontal scans per second (see above).
vertical sync frequency (VSF)
Vertical scans per second (see above). Mainly important
as the
upper limit on your refresh rate.
dot clock (DCF)
More formally, `driving clock frequency'; The frequency
of the
crystal or VCO on your adaptor --- the maximum
dots-per-second it
can emit.
video bandwidth (VB)
The highest frequency you can feed into your monitor's
video
input and still expect to see anything discernible. If
your adap-
tor produces an alternating on/off pattern, its lowest
frequency
is half the DCF, so in theory bandwidth starts making
sense at
DCF/2. For tolerately crisp display of fine details in
the video
image, however, you don't want it much below your
highest DCF,
and preferably higher.
frame length (HFL, VFL)
Horizontal frame length (HFL) is the number of dot-clock
ticks
needed for your monitor's electron gun to scan one
horizontal
line, including the inactive left and right borders.
Vertical
frame length (VFL) is the number of scan lines in the
entire
image, including the inactive top and bottom borders.
screen refresh rate (RR)
The number of times per second your screen is repainted
(this is
also called "frame rate"). Higher frequencies are
better, as
they reduce flicker. 60Hz is good, VESA-standard 72Hz
is better.
Compute it as
RR = DCF / (HFL * VFL)
Note that the product in the denominator is not the same
as the
monitor's visible resolution, but typically somewhat
larger.
We'll get to the details of this below.
The rates for which interlaced modes are usually
specified (like
87Hz interlaced) are actually the half-frame rates: an
entire
screen seems to have about that flicker frequency for
typical
displays, but every single line is refreshed only half
as often.
For calculation purposes we reckon an interlaced display
at its
full-frame (refresh) rate, i.e. 43.5Hz. The quality of
an inter-
laced mode is better than that of a non-interlaced mode
with the
same full-frame rate, but definitely worse then the
non-inter-
laced one corresponding to the half-frame rate.
5.1 About Bandwidth:
Monitor makers like to advertise high bandwidth because it
constrains the
sharpness of intensity and color changes on the screen. A high
bandwidth
means smaller visible details.
Your monitor uses electronic signals to present an image to your
eyes. Such
signals always come in in wave form once they are converted into
analog form
from digitized form. They can be considered as combinations of many
simpler
wave forms each one of which has a fixed frequency, many of them are
in the
Mhz range, eg, 20Mhz, 40Mhz, or even 70Mhz. Your monitor video
bandwidth is,
effectively, the highest-frequency analog signal it can handle
without dis-
tortion.
For our purposes, bandwidth is mainly important as an approximate
cutoff
point for the highest dot clock you can use.
5.2 Sync Frequencies and the Refresh Rate:
Each horizontal scan line on the display is just the visible portion
of a
frame-length scan. At any instant there is actually only one dot
active on
the screen, but with a fast enough refresh rate your eye's
persistence of
vision enables you to "see" the whole image.
Here are some pictures to help:
_______________________
| | The horizontal sync frequency
|->->->->->->->->->->-> | is the number of times per
| )| second that the monitor's
|<-----<-----<-----<--- | electron beam can trace
| | a pattern like this
| |
| |
| |
|_______________________|
_______________________
| ^ | The vertical sync frequency
| ^ | | is the number of times per
| | v | second that the monitor's
| ^ | | electron beam can trace
| | | | a pattern like this
| ^ | |
| | v |
| ^ | |
|_______|_v_____________|
Remember that the actual raster scan is a very tight zigzag pattern;
that is,
the beam moves left-right and at the same time up-down.
Now we can see how the dot clock and frame size relates to refresh
rate. By
definition, one hertz (hz) is one cycle per second. So, if your
horizontal
frame length is HFL and your vertical frame length is VFL, then to
cover the
entire screen takes (HFL * VFL) ticks. Since your card emits DCF
ticks per
second by definition, then obviously your monitor's electron gun(s)
can sweep
the screen from left to right and back and from bottom to top and
back DCF /
(HFL * VFL) times/sec. This is your screen's refresh rate, because
it's how
many times your screen can be updated (thus refreshed) per second!
You need to understand this concept to design a configuration which
trades
off resolution against flicker in whatever way suits your needs.
For those of you who handle visuals better than text, here is one:
RR VB
| min HSF max HSF |
| | R1 R2 | |
max VSF -+----|------------/----------/---|------+----- max VSF
| |:::::::::::/::::::::::/:::::\ |
| \::::::::::/::::::::::/:::::::\ |
| |::::::::/::::::::::/:::::::::| |
| |:::::::/::::::::::/::::::::::\ |
| \::::::/::::::::::/::::::::::::\ |
| \::::/::::::::::/::::::::::::::| |
| |::/::::::::::/:::::::::::::::| |
| \/::::::::::/:::::::::::::::::\|
| /\:::::::::/:::::::::::::::::::|
| / \:::::::/::::::::::::::::::::|\
| / |:::::/:::::::::::::::::::::| |
| / \::::/::::::::::::::::::::::| \
min VSF -+----/-------\--/-----------------------|--\--- min
VSF
| / \/ | \
+--/----------/\------------------------+----\- DCF
R1 R2 \ | \
min HSF | max HSF
VB
This is a generic monitor mode diagram. The x axis of the diagram
shows the
clock rate (DCF), the y axis represents the refresh rate (RR). The
filled
region of the diagram describes the monitor's capabilities: every
point
within this region is a possible video mode.
The lines labeled `R1' and `R2' represent a fixed resolutions (such
as
640x480); they are meant to illustrate how one resolution can be
realized by
many different combinations of dot clock and refresh rate. The R2
line would
represent a higher resolution than R1.
The top and bottom boundaries of the permitted region are simply
horizontal
lines representing the limiting values for the vertical sync
frequency. The
video bandwidth is an upper limit to the clock rate and hence is
represented
by a vertical line bounding the capability region on the right.
Under Plotting Monitor Capabilities (section 15., page 1)) you'll
find a pro-
gram that will help you plot a diagram like this (but much nicer,
with X
graphics) for your individual monitor. That section also discusses
the
interesting part; the derivation of the boundaries resulting from
the limits
on the horizontal sync frequency.
6. Tradeoffs in Configuring your System
Another way to look at the formula we derived above is
DCF = RR * HFL * VFL
That is, your dot clock is fixed. You can use those dots per second
to buy
either refresh rate, horizontal resolution, or vertical resolution.
If one
of those increases, one or both of the others must decrease.
Note, though, that your refresh rate cannot be greater than the
maximum ver-
tical sync frequency of your monitor. Thus, for any given monitor
at a given
dot clock, there is a minimum product of frame lengths below which
you can't
force it.
In choosing your settings, remember: if you set RR too low, you will
get
mugged by screen flicker.
You probably do not want to pull your refresh rate below 60Hz. This
is the
flicker rate of fluorescent lights; if you're sensitive to those,
you need to
hang with 72Hz, the VESA ergonomic standard.
Flicker is very eye-fatiguing, though human eyes are adaptable and
peoples'
tolerance for it varies widely. If you face your monitor at a 90%
viewing
angle, are using a dark background and a good contrasting color for
fore-
ground, and stick with low to medium intensity, you *may* be
comfortable at
as little as 45Hz.
The acid test is this: open a xterm with pure white back-ground and
black
foreground using xterm -bg white -fg black and make it so large as
to cover
the entire viewable area. Now turn your monitor's intensity to 3/4
of its
maximum setting, and turn your face away from the monitor. Try
peeking at
your monitor sideways (bringing the more sensitive peripheral-vision
cells
into play). If you don't sense any flicker or if you feel the
flickering is
tolerable, then that refresh rate is fine with you. Otherwise you
better
configure a higher refresh rate, because that semi-invisible flicker
is going
to fatigue your eyes like crazy and give you headaches, even if the
screen
looks OK to normal vision.
For interlaced modes, the amount of flicker depends on more factors
such as
the current vertical resolution and the actual screen contents. So
just
experiment. You won't want to go much below about 85Hz half frame
rate,
though.
So let's say you've picked a minimum acceptable refresh rate. In
choosing
your HFL and VFL, you'll have some room for maneuver.
7. Memory Requirements
Available frame-buffer RAM may limit the resolution you can achieve
on color
or gray-scale displays. It probably isn't a factor on displays that
have
only two colors, white and black with no shades of gray in between.
For 256-color displays, a byte of video memory is required for each
visible
dot to be shown. This byte contains the information that determines
what mix
of red, green, and blue is generated for its dot. To get the amount
of mem-
ory required, multiply the number of visible dots per line by the
number of
visible lines. For a display with a resolution of 800x600, this
would be 800
x 600 = 480,000, which is the number of visible dots on the display.
This is
also, at one byte per dot, the number of bytes of video memory that
are nec-
essary on your adapter card.
Thus, your memory requirement will typically be (HR * VR)/1024
Kbytes of
VRAM, rounded up. If you have more memory than strictly required,
you'll
have extra for virtual-screen panning.
However, if you only have 512K on board, then you can't use this
resolution.
Even if you have a good monitor, without enough video RAM, you can't
take
advantage of your monitor's potential. On the other hand, if your
SVGA has
one meg, but your monitor can display at most 800x600, then high
resolution
is beyond your reach anyway (see Using Interlaced Modes (section
12., page 1)
for a possible remedy).
Don't worry if you have more memory than required; XFree86 will make
use of
it by allowing you to scroll your viewable area (see the Xconfig
file docu-
mentation on the virtual screen size parameter). Remember also that
a card
with 512K bytes of memory really doesn't have 512,000 bytes
installed, it has
512 x 1024 = 524,288 bytes.
If you're running SGCS X (now called X/Inside) using an S3 card, and
are
willing to live with 16 colors (4 bits per pixel), you can set depth
4 in
Xconfig and effectively double the resolution your card can handle.
S3
cards, for example, normally do 1024x768x256. You can make them do
1280x1024x16 with depth 4.
8. Computing Frame Sizes
Warning: this method was developed for multisync monitors. It will
probably
work with fixed-frequency monitors as well, but no guarantees!
Start by dividing DCF by your highest available HSF to get a
horizontal frame
length.
For example; suppose you have a Sigma Legend SVGA with a 65MHz dot
clock, and
your monitor has a 55KHz horizontal scan frequency. The quantity
(DCF / HSF)
is then 1181 (65MHz = 65000KHz; 65000/55 = 1181).
Now for our first bit of black magic. You need to round this figure
to the
nearest multiple of 8. This has to do with the VGA hardware
controller used
by SVGA and S3 cards; it uses an 8-bit register, left-shifted 3
bits, for
what's really an 11-bit quantity. Other card types such as ATI
8514/A may
not have this requirement, but we don't know and the correction
can't hurt.
So round the usable horizontal frame length figure down to 1176.
This figure (DCF / HSF rounded to a multiple of 8) is the minimum
HFL you can
use. You can get longer HFLs (and thus, possibly, more horizontal
dots on
the screen) by setting the sync pulse to produce a lower HSF. But
you'll pay
with a slower and more visible flicker rate.
As a rule of thumb, 80% of the horizontal frame length is available
for hori-
zontal resolution, the visible part of the horizontal scan line
(this allows,
roughly, for borders and sweepback time -- that is, the time
required for the
beam to move from the right screen edge to the left edge of the next
raster
line). In this example, that's 944 ticks.
Now, to get the normal 4:3 screen aspect ratio, set your vertical
resolution
to 3/4ths of the horizontal resolution you just calculated. For
this exam-
ple, that's 708 ticks. To get your actual VFL, multiply that by
1.05 to get
743 ticks.
The 4:3 is not technically magic; nothing prevents you from using a
non-
Golden-Section ratio if that will get the best use out of your
screen real
estate. It does make figuring frame height and frame width from the
diagonal
size convenient, you just multiply the diagonal by by 0.8 to get
width and
0.6 to get height.
So, HFL=1176 and VFL=743. Dividing 65MHz by the product of the two
gives us
a nice, healthy 74.4Hz refresh rate. Excellent! Better than VESA
standard!
And you got 944x708 to boot, more than the 800 by 600 you were
probably
expecting. Not bad at all!
You can even improve the refresh rate further, to almost 76 Hz, by
using the
fact that monitors can often sync horizontally at 2khz or so higher
than
rated, and by lowering VFL somewhat (that is, taking less than 75%
of 944 in
the example above). But before you try this "overdriving" maneuver,
if you
do, make sure that your monitor electron guns can sync up to 76 Hz
vertical.
(the popular NEC 4D, for instance, cannot. It goes only up to 75 Hz
VSF).
(See Overdriving Your Monitor (section 11., page 1) for more general
discus-
sion of this issue. )
So far, most of this is simple arithmetic and basic facts about
raster dis-
plays. Hardly any black magic at all!
9. Black Magic and Sync Pulses
OK, now you've computed HFL/VFL numbers for your chosen dot clock,
found the
refresh rate acceptable, and checked that you have enough VRAM. Now
for the
real black magic -- you need to know when and where to place
synchronization
pulses.
The sync pulses actually control the horizontal and vertical scan
frequebcies
of the monitor. The HSF and VSF you've pulled off the spec sheet
are nomi-
nal, approximate maximum sync frequencies. The sync pulse in the
signal from
the adapter card tells the monitor how fast to actually run.
Recall the two pictures above? Only part of the time required for
raster-
scanning a frame is used for displaying viewable image (ie. your
resolution).
9.1 Horizontal Sync:
By previous definition, it takes HFL ticks to trace the a horizontal
scan
line. Let's call the visible tick count (your horizontal screen
resolution)
HR. Then Obviously, HR < HFL by definition. For concreteness,
let's assume
both start at the same instant as shown below:
|___ __ __ __ __ __ __ __ __ __ __ __ __
|_ _ _ _ _ _ _ _ _ _ _ _ |
|_______________________|_______________|_____
0 ^ ^ unit: ticks
| ^ ^ |
HR | | HFL
| |<----->| |
|<->| HSP |<->|
HGT1 HGT2
Now, we would like to place a sync pulse of length HSP as shown
above, ie,
between the end of clock ticks for display data and the end of clock
ticks
for the entire frame. Why so? because if we can achieve this, then
your
screen image won't shift to the right or to the left. It will be
where it
supposed to be on the screen, covering squarely the monitor's
viewable area.
Furthermore, we want about 30 ticks of "guard time" on either side
of the
sync pulse. This is represented by HGT1 and HGT2. In a typical
configura-
tion HGT1 != HGT2, but if you're building a configuration from
scratch, you
want to start your experimentation with them equal (that is, with
the sync
pulse centered).
The symptom of a misplaced sync pulse is that the image is displaced
on the
screen, with one border excessively wide and the other side of the
image
wrapped around the screen edge, producing a white edge line and a
band of
"ghost image" on that side. A way-out-of-place vertical sync pulse
can actu-
ally cause the image to roll like a TV with a mis-adjusted vertical
hold (in
fact, it's the same phenomenon at work).
If you're lucky, your monitor's sync pulse widths will be documented
on its
specification page. If not, here's where the real black magic
starts...
You'll have to do a little trial and error for this part. But most
of the
time, we can safely assume that a sync pulse is about 3.5 to 4.0
microsecond
in length.
For concretness again, let's take HSP to be 3.8 microseconds (which
btw, is
not a bad value to start with when experimenting).
Now, using the 65Mhz clock timing above, we know HSP is equivalent
to 247
clock ticks (= 65 * 10**6 * 3.8 * 10^-6) [recall M=10^6,
micro=10^-6]
Some makers like to quote their horizontal framing parameters as
timings
rather than dot widths. You may see the following terms:
active time (HAT)
Corresponds to HR, but in milliseconds. HAT * DCF = HR.
blanking time (HBT)
Corresponds to (HFL - HR), but in milliseconds. HBT *
DCF = (HFL
- HR).
front porch (HFP)
This is just HGT1.
sync time
This is just HSP.
back porch (HBP)
This is just HGT2.
9.2 Vertical Sync:
Going back to the picture above, how do we place the 247 clock ticks
as shown
in the picture?
Using our example, HR is 944 and HFL is 1176. The difference
between the two
is 1176 - 944=232 < 247! Obviously we have to do some adjustment
here. What
can we do?
The first thing is to raise 1176 to 1184, and lower 944 to 936. Now
the dif-
ference = 1184-936= 248. Hmm, closer.
Next, instead using 3.8, we use 3.5 for calculating HSP; then, we
have
65*3.5=227. Looks better. But 248 is not much higher than 227.
It's nor-
mally necessary to have 30 or so clock ticks between HR and the
start of SP,
and the same for the end of SP and HFL. AND they have to be
multiple of
eight! Are we stuck?
No. Let's do this, 936 % 8 = 0, (936 + 32) % 8 = 0 too. But 936 +
32 = 968,
968 + 227 = 1195, 1195 + 32 = 1227. Hmm.. this looks not too bad.
But it's
not a multiple of 8, so let's round it up to 1232.
But now we have potential trouble, the sync pulse is no longer
placed right
in the middle between h and H any more. Happily, using our
calculator we
find 1232 - 32 = 1200 is also a multiple of 8 and (1232 - 32) - 968
= 232
corresponding using a sync pulse of 3.57 micro second long, still
reasonable.
In addition, 936/1232 ~ 0.76 or 76%, still not far from 80%, so it
should be
all right.
Furthermore, using the current horizontal frame length, we basically
ask our
monitor to sync at 52.7khz (= 65Mhz/1232) which is within its
capability. No
problems.
Using rules of thumb we mentioned before, 936*75%=702, This is our
new verti-
cal resolution. 702 * 1.05 = 737, our new vertical frame length.
Screen refresh rate = 65Mhz/(737*1232)=71.6 Hz. This is still
excellent.
Figuring the vertical sync pulse layout is similar:
|___ __ __ __ __ __ __ __ __ __ __ __ __
|_ _ _ _ _ _ _ _ _ _ _ _ |
|_______________________|_______________|_____
0 VR VFL unit: ticks
^ ^ ^
| | |
|<->|<----->|
VGT VSP
We start the sync pulse just past the end of the vertical display
data ticks.
VGT is the vertical guard time required for the sync pulse. Most
monitors
are comfortable with a VGT of 0 (no guard time) and we'll use that
in this
example. A few need two or three ticks of guard time, and it
usually doesn't
hurt to add that.
Returning to the example: since by the defintion of frame length, a
vertical
tick is the time for tracing a complete HORIZONTAL frame, therefore
in our
example, it is 1232/65Mhz=18.95us.
Experience shows that a vertical sync pulse should be in the range
of 50us
and 300us. As an example let's use 150us, which translates into 8
vertical
clock ticks (150us/18.95us~8).
Some makers like to quote their vertical framing parameters as
timings rather
than dot widths. You may see the following terms:
active time (VAT)
Corresponds to VR, but in milliseconds. VAT * VSF = VR.
blanking time (VBT)
Corresponds to (VFL - VR), but in milliseconds. VBT *
VSF = (VFL
- VR).
front porch (VFP)
This is just VGT.
sync time
This is just VSP.
back porch (VBP)
This is like a second guard time after the vertical sync
pulse.
It is often zero.
10. Putting it All Together
The Xconfig file Table of Video Modes contains lines of numbers,
with each
line being a complete specification for one mode of X-server
operation. The
fields are grouped into four sections, the name section, the clock
frequency
section, the horizontal section, and the vertical section.
The name section contains one field, the name of the video mode
specified by
the rest of the line. This name is referred to on the "Modes" line
of the
Graphics Driver Setup section of the Xconfig file. The name field
may be
omitted if the name of a previous line is the same as the current
line.
The dot clock section contains only the dot clock (what we've called
DCF)
field of the video mode line. The number in this field specifies
what dot
clock was used to generate the numbers in the following sections.
The horizontal section consists of four fields which specify how
each hori-
zontal line on the display is to be generated. The first field of
the sec-
tion contains the number of dots per line which will be illuminated
to form
the picture (what we've called HR). The second field of the section
indi-
cates at which dot the horizontal sync pulse will begin. The third
field
indicates at which dot the horizontal sync pulse will end. The
fourth field
specifies the toal horzontal frame length (HFL).
The vertical section also contains four fields. The first field
contains the
number of visible lines which will appear on the display (VR). The
second
field indicates the line number at which the vertical sync pulse
will begin.
The third field specifies the line number at which the vertical sync
pulse
will end. The fourth field contains the total vertical frame length
(VFL).
Example:
#Modename clock horizontal timing vertical timing
"752x564" 40 752 784 944 1088 564 567 569 611
44.5 752 792 976 1240 564 567 570 600
(Note: stock X11R5 doesn't support fractional dot clocks.)
For Xconfig, all of the numbers just mentioned - the number of
illuminated
dots on the line, the number of dots separating the illuminated dots
from the
beginning of the sync pulse, the number of dots representing the
duration of
the pulse, and the number of dots after the end of the sync pulse -
are added
to produce the number of dots per line. The number of horizontal
dots must
be evenly divisible by eight.
Example horizontal numbers: 800 864 1024 1088
This sample line has the number of illuminated dots (800) followed
by the
number of the dot when the sync pulse starts (864), followed by the
number of
the dot when the sync pulse ends (1024), followed by the number of
the last
dot on the horizontal line (1088).
Note again that all of the horizontal numbers (800, 864, 1024, and
1088) are
divisible by eight! This is not required of the vertical numbers.
The number of lines from the top of the display to the bottom form
the frame.
The basic timing signal for a frame is the line. A number of lines
will con-
tain the picture. After the last illuminated line has been
displayed, a
delay of a number of lines will occur before the vertical sync pulse
is gen-
erated. Then the sync pulse will last for a few lines, and finally
the last
lines in the frame, the delay required after the pulse, will be
generated.
The numbers that specify this mode of operation are entered in a
manner simi-
lar to the following example.
Example vertical numbers: 600 603 609 630
This example indicates that there are 600 visible lines on the
display, that
the vertical sync pulse starts with the 603rd line and ends with the
609th,
and that there are 630 total lines being used.
Note that the vertical numbers don't have to be divisible by eight!
Let's return to the example we've been working. According to the
above, all
we need to do from now on is to write our result into Xconfig as
follows:
<name> DCF HR SH1 SH2 HFL VR SV1 SV2 VFL
where SH1 is the start tick of the horizontal sync pulse and SH2 is
its end
tick; similarly, SV1 is the start tick of the vertical sync pulse
and SV2 is
its end tick.
#name clock horizontal timing vertical timing flag
936x702 65 936 968 1200 1232 702 702 710 737
No special flag necessary; this is a non-interlaced mode. Now we
are really
done.
11. Overdriving Your Monitor
You should absolutely not try exceeding your monitor's scan rates if
it's a
fixed-frequency type. You can smoke your hardware doing this!
There are
potentially subtler problems with overdriving a multisync monitor
which you
should be aware of.
Having a pixel clock higher than the monitor's maximum bandwidth is
rather
harmless, in contrast. (Note: the theoretical limit of discernable
features
is reached when the pixel clock reaches double the monitor's
bandwidth. This
is a straightforward application of Nyquist's Theorem: consider the
pixels as
a spatially distributed series of samples of the drive signals and
you'll see
why.)
It's exceeding the rated maximum sync frequencies that's
problematic. Some
modern monitors might have protection circuitry that shuts the
monitor down
at dangerous scan rates, but don't rely on it. In particular there
are older
multisync monitors (like the Multisync II) which use just one
horizontal
transformer. These monitors will not have much protection against
overdriving
them. While you necessarily have high voltage regulation circuitry
(which
can be absent in fixed frequency monitors), it will not necessarily
cover
every conceivable frequency range, especially in cheaper models.
This not
only implies more wear on the circuitry, it can also cause the
screen phos-
phors to age faster, and cause more than the specified radiation
(including
X-rays) to be emitted from the monitor.
Another importance of the bandwidth is that the monitor's input
impedance is
specified only for that range, and using higher frequencies can
cause reflec-
tions probably causing minor screen interferences, and radio
disturbance.
However, the basic problematic magnitude in question here is the
slew rate
(the steepness of the video signals) of the video output drivers,
and that is
usually independent of the actual pixel frequency, but (if your
board manu-
facturer cares about such problems) related to the maximum pixel
frequency of
the board.
So be careful out there...
12. Using Interlaced Modes
(This section is largely due to David Kastrup
<dak@pool.informatik.rwth-
aachen.de>)
At a fixed dot clock, an interlaced display is going to have
considerably
less noticable flicker than a non-interlaced display, if the
vertical cir-
cuitry of your monitor is able to support it stably. It is because
of this
that interlaced modes were invented in the first place.
Interlaced modes got their bad repute because they are inferior to
their non-
interlaced companions at the same vertical scan frequency, VSF
(which is what
is usually given in advertisements). But they are definitely
superior at the
same horizontal scan rate, and that's where the decisive limits of
your moni-
tor/graphics card usually lie.
At a fixed refresh rate (or half frame rate, or VSF) the interlaced
display
will flicker more: a 90Hz interlaced display will be inferior to a
90Hz non-
interlaced display. It will, however, need only half the video
bandwidth and
half the horizontal scan rate. If you compared it to a
non-interlaced mode
with the same dot clock and the same scan rates, it would be vastly
superior:
45Hz non-interlaced is intolerable. With 90Hz interlaced, I have
worked for
years with my Multisync 3D (at 1024x768) and am very satisfied. I'd
guess
you'd need at least a 70Hz non-interlaced display for similar
comfort.
You have to watch a few points, though: use interlaced modes only at
high
resolutions, so that the alternately lighted lines are close
together. You
might want to play with sync pulse widths and positions to get the
most sta-
ble line positions. If alternating lines are bright and dark,
interlace will
jump at you. I have one application that chooses such a dot pattern
for a
menu background (XCept, no other application I know does that,
fortunately).
I switch to 800x600 for using XCept because it really hurts my eyes
other-
wise.
For the same reason, use at least 100dpi fonts, or other fonts where
horizon-
tal beams are at least two lines thick (for high resolutions,
nothing else
will make sense anyhow).
And of course, never use an interlaced mode when your hardware would
support
a non-interlaced one with similar refresh rate.
If, however, you find that for some resolution you are pushing
either monitor
or graphics card to their upper limits, and getting
dissatisfactorily flick-
ery or outwashed (bandwidth exceeded) display, you might want to try
tackling
the same resolution using an interlaced mode. Of course this is
useless if
the VSF of your monitor is already close to its limits.
Design of interlaced modes is easy: do it like a non-interlaced
mode. Just
two more considerations are necessary: you need an odd total number
of verti-
cal lines (the last number in your mode line), and when you specify
the
"interlace" flag, the actual vertical frame rate for your monitor
doubles.
Your monitor needs to support a 90Hz frame rate if the mode you
specified
looks like a 45Hz mode apart from the "Interlace" flag.
As an example, here is my modeline for 1024x768 interlaced: my
Multisync 3D
will support up to 90Hz vertical and 38kHz horizontal.
ModeLine "1024x768" 45 1024 1048 1208 1248 768 768 776 807
Interlace
Both limits are pretty much exhausted with this mode. Specifying the
same
mode, just without the "Interlace" flag, still is almost at the
limit of the
monitor's horizontal capacity (and strictly speaking, a bit under
the lower
limit of vertical scan rate), but produces an intolerably flickery
display.
Basic design rules: if you have designed a mode at less than half of
your
monitor's vertical capacity, make the vertical total of lines odd
and add the
"Interlace" flag. The display's quality should vastly improve in
most cases.
If you have a non-interlaced mode otherwise exhausting your
monitor's specs
where the vertical scan rate lies about 30% or more under the
maximum of your
monitor, hand-designing an interlaced mode (probably with somewhat
higher
resolution) could deliver superior results, but I won't promise it.
13. Questions and Answers
Q. The example you gave is not a standard screen size, can I use it?
A. Why not? There is NO reason whatsover why you have to use
640x480,
800x600, or even 1024x768. The XFree86 servers let you configure
your hard-
ware with a lot of freedom. It usually takes two to three tries to
come up
the right one. The important thing to shoot for is high refresh
rate with
reasonable viewing area. not high resolution at the price of
eye-tearing
flicker!
Q. It this the only resolution given the 65Mhz dot clock and 55Khz
HSF?
A. Absolutely not! You are encouraged to follow the general
procedure and do
some trial-and-error to come up a setting that's really to your
liking.
Experimenting with this can be lots of fun. Most settings may just
give you
nasty video hash, but in practice a modern multi-sync monitor is
usually not
damaged easily. Be sure though, that your monitor can support the
frame rates
of your mode before using it for longer times.
Beware fixed-frequency monitors! This kind of hacking around can
damage them
rather quickly. Be sure you use valid refresh rates for every
experiment on
them.
Q. You just mentioned two standard resolutions. In Xconfig, there
are many
standard resolutions available, can you tell me whether there's any
point in
tinkering with timings?
A. Absolutely! Take, for example, the "standard" 640x480 listed in
the cur-
rent Xconfig. It employes 25Mhz driving frequency, frame lengths
are 800 and
525 => refresh rate ~ 59.5Hz. Not too bad. But 28Mhz is a commonly
available
driving frequency from many SVGA boards. If we use it to drive
640x480, fol-
lowing the procedure we discussed above, you would get frame lengths
like 812
and 505. Now the refresh rate is raised to 68Hz, a quite
significant
improvement over the standard one.
Q. Can you summarize what we have discussed so far?
A. In a nutshell:
1. for any fixed driving frequency, raising max resolution incurs
the
penalty of lowering refresh rate and thus introducing more
flicker.
2. if high resolution is desirable and your monitor supports it,
try to
get a SVGA card that provides a matching dot clock or DCF. The
higher,
the better!
14. Fixing Problems with the Image.
OK, so you've got your X configuration numbers. You put them in
Xconfig with
a test mode label. You fire up X, hot-key to the new mode, ... and
the image
doesn't look right. What do you do? Here's a list of common
problems and
how to fix them.
(Fixing these minor distortions is where xvidtune(1) really shines.)
You move the image by changing the sync pulse timing. You scale it
by chang-
ing the frame length (you need to move the sync pulse to keep it in
the same
relative position, otherwise scaling will move the image as well).
Here are
some more specific recipes:
The horizontal and vertical positions are independent. That is,
moving the
image horizontally doesn't affect placement vertically, or
vice-versa. How-
ever, the same is not quite true of scaling. While changing the
horizontal
size does nothing to the vertical size or vice versa, the total
change in
both may be limited. In particular, if your image is too large in
both
dimensions you will probably have to go to a higher dot clock to fix
it.
Since this raises the usable resolution, it is seldom a problem!
14.1 The image is displaced to the left or right
To fix this, move the horizontal sync pulse. That is, increment or
decrement
(by a multiple of 8) the middle two numbers of the horizontal timing
section
that define the leading and trailing edge of the horizontal sync
pulse.
If the image is shifted left (right border too large, you want to
move the
image to the right) decrement the numbers. If the image is shifted
right
(left border too large, you want it to move left) increment the sync
pulse.
14.2 The image is displaced up or down
To fix this, move the vertical sync pulse. That is, increment or
decrement
the middle two numbers of the vertical timing section that define
the leading
and trailing edge of the vertical sync pulse.
If the image is shifted up (lower border too large, you want to move
the
image down) decrement the numbers. If the image is shifted down
(top border
too large, you want it to move up) increment the numbers.
14.3 The image is too large both horizontally and vertically
Switch to a higher card clock speed. If you have multiple modes in
your clock
file, possibly a lower-speed one is being activated by mistake.
14.4 The image is too wide (too narrow) horizontally
To fix this, increase (decrease) the horizontal frame length. That
is,
change the fourth number in the first timing section. To avoid
moving the
image, also move the sync pulse (second and third numbers) half as
far, to
keep it in the same relative position.
14.5 The image is too deep (too shallow) vertically
To fix this, increase (decrease) the vertical frame length. That
is, change
the fourth number in the second timing section. To avoid moving the
image,
also move the sync pulse (second and third numbers) half as far, to
keep it
in the same relative position.
Any distortion that can't be handled by combining these techniques
is proba-
bly evidence of something more basically wrong, like a calculation
mistake or
a faster dot clock than the monitor can handle.
Finally, remember that increasing either frame length will decrease
your
refresh rate, and vice-versa.
15. Plotting Monitor Capabilities
To plot a monitor mode diagram, you'll need the gnuplot package (a
freeware
plotting language for UNIX-like operating systems) and the tool
modeplot, a
shell/gnuplot script to plot the diagram from your monitor
characteristics,
entered as command-line options.
Here is a copy of modeplot:
#!/bin/sh
#
# modeplot -- generate X mode plot of available monitor modes
#
# Do `modeplot -?' to see the control options.
#
# ($Id: video-modes.sgml,v 1.2 1997/08/08 15:07:24 esr Exp $)
# Monitor description. Bandwidth in MHz, horizontal frequencies
in kHz
# and vertical frequencies in Hz.
TITLE="Viewsonic 21PS"
BANDWIDTH=185
MINHSF=31
MAXHSF=85
MINVSF=50
MAXVSF=160
ASPECT="4/3"
vesa=72.5 # VESA-recommended minimum refresh rate
while [ "$1" != "" ]
do
case $1 in
-t) TITLE="$2"; shift;;
-b) BANDWIDTH="$2"; shift;;
-h) MINHSF="$2" MAXHSF="$3"; shift; shift;;
-v) MINVSF="$2" MAXVSF="$3"; shift; shift;;
-a) ASPECT="$2"; shift;;
-g) GNUOPTS="$2"; shift;;
-?) cat <<EOF
modeplot control switches:
-t "<description>" name of monitor defaults to
"Viewsonic 21PS"
-b <nn> bandwidth in MHz defaults to 185
-h <min> <max> min & max HSF (kHz) defaults to 31
85
-v <min> <max> min & max VSF (Hz) defaults to 50
160
-a <aspect ratio> aspect ratio defaults to 4/3
-g "<options>" pass options to gnuplot
The -b, -h and -v options are required, -a, -t, -g optional.
You can
use -g to pass a device type to gnuplot so that (for example)
modeplot's
output can be redirected to a printer. See gnuplot(1) for
details.
The modeplot tool was created by Eric S. Raymond
<esr@thyrsus.com> based on
analysis and scratch code by Martin Lottermoser
<Martin.Lottermoser@mch.sni.de>
This is modeplot $Revision: 1.2 $
EOF
exit;;
esac
shift
done
gnuplot $GNUOPTS <<EOF
set title "$TITLE Mode Plot"
# Magic numbers. Unfortunately, the plot is quite sensitive to
changes in
# these, and they may fail to represent reality on some
monitors. We need
# to fix values to get even an approximation of the mode
diagram. These come
# from looking at lots of values in the ModeDB database.
F1 = 1.30 # multiplier to convert horizontal resolution to
frame width
F2 = 1.05 # multiplier to convert vertical resolution to frame
height
# Function definitions (multiplication by 1.0 forces
real-number arithmetic)
ac = (1.0*$ASPECT)*F1/F2
refresh(hsync, dcf) = ac * (hsync**2)/(1.0*dcf)
dotclock(hsync, rr) = ac * (hsync**2)/(1.0*rr)
resolution(hv, dcf) = dcf * (10**6)/(hv * F1 * F2)
# Put labels on the axes
set xlabel 'DCF (MHz)'
set ylabel 'RR (Hz)' 6 # Put it right over the Y axis
# Generate diagram
set grid
set label "VB" at $BANDWIDTH+1, ($MAXVSF + $MINVSF) / 2 left
set arrow from $BANDWIDTH, $MINVSF to $BANDWIDTH, $MAXVSF
nohead
set label "max VSF" at 1, $MAXVSF-1.5
set arrow from 0, $MAXVSF to $BANDWIDTH, $MAXVSF nohead
set label "min VSF" at 1, $MINVSF-1.5
set arrow from 0, $MINVSF to $BANDWIDTH, $MINVSF nohead
set label "min HSF" at dotclock($MINHSF, $MAXVSF+17), $MAXVSF +
17 right
set label "max HSF" at dotclock($MAXHSF, $MAXVSF+17), $MAXVSF +
17 right
set label "VESA $vesa" at 1, $vesa-1.5
set arrow from 0, $vesa to $BANDWIDTH, $vesa nohead # style -1
plot [dcf=0:1.1*$BANDWIDTH] [$MINVSF-10:$MAXVSF+20] \
refresh($MINHSF, dcf) notitle with lines 1, \
refresh($MAXHSF, dcf) notitle with lines 1, \
resolution(640*480, dcf) title "640x480 " with points 2, \
resolution(800*600, dcf) title "800x600 " with points 3, \
resolution(1024*768, dcf) title "1024x768 " with points 4, \
resolution(1280*1024, dcf) title "1280x1024" with points 5, \
resolution(1600*1280, dcf) title "1600x1200" with points 6
pause 9999
EOF
Once you know you have modeplot and the gnuplot package in place,
you'll need
the following monitor characteristics:
o video bandwidth (VB)
o range of horizontal sync frequency (HSF)
o range of vertical sync frequency (VSF)
The plot program needs to make some simplifying assumptions which
are not
necessarily correct. This is the reason why the resulting diagram
is only a
rough description. These assumptions are:
1. All resolutions have a single fixed aspect ratio AR = HR/VR.
Standard
resolutions have AR = 4/3 or AR = 5/4. The modeplot programs
assumes
4/3 by default, but you can override this.
2. For the modes considered, horizontal and vertical frame
lengths are
fixed multiples of horizontal and vertical resolutions,
respectively:
HFL = F1 * HR
VFL = F2 * VR
As a rough guide, take F1 = 1.30 and F2 = 1.05 (see frame (section
8., page
1) "Computing Frame Sizes").
Now take a particular sync frequency, HSF. Given the assumptions
just pre-
sented, every value for the clock rate DCF already determines the
refresh
rate RR, i.e. for every value of HSF there is a function RR(DCF).
This can
be derived as follows.
The refresh rate is equal to the clock rate divided by the product
of the
frame sizes:
RR = DCF / (HFL * VFL) (*)
On the other hand, the horizontal frame length is equal to the clock
rate
divided by the horizontal sync frequency:
HFL = DCF / HSF (**)
VFL can be reduced to HFL be means of the two assumptions above:
VFL = F2 * VR
= F2 * (HR / AR)
= (F2/F1) * HFL / AR (***)
Inserting (**) and (***) into (*) we obtain:
RR = DCF / ((F2/F1) * HFL**2 / AR)
= (F1/F2) * AR * DCF * (HSF/DCF)**2
= (F1/F2) * AR * HSF**2 / DCF
For fixed HSF, F1, F2 and AR, this is a hyperbola in our diagram.
Drawing
two such curves for minimum and maximum horizontal sync frequencies
we have
obtained the two remaining boundaries of the permitted region.
The straight lines crossing the capability region represent
particular reso-
lutions. This is based on (*) and the second assumption:
RR = DCF / (HFL * VFL) = DCF / (F1 * HR * F2 * VR)
By drawing such lines for all resolutions one is interested in, one
can imme-
diately read off the possible relations between resolution, clock
rate and
refresh rate of which the monitor is capable. Note that these lines
do not
depend on monitor properties, but they do depend on the second
assumption.
The modeplot tool provides you with an easy way to do this. Do
modeplot -?
to see its control options. A typical invocation looks like this:
modeplot -t "Swan SW617" -b 85 -v 50 90 -h 31 58
The -b option specifies video bandwidth; -v and -h set horizontal
and verti-
cal sync frequency ranges.
When reading the output of modeplot, always bear in mind that it
gives only
an approximate description. For example, it disregards limitations
on HFL
resulting from a minimum required sync pulse width, and it can only
be accu-
rate as far as the assumptions are. It is therefore no substitute
for a
detailed calculation (involving some black magic) as presented in
Putting it
All Together (section 10., page 1). However, it should give you a
better
feeling for what is possible and which tradeoffs are involved.
16. Credits
The original ancestor of this document was by Chin Fang
<fangchin@leland.stanford.edu>.
Eric S. Raymond <esr@snark.thyrsus.com> reworked, reorganized, and
massively
rewrote Chin Fang's original in an attempt to understand it. In the
process,
he merged in most of a different how-to by Bob Crosson
<crosson@cam.nist.gov>.
The material on interlaced modes is largely by David Kastrup
<dak@pool.infor-
matik.rwth-aachen.de>
Martin Lottermoser <Martin.Lottermoser@mch.sni.de> contributed the
idea of
using gnuplot to make mode diagrams and did the mathematical
analysis behind
modeplot. The distributed modeplot was redesigned and generalized
by ESR
from Martin's original gnuplot code for one case.
Generated from XFree86:
xc/programs/Xserver/hw/xfree86/doc/sgml/VidModes.sgml,v 3.14
1997/11/16 10:52:47 dawes Exp $
$XConsortium: VidModes.sgml /main/7 1996/02/21 17:46:17 kaleb $
$XFree86: xc/programs/Xserver/hw/xfree86/doc/VideoModes.doc,v 3.18
1999/04/15 03:35:09 dawes Exp $
> -----Original Message-----
> From: cygwin-xfree-owner@sourceware.cygnus.com
> [ mailto:cygwin-xfree-owner@sourceware.cygnus.com]On Behalf Of Mike
> MacDonald
> Sent: Friday, November 12, 1999 11:32 AM
> To: 'cygwin-xfree@sourceware.cygnus.com'
> Subject: FW: XF86SUP.SYS
>
>
>
>
> -----Original Message-----
> From: Mike MacDonald
> Sent: Friday, November 12, 1999 11:30 AM
> To: 'Holger Veit'
> Subject: XF86SUP.SYS
>
>
> Hello again. I have some other questions. How does X
> change video modes?
> I see where you get the vidmem, but not where the
> graphics mode is actually
> set on the card. I can use directx to get a pointer to
> memory, but I would
> have to use directx to set the video mode I think.
>
> I have a sinking feeling that X is setting the video mode
> through the io
> ports on the card, which meens I prolly can't use direct
> x, and need to
> switch to fullscreen mode if I can, and map the memory over.
>
> Unfortunately that makes it more difficult to display X
> in a window which
> would be nice. Unless I just pick the svga server, and
> fix that to use
> DirectX.. Or go nuts and make a directx server which
> would prolly be the
> best way to go.. I don't know, I think for now I'll
> either pick a mode and
> just support 1 mode, or try and go to a fullscreen mode
> and map the memory..
> If you can let me know how X changes video modes, it
> would be really
> helpful, thanx!
>
-------------- next part --------------
XFree86 X server ``New Design'' (DRAFT)
The XFree86 Project, Inc
Last modified 17 July 1999
NOTE: This is a DRAFT document, and the interfaces described here are subject
to change without notice.
1. Preface
The broad design principles are:
o keep it reasonable
o We cannot rewrite the complete server
o We don't want to re-invent the wheel
o keep it modular
o As many things as possible should go into modules
o The basic loader binary should be minimal
o A clean design with well defined layering is important
o DDX specific global variables are a nono
o The structure should be flexible enough to allow future extensions
o The structure should minimize duplication of common code
o keep important features in mind
o multiple screens, including multiple instances of drivers
o mixing different color depths and visuals on different and ideally
even on the same screen
o better control of the PCI device used
o better config file parser
o get rid of all VGA compatibility assumptions
Unless we find major deficiencies in the DIX layer, we should avoid making
changes there.
2. The XF86Config File
The XF86Config file format is similar to the old format, with the following
changes:
2.1 Device section
The Device sections are similar to what they used to be, and describe hard-
ware-specific information for a single video card. Device Some new keywords
are added:
Driver "drivername"
Specifies the name of the driver to be used for the card. This
is mandatory.
BusID "busslot"
Specifies uniquely the location of the card on the bus. The pur-
pose is to identify particular cards in a multi-headed configura-
tion. The format of the argument is intentionally vague, and may
be architecture dependent. For a PCI bus, it is something like
"bus:slot:func".
A Device section is considered ``active'' if there is a reference to it in an
active Screen section.
2.2 Screen section
The Screen sections are similar to what they used to be. They no longer have
a Driver keyword, but an Identifier keyword is added. (The Driver keyword
may be accepted in place of the Identifier keyword for compatibility pur-
poses.) The identifier can be used to identify which screen is to be active
when multiple Screen sections are present. It is possible to specify the
active screen from the command line. A default is chosen in the absence of
one being specified. A Screen section is considered ``active'' if there is a
reference to it either from the command line, or from an active ServerLayout
section.
2.3 InputDevice section
The InputDevice section is a new section that describes configuration infor-
mation for input devices. It replaces the old Keyboard, Pointer and XInput
sections. Like the Device section, it has two mandatory keywords: Identifier
and Driver. For compatibility purposes the old Keyboard and Pointer sections
are converted by the parser into InputDevice sections as follows:
Keyboard
Identifier "Implicit Core Keyboard"
Driver "keyboard"
Pointer
Identifier "Implicit Core Pointer"
Driver "mouse"
An InputDevice section is considered active if there is a reference to it in
an active ServerLayout section. An InputDevice section may also be refer-
enced implicitly if there is no ServerLayout section, if the -screen command
line options is used, or if the ServerLayout section doesn't reference any
InputDevice sections. In this case, the first sections with drivers "key-
board" and "mouse" are used as the core keyboard and pointer respectively.
2.4 ServerLayout section
The ServerLayout section is a new section that is used to identify which
Screen sections are to be used in a multi-headed configuration, and the rela-
tive layout of those screens. It also identifies which InputDevice sections
are to be used. Each ServerLayout section has an identifier, a list of
Screen section identifiers, and a list of InputDevice section identifiers.
ServerFlags options may also be included in a ServerLayout section, making it
possible to override the global values in the ServerFlags section.
A ServerLayout section can be made active by being referenced on the command
line. In the absence of this, a default will be chosen (the first one
found). The screen names may optionally be followed by a number specifying
the preferred screen number, and optionally by the names of the four screens
adjacent to it. The order of these is top, bottom, left, right. When no
screen number is specified, they are numbered according to the order in which
they are listed. Here is an example of a ServerLayout section for two
screens, with the second located to the right of the first:
Section "ServerLayout"
Identifier "Main Layout"
Screen "Screen 1" 0 "" "" "" "Screen 2"
Screen "Screen 2" 1
Screen "Screen 3"
EndSection
2.5 Options
Options are used more extensively. They may appear in most sections now.
Options related to drivers can be present in the Screen, Device and Monitor
sections and the Display subsections. The order of precedence is Display,
Screen, Monitor, Device. Options have been extended to allow an optional
value to be specified in addition to the option name. For more details about
options, see the Options (section 10., page 1) section for details.
3. Driver Interface
The driver interface consists of a minimal set of entry points that are
required based on the external events that the driver must react to. No non-
essential structure is imposed on the way they are used beyond that. This is
a significant difference compared with the old design.
The entry points for drawing operations are already taken care of by the
framebuffer code (including, XAA). Extensions and enhancements to frame-
buffer code are outside the scope of this document.
This approach to the driver interface provides good flexibility, but does
increase the complexity of drivers. To help address this, the XFree86 common
layer provides a set of ``helper'' functions to take care of things that most
drivers need. These helpers help minimise the amount of code duplication
between drivers. The use of helper functions by drivers is however optional,
though encouraged. The basic philosophy behind the helper functions is that
they should be useful to many drivers, that they should balance this against
the complexity of their interface. It is inevitable that some drivers may
find some helpers unsuitable and need to provide their own code.
Events that a driver needs to react to are:
ScreenInit
An initialisation function is called from the DIX layer for each
screen at the start of each server generation.
Enter VT
The server takes control of the console.
Leave VT
The server releases control of the console.
Mode Switch
Change video mode.
ViewPort change
Change the origin of the physical view port.
ScreenSaver state change
Screen saver activation/deactivation.
CloseScreen
A close screen function is called from the DIX layer for each
screen at the end of each server generation.
In addition to these events, the following functions are required by the
XFree86 common layer:
Identify
Print a driver identifying message.
Probe
This is how a driver identifies if there is any hardware present
that it knows how to drive.
PreInit
Process information from the XF86Config file, determine the full
characteristics of the hardware, and determine if a valid config-
uration is present.
The VidMode extension also requires:
ValidMode
Identify if a new mode is usable with the current configuration.
The PreInit function (and/or helpers it calls) may also make use
of the ValidMode function or something similar.
Other extensions may require other entry points. The drivers will inform the
common layer of these in such cases.
4. Resource Access Control Introduction
Graphics devices are accessed through ranges in I/O or memory space. While
most modern graphics devices allow relocation of such ranges many of them
still require the use of well established interfaces such as VGA memory and
IO ranges or 8514/A IO ranges. With modern buses (like PCI) it is possible
for multiple video devices to share access to these resources. The RAC
(Resource Access Control) subsystem provides a mechanism for this.
4.1 Terms and Definitions
4.1.1 Bus
``Bus'' is ambiguous as it is used for different things: it may refer to
physical incompatible extension connectors in a computer system. The RAC
system knows two such systems: The ISA bus and the PCI bus. (On the software
level EISA, MCA and VL buses are currently treated like ISA buses). ``Bus''
may also refer to logically different entities on a single bus system which
are connected via bridges. A PCI system may have several distinct PCI buses
connecting each other by PCI-PCI bridges or to the host CPU by HOST-PCI
bridges.
Systems that host more than one bus system link these together using bridges.
Bridges are a concern to RAC as they might block or pass specific resources.
PCI-PCI bridges may be set up to pass VGA resources to the secondary bus.
PCI-ISA buses pass any resources not decoded on the primary PCI bus to the
ISA bus. This way VGA resources (although exclusive on the ISA bus) can be
shared by ISA and PCI cards. Currently HOST-PCI bridges are not yet handled
by RAC as they require specific drivers.
4.1.2 Entity
The smallest independently addressable unit on a system bus is referred to as
an entity. So far we know ISA and PCI entities. PCI entities can be located
on the PCI bus by an unique ID consisting of the bus, card and function num-
ber.
4.1.3 Resource
``Resource'' refers to a range of memory or I/O addresses an entity can
decode.
If a device is capable of disabling this decoding the resource is called
sharable. For PCI devices a generic method is provided to control resource
decoding. Other devices will have to provide a device specific function to
control decoding.
If the entity is capable of decoding this range at a different location this
resource is considered relocatable.
Resources which start at a specific address and occupy a single continuous
range are called block resources.
Alternatively resource addresses can be decoded in a way that they satisfy
the conditions:
address & mask == base
and
base & mask == base
Resources addressed in such a way are called sparse resources.
4.1.4 Server States
The resource access control system knows two server states: the SETUP and the
OPERATING state. The SETUP state is entered whenever a mode change takes
place or the server exits or does VT switching. During this state all entity
resources are under resource access control. During OPERATING state only
those entities are controlled which actually have shared resources that con-
flict with others.
5. Control Flow in the Server and Mandatory Driver Functions
At the start of each server generation, main() (dix/main.c) calls the DDX
function InitOutput(). This is the first place that the DDX gets control.
InitOutput() is expected to fill in the global screenInfo struct, and one
screenInfo.screen[] entry for each screen present. Here is what InitOutput()
does:
5.1 Parse the XF86Config file
This is done at the start of the first server generation only.
The XF86Config file is read in full, and the resulting information stored in
data structures. None of the parsed information is processed at this point.
The parser data structures are opaque to the video drivers and to most of the
common layer code.
The entire file is parsed first to remove any section ordering requirements.
5.2 Initial processing of parsed information and command line options
This is done at the start of the first server generation only.
The initial processing is to determine paths like the ModulePath, etc, and to
determine which ServerLayout, Screen and Device sections are active.
5.3 Enable port I/O access
Port I/O access is controlled from the XFree86 common layer, and is ``all or
nothing''. It is enabled prior to calling driver probes, at the start of
subsequent server generations, and when VT switching back to the Xserver. It
is disabled at the end of server generations, and when VT switching away from
the Xserver.
The implementation details of this may vary on different platforms.
5.4 General bus probe
This is done at the start of the first server generation only.
In the case of ix86 machines, this will be a general PCI probe. The full
information obtained here will be available to the drivers. This information
persists for the life of the Xserver. In the PCI case, the PCI information
for all video cards found is available by calling xf86GetPciVideoInfo().
pciVideoPtr *xf86GetPciVideoInfo(void)
returns a pointer to a list of pointers to pciVideoRec
entries, of which there is one for each detected PCI
video card. The list is terminated with a NULL pointer.
If no PCI video cards were detected, the return value is
NULL.
After the bus probe, the resource broker is initialised.
5.5 Load initial set of modules
This is done at the start of the first server generation only.
The core server contains a list of mandatory modules. These are loaded
first. Currently the only module on this list is the bitmap font module.
The next set of modules loaded are those specified explicitly in the Module
section of the config file.
The final set of initial modules are the driver modules referenced by the
active Device and InputDevice sections in the config file. Each of these
modules is loaded exactly once.
5.6 Register Video and Input Drivers
This is done at the start of the first server generation only.
When a driver module is loaded, the loader calls its Setup function. For
video drivers, this function calls xf86AddDriver() to register the driver's
DriverRec, which contains a small set of essential details and driver entry
points required during the early phase of InitOutput(). xf86AddDriver() adds
it to the global xf86DriverList[] array.
The DriverRec contains the driver's version, a short descriptive message, the
Identify() and Probe() function entry points as well as a pointer to the
driver's module (as returned from the loader when the driver was loaded) and
a reference count which keeps track of how many screens are using the driver.
The entry driver entry points are those required prior to the driver allocat-
ing and filling in its ScrnInfoRec.
For a static server, the xf86DriverList[] array is initialised at build time,
and the loading of modules is not done.
A similar procedure is used for input drivers. The input driver's Setup
function calls xf86AddInputDriver() to register the driver's InputDriverRec,
which contains a small set of essential details and driver entry points
required during the early phase of InitInput(). xf86AddInputDriver() adds it
to the global xf86InputDriverList[] array. For a static server, the
xf86InputDriverList[] array is initialised at build time.
Both the xf86DriverList[] and xf86InputDriverList[] arrays have been ini-
tialised by the end of this stage.
Once all the drivers are registered, their ChipIdentify() functions are
called.
void ChipIdentify(int flags)
This is expected to print a message indicating the driver
name, a short summary of what it supports, and a list of
the chipset names that it supports. It may use the
xf86PrintChipsets() helper to do this.
void xf86PrintChipsets(const char *drvname, const char *drvmsg,
SymTabPtr chips)
This function provides an easy way for a driver's ChipI-
dentify function to format the identification message.
5.7 Initialise Access Control
This is done at the start of the first server generation only.
The Resource Access Control (RAC) subsystem is initialised before calling any
driver functions that may access hardware. All generic bus information is
probed and saved (for restoration later). All (shared resource) video
devices are disabled at the generic bus level, and a probe is done to find
the ``primary'' video device. These devices remain disabled for the next
step.
5.8 Video Driver Probe
This is done at the start of the first server generation only. The Chip-
Probe() function of each registered video driver is called.
Bool ChipProbe(DriverPtr drv, int flags)
The purpose of this is to identify all instances of hard-
ware supported by the driver. The flags value is cur-
rently not used, and should be ignored by the driver.
The probe must find the active device sections that match
the driver by calling xf86MatchDevice(). The number of
matches found limits the maximum number of instances for
this driver. If no matches are found, the problem should
return FALSE immediately.
Devices that cannot be identified by using device-inde-
pendent methods should be probed at this stage (keeping
in mind that access to all resources that can be disabled
in a device-independent way are disabled during this
phase). The probe must be a minimal probe. It should
just determine if there is a card present that the driver
can drive. It should use the least intrusive probe meth-
ods possible. It must not do anything that is not essen-
tial, like probing for other details such as the amount
of memory installed, etc. It is recommended that the
xf86MatchPciInstances() helper function be used for iden-
tifying matching PCI devices, and similarly the
xf86MatchIsaInstances() for ISA (non-PCI) devices (see
the RAC (section 9., page 1) section). These helpers
also checks and claims the appropriate entity. When not
using the helper, that should be done with xf86CheckPciS-
lot() and xf86ClaimPciSlot() for PCI devices and
xf86ClaimIsaSlot() for ISA devices (see the RAC (section
9., page 1) section).
The probe must register all non-relocatable resources at
this stage. If a resource conflict is found between
exclusive resources the driver will fail immediately.
This is usually best done with the xf86ConfigActivePciEn-
tity() helper function for PCI and xf86ConfigActiveIsaEn-
tity() for ISA (see the RAC (section 9., page 1) sec-
tion). It is possible to register some entity specific
functions with those helpers. When not using the
helpers, the xf86AddEntityToScreen() xf86ClaimFixe-
dResources() and xf86SetEntityFuncs() should be used
instead (see the RAC (section 9., page 1) section).
If a chipset is specified in an active device section
which the driver considers relevant (ie it has no driver
specified, or the driver specified matches the driver
doing the probe), the Probe must return FALSE if the
chipset doesn't match one supported by the driver.
If there are no active device sections that the driver
considers relevant, it must return FALSE.
Allocate a ScrnInfoRec for each instance of the hardware
found, and fill in the basic information, including the
other driver entry points. The xf86AllocateScreen()
function must be used to allocate the ScrnInfoRec, and it
takes care of initialising fields to defined ``unused''
values.
Claim the entities for each instance of the hardware
found. This prevents other drivers from claiming the
same hardware.
Must leave hardware in the same state it found it in, and
must not do any hardware initialisation.
All detection can be overridden via the config file, and
that parsed information is available to the driver at
this stage.
Returns TRUE if one or more instances are found, and
FALSE otherwise.
int xf86MatchDevice(const char *drivername,
GDevPtr **driversectlist)
This function takes the name of the driver and returns
via driversectlist a list of device sections that match
the driver name. The function return value is the number
of matches found. If a fatal error is encountered the
return value is -1.
The caller should use xfree() to free *driversectlist
when it is no longer needed.
ScrnInfoPtr xf86AllocateScreen(DriverPtr drv, int flags)
This function allocates a new ScrnInfoRec in the
xf86Screens[] array. This function is normally called by
the video driver ChipProbe() functions. The return value
is a pointer to the newly allocated ScrnInfoRec. The
scrnIndex, origIndex, module and drv fields are ini-
tialised. The reference count in drv is incremented.
The storage for any currently allocated ``privates''
pointers is also allocated and the privates field ini-
tialised (the privates data is of course not allocated or
initialised). This function never returns on failure.
If the allocation fails, the server exits with a fatal
error. The flags value is not currently used, and should
be set to zero.
At the completion of this, a list of ScrnInfoRecs have been allocated in the
xf86Screens[] array, and the associated entities and fixed resources have
been claimed. The following ScrnInfoRec fields must be initialised at this
point:
driverVersion
driverName
scrnIndex(*)
origIndex(*)
drv(*)
module(*)
name
Probe
PreInit
ScreenInit
EnterVT
LeaveVT
numEntities
entityList
access
(*) These are initialised when the ScrnInfoRec is allocated, and not explic-
itly by the driver.
The following ScrnInfoRec fields must be initialised if the driver is going
to use them:
SwitchMode
AdjustFrame
FreeScreen
ValidMode
5.9 Matching Screens
This is done at the start of the first server generation only.
After the Probe phase is finished, there will be some number of ScrnInfoRecs.
These are then matched with the active Screen sections in the XF86Config, and
those not having an active Screen section are deleted. If the number of
remaining screens is 0, InitOutput() sets screenInfo.numScreens to 0 and
returns.
At this point the following fields of the ScrnInfoRecs must be initialised:
confScreen
5.10 Allocate non-conflicting resources
This is done at the start of the first server generation only.
Before calling the drivers again, the resource information collected from the
Probe phase is processed. This includes checking the extent of PCI resources
for the probed devices, and resolving any conflicts in the relocatable PCI
resources. It also reports conflicts, checks bus routing issues, and any-
thing else that is needed to enable the entities for the next phase.
If any drivers registered an EntityInit() function during the Probe phase,
then they are called here.
5.11 Sort the Screens and pre-check Monitor Information
This is done at the start of the first server generation only.
The list of screens is sorted to match the ordering requested in the config
file.
The list of modes for each active monitor is checked against the monitor's
parameters. Invalid modes are pruned.
5.12 PreInit
This is done at the start of the first server generation only.
For each ScrnInfoRec, enable access to the screens entities and call the
ChipPreInit() function.
Bool ChipPreInit(ScrnInfoRec screen, int flags)
The purpose of this function is to find out all the
information required to determine if the configuration is
usable, and to initialise those parts of the ScrnInfoRec
that can be set once at the beginning of the first server
generation.
The number of entities registered for the screen should
be checked against the expected number (most drivers
expect only one). The entity information for each of
them should be retrieved (with xf86GetEntityInfo()) and
checked for the correct bus type and that none of the
sharable resources registered during the Probe phase was
rejected.
Access to resources for the entities that can be con-
trolled in a device-independent way are enabled before
this function is called. If the driver needs to access
any resources that it has disabled in an EntityInit()
function that it registered, then it may enable them here
providing that it disables them before this function
returns.
This includes probing for video memory, clocks, ramdac,
and all other HW info that is needed. It includes deter-
mining the depth/bpp/visual and related info. It
includes validating and determining the set of video
modes that will be used (and anything that is required to
determine that).
This information should be determined in the least intru-
sive way possible. The state of the HW must remain
unchanged by this function. Although video memory
(including MMIO) may be mapped within this function, it
must be unmapped before returning. Driver specific
information should be stored in a structure hooked into
the ScrnInfoRec's driverPrivate field. Any other modules
which require persistent data (ie data that persists
across server generations) should be initialised in this
function, and they should allocate a ``privates'' index
to hook their data into by calling xf86AllocateScrnInfo-
PrivateIndex(). The ``privates'' data is persistent.
Helper functions for some of these things are provided at
the XFree86 common level, and the driver can choose to
make use of them.
All additional resources that the screen needs must be
registered here. This should be done with xf86Register-
Resources(). If some of the fixed resources registered
in the Probe phase are not needed or not decoded by the
hardware when in the OPERATING server state, their status
should be updated with xf86SetOperatingState().
Modules may be loaded at any point in this function, and
all modules that the driver will need must be loaded
before the end of this function. The xf86LoadSubModule()
function should be used to load modules. A driver may
unload a module within this function if it was only
needed temporarily, and the UnloadSubModule() function
should be used to do that. Otherwise there is no need to
explicitly unload modules because the loader takes care
of module dependencies and will unload submodules auto-
matically if/when the driver module is unloaded.
The bulk of the ScrnInfoRec fields should be filled out
in this function.
ChipPreInit() returns FALSE when the configuration is
unusable in some way (unsupported depth, no valid modes,
not enough video memory, etc), and TRUE if it is usable.
It is expected that if the ChipPreInit() function returns
TRUE, then the only reasons that subsequent stages in the
driver might fail are lack or resources (like xalloc
failures). All other possible reasons for failure should
be determined by the ChipPreInit() function.
The ScrnInfoRecs for screens where the ChipPreInit() fails are removed. If
none remain, InitOutput() sets screenInfo.numScreens to 0 and returns.
At this point, further fields of the ScrnInfoRecs would normally be filled
in. Most are not strictly mandatory, but many are required by other layers
and/or helper functions that the driver may choose to use. The documentation
for those layers and helper functions indicates which they require.
The following fields of the ScrnInfoRecs should be filled in if the driver is
going to use them:
monitor
display
depth
pixmapBPP
bitsPerPixel
weight (>8bpp only)
mask (>8bpp only)
offset (>8bpp only)
rgbBits (8bpp only)
gamma
defaultVisual
maxHValue
maxVValue
virtualX
virtualY
displayWidth
frameX0
frameY0
frameX1
frameY1
zoomLocked
modePool
modes
currentMode
progClock (TRUE if clock is programmable)
chipset
ramdac
clockchip
numClocks (if not programmable)
clock[] (if not programmable)
videoRam
biosBase
memBase
memClk
driverPrivate
chipID
chipRev
pointer xf86LoadSubModule(ScrnInfoPtr pScrn, const char *name):
Load a module that a driver depends on. This function
loads the module name as a sub module of the driver. The
return value is a handle identifying the new module. If
the load fails, the return value will be NULL. If a
driver needs to explicitly unload a module it has loaded
in this way, the return value must be saved and passed to
UnloadSubModule() when unloading.
void UnloadSubModule(pointer module)
Unloads the module referenced by module. module should
be a pointer returned previously by xf86LoadSubModule().
5.13 Cleaning up Unused Drivers
At this point it is known which screens will be in use, and which drivers are
being used. Unreferenced drivers (and modules they may have loaded) are
unloaded here.
5.14 Consistency Checks
The parameters that must be global to the server, like pixmap formats, bitmap
bit order, bitmap scanline unit and image byte order are compared for each of
the screens. If a mismatch is found, the server exits with an appropriate
message.
5.15 Check of Resource Control is Needed
Determine if resource access control is needed. This is the case if more
than one screen is used. If necessary the RAC wrapper module is loaded.
5.16 AddScreen (ScreenInit)
At this point, the valid screens are known. AddScreen() is called for each
of them, passing ChipScreenInit() as the argument. AddScreen() is a DIX
function that allocates a new screenInfo.screen[] entry (aka pScreen), and
does some basic initialisation of it. It then calls the ChipScreenInit()
function, with pScreen as one of its arguments. If ChipScreenInit() returns
FALSE, AddScreen() returns -1. Otherwise it returns the index of the screen.
AddScreen() should only fail because of programming errors or failure to
allocate resources (like memory). All configuration problems should be
detected BEFORE this point.
Bool ChipScreenInit(int index, ScreenPtr pScreen,
int argc, char **argv)
This is called at the start of each server generation.
Fill in all of pScreen, possibly doing some of this by
calling ScreenInit functions from other layers like mi,
framebuffers (cfb, etc), and extensions.
Decide which operations need to be placed under resource
access control. The classes of operations are the frame
buffer operations (RAC_FB), the pointer operations
(RAC_CURSOR), the viewport change operations (RAC_VIEW-
PORT) and the colormap operations (RAC_COLORMAP). Any
operation that requires resources which might be disabled
during OPERATING state should be set to use RAC. This
can be specified separately for memory and IO resources
(the racMemFlags and racIoFlags fields of the ScrnInfoRec
respectively).
Map any video memory or other memory regions.
Save the video card state. Enough state must be saved so
that the original state can later be restored.
Initialise the initial video mode. The ScrnInfoRec's
vtSema field should be set to TRUE just prior to changing
the video hardware's state.
The ChipScreenInit() function (or functions from other layers that it calls)
should allocate entries in the ScreenRec's devPrivates area by calling Allo-
cateScreenPrivateIndex() if it needs per-generation storage. Since the
ScreenRec's devPrivates information is cleared for each server generation,
this is the correct place to initialise it.
After AddScreen() has successfully returned, the following ScrnInfoRec fields
are initialised:
pScreen
racMemFlags
racIoFlags
The ChipScreenInit() function should initialise the CloseScreen and Save-
Screen fields of pScreen. The old value of pScreen->CloseScreen should be
saved as part of the driver's per-screen private data, allowing it to be
called from ChipCloseScreen(). This means that the existing CloseScreen()
function is wrapped.
5.17 Finalising RAC Initialisation
After all the ChipScreenInit() functions have been called, each screen has
registered its RAC requirements. This information is used to determine which
shared resources are requested by more than one driver and set the access
functions accordingly. This is done following these rules:
1. The sharable resources registered by each entity are compared. If a
resource is registered by more than one entity the entity will be
marked to indicate that it needs to share this resources type (IO or
MEM).
2. A resource marked ``disabled'' during OPERATING state will be ignored
entirely.
3. A resource marked ``unused'' will only conflict with an overlapping
resource of an other entity if the second is actually in use during
OPERATING state.
4. If an ``unused'' resource was found to conflict but the entity does not
use any other resource of this type the entire resource type will be
disabled for that entity.
5.18 Finishing InitOutput()
At this point InitOutput() is finished, and all the screens have been setup
in their initial video mode.
5.19 Mode Switching
When a SwitchMode event is received, ChipSwitchMode() is called (when it
exists):
Bool ChipSwitchMode(int index, DisplayModePtr mode, int flags)
Initialises the new mode for the screen identified by
index;. The viewport may need to be adjusted also.
5.20 Changing Viewport
When a Change Viewport event is received, ChipAdjustFrame() is called (when
it exists):
void ChipAdjustFrame(int index, int x, int y, int flags)
Changes the viewport for the screen identified by index;.
5.21 VT Switching
When a VT switch event is received, xf86VTSwitch() is called. xf86VTSwitch()
does the following:
On ENTER:
o enable port I/O access
o save and initialise the bus/resource state
o enter the SETUP server state
o calls ChipEnterVT() for each screen
o enter the OPERATING server state
o validate GCs
o Restore fb from saved pixmap for each screen
o Enable all input devices
On LEAVE:
o Save fb to pixmap for each screen
o validate GCs
o enter the SETUP server state
o calls ChipLeaveVT() for each screen
o disable all input devices
o restore bus/resource state
o disables port I/O access
Bool ChipEnterVT(int index, int flags)
This function should map memory regions, initialise the
current video mode and initialise the viewport, turn on
the HW cursor if appropriate, etc.
Should it re-save the video state before initialising the
video mode?
void ChipLeaveVT(int index, int flags)
This function should restore the saved video state and
unmap the memory regions. If appropriate it should also
turn off the HW cursor, and invalidate any pixmap/font
caches.
Other layers may wrap the ChipEnterVT() and ChipLeaveVT() functions if they
need to take some action when these events are received.
5.22 End of server generation
At the end of each server generation, the DIX layer calls ChipCloseScreen()
for each screen:
Bool ChipCloseScreen(int index, ScreenPtr pScreen)
This function should restore the saved video state and
unmap the memory regions.
It should also free per-screen data structures allocated
by the driver. Note that the persistent data held in the
ScrnInfoRec's driverPrivate field should not be freed
here because it is needed by subsequent server genera-
tions.
The ScrnInfoRec's vtSema field should be set to FALSE
once the video HW state has been restored.
Before freeing the per-screen driver data the saved Clos-
eScreen value should be restored to pScreen->CloseScreen,
and that function should be called after freeing the
data.
6. Optional Driver Functions
The functions outlined here can be called from the XFree86 common layer, but
their presence is optional.
6.1 Mode Validation
When a mode validation helper supplied by the XFree86-common layer is being
used, it can be useful to provide a function to check for hw specific mode
constraints:
ModeStatus ChipValidMode(int index, DisplayModePtr mode,
Bool verbose, int flags)
Check the passed mode for hw-specific constraints, and
return the appropriate status value.
6.2 Free screen data
When a screen is deleted prior to the completion of the ScreenInit phase the
ChipFreeScreen() function is called when defined.
void ChipFreeScreen(int scrnindex, int flags)
Free any driver-allocated data that may have been allo-
cated up to and including an unsuccessful Chip-
ScreenInit() call. This would predominantly be data
allocated by ChipPreInit() that persists across server
generations. It would include the driverPrivate, and any
``privates'' entries that modules may have allocated.
7. Recommended driver functions
The functions outlined here are for internal use by the driver only. They
are entirely optional, and are never accessed directly from higher layers.
The sample function declarations shown here are just examples. The interface
(if any) used is up to the driver.
7.1 Save
Save the video state. This could be called from ChipScreenInit() and (possi-
bly) ChipEnterVT().
void ChipSave(ScrnInfoPtr pScrn)
Saves the current state. This will only be saving pre-
server states or states before returning to the server.
There is only one current saved state per screen and it
is stored in private storage in the screen.
7.2 Restore
Restore the original video state. This could be called from the
ChipLeaveVT() and ChipCloseScreen() functions.
void ChipRestore(ScrnInfoPtr pScrn)
Restores the saved state from the private storage. Usu-
ally only used for restoring text modes.
7.3 Initialise Mode
Initialise a video mode. This could be called from the ChipScreenInit(),
ChipSwitchMode() and ChipEnterVT() functions.
Bool ChipModeInit(ScrnInfoPtr pScrn, DisplayModePtr mode)
Programs the hardware for the given video mode.
8. Data and Data Structures
8.1 Command line data
Command line options are typically global, and are stored in global vari-
ables. These variables are read-only and are available to drivers via a
function call interface. Most of these command line values are processed via
helper functions to ensure that they are treated consistently by all drivers.
The other means of access is provided for cases where the supplied helper
functions might not be appropriate.
Some of them are:
xf86Verbose verbosity level
xf86Bpp -bpp from the command line
xf86Depth -depth from the command line
xf86Weight -weight from the command line
xf86Gamma -{r,g,b,}gamma from the command line
xf86FlipPixels -flippixels from the command line
xf86ProbeOnly -probeonly from the command line
defaultColorVisualClass -cc from the command line
If we ever do allow for screen-specific command line options, we may need to
rethink this.
These can be accessed in a read-only manner by drivers with the following
functions:
int xf86GetVerbosity()
Returns the value of xf86Verbose.
int xf86GetDepth()
Returns the -depth command line setting. If not set on
the command line, -1 is returned.
rgb xf86GetWeight()
Returns the -weight command line setting. If not set on
the command line, {0, 0, 0} is returned.
Gamma xf86GetGamma()
Returns the -gamma or -rgamma, -ggamma, -bgamma command
line settings. If not set on the command line, {0.0,
0.0, 0.0} is returned.
Bool xf86GetFlipPixels()
Returns TRUE if -flippixels is present on the command
line, and FALSE otherwise.
const char *xf86GetServerName()
Returns the name of the X server from the command line.
8.2 Data handling
Config file data contains parts that are global, and parts that are Screen
specific. All of it is parsed into data structures that neither the drivers
or most other parts of the server need to know about.
The global data is typically not required by drivers, and as such, most of it
is stored in the private xf86InfoRec.
The screen-specific data collected from the config file is stored in screen,
device, display, monitor-specific data structures that are separate from the
ScrnInfoRecs, with the appropriate elements/fields hooked into the ScrnIn-
foRecs as required. The screen config data is held in confScreenRec, device
data in the GDevRec, monitor data in the MonRec, and display data in the Dis-
pRec.
The XFree86 common layer's screen specific data (the actual data in use for
each screen) is held in the ScrnInfoRecs. As has been outlined above, the
ScrnInfoRecs are allocated at probe time, and it is the responsibility of the
Drivers' Probe() and PreInit() functions to finish filling them in based on
both data provided on the command line and data provided from the Config
file. The precedence for this is:
command line -> config file -> probed/default data
For most things in this category there are helper functions that the drivers
can use to ensure that the above precedence is consistently used.
As well as containing screen-specific data that the XFree86 common layer
(including essential parts of the server infrastructure as well as helper
functions) needs to access, it also contains some data that drivers use
internally. When considering whether to add a new field to the ScrnInfoRec,
consider the balance between the convenience of things that lots of drivers
need and the size/obscurity of the ScrnInfoRec.
Per-screen driver specific data that cannot be accommodated with the static
ScrnInfoRec fields is held in a driver-defined data structure, a pointer to
which is assigned to the ScrnInfoRec's driverPrivate field. This is per-
screen data that persists across server generations (as does the bulk of the
static ScrnInfoRec data). It would typically also include the video card's
saved state.
Per-screen data for other modules that the driver uses (for example, the XAA
module) that is reset for each server generation is hooked into the ScrnIn-
foRec through it's privates field.
Once it has stabilised, the data structures and variables accessible to video
drivers will be documented here. In the meantime, those things defined in
the xf86.h and xf86str.h files are visible to video drivers. Things defined
in xf86Priv.h and xf86Privstr.h are NOT intended to be visible to video
drivers, and it is an error for a driver to include those files.
8.3 Accessing global data
Some other global state information that the drivers may access via functions
is as follows:
Bool xf86ServerIsExiting()
Returns TRUE if the server is at the end of a generation
and is in the process of exiting, and FALSE otherwise.
Bool xf86ServerIsResetting()
Returns TRUE if the server is at the end of a generation
and is in the process of resetting, and FALSE otherwise.
Bool xf86ServerIsInitialising()
Returns TRUE if the server is at the beginning of a gen-
eration and is in the process of initialising, and FALSE
otherwise.
Bool xf86ServerIsOnlyProbing()
Returns TRUE if the -probeonly command line flag was
specified, and FALSE otherwise.
Bool xf86CaughtSignal()
Returns TRUE if the server has caught a signal, and FALSE
otherwise.
8.4 Allocating private data
A driver and any module it uses may allocate per-screen private storage in
either the ScreenRec (DIX level) or ScrnInfoRec (XFree86 common layer level).
ScreenRec storage persists only for a single server generation, and ScrnIn-
foRec storage persists across generations for the lifetime of the server.
The ScreenRec devPrivates data must be reallocated/initialised at the start
of each new generation. This is normally done from the ChipScreenInit()
function, and Init functions for other modules that it calls. Data allocated
in this way should be freed by the driver's ChipCloseScreen() functions, and
Close functions for other modules that it calls. A new devPrivates entry is
allocated by calling the AllocateScreenPrivateIndex() function.
int AllocateScreenPrivateIndex()
This function allocates a new element in the devPrivates
field of all currently existing ScreenRecs. The return
value is the index of this new element in the devPrivates
array. The devPrivates field is of type DevUnion:
typedef union _DevUnion {
pointer ptr;
long val;
unsigned long uval;
pointer (*fptr)(void);
} DevUnion;
which allows the element to be used for any of the above
types. It is commonly used as a pointer to data that the
caller allocates after the new index has been allocated.
This function will return -1 when there is an error allo-
cating the new index.
The ScrnInfoRec privates data persists for the life of the server, so only
needs to be allocated once. This should be done from the ChipPreInit() func-
tion, and Init functions for other modules that it calls. Data allocated in
this way should be freed by the driver's ChipFreeScreen() functions, and Free
functions for other modules that it calls. A new privates entry is allocated
by calling the xf86AllocateScrnInfoPrivateIndex() function.
int xf86AllocateScrnInfoPrivateIndex()
This function allocates a new element in the privates
field of all currently existing ScrnInfoRecs. The return
value is the index of this new element in the privates
array. The privates field is of type DevUnion:
typedef union _DevUnion {
pointer ptr;
long val;
unsigned long uval;
pointer (*fptr)(void);
} DevUnion;
which allows the element to be used for any of the above
types. It is commonly used as a pointer to data that the
caller allocates after the new index has been allocated.
This function will not return when there is an error
allocating the new index. When there is an error it will
cause the server to exit with a fatal error. The similar
function for allocation privates in the ScreenRec (Allo-
cateScreenPrivateIndex()) differs in this respect by
returning -1 when the allocation fails.
9. Keeping Track of Bus Resources
9.1 Theory of Operation
The XFree86 common layer has knowledge of generic access control mechanisms
for devices on certain bus systems (currently the PCI bus) as well as of
methods to enable or disable access to the buses itself. Furthermore it can
access information on resources decoded by these devices and if necessary
modify it.
When first starting the Xserver collects all this information, saves it for
restoration, checks it for consistency, and if necessary, corrects it.
Finally it disables all resources on a generic level prior to calling any
driver function.
When the Probe() function of each driver is called the device sections are
matched against the devices found in the system. The driver may probe
devices at this stage that cannot be identified by using device independent
methods. Access to all resources that can be controlled in a device indepen-
dent way is disabled. The Probe() function should register all non-relocat-
able resources at this stage. If a resource conflict is found between exclu-
sive resources the driver will fail immediately. Optionally the driver might
specify an EntityInit(), EntityLeave() and EntityEnter() function.
EntityInit() can be used to disable any shared resources that are not con-
trolled by the generic access control functions. It is called prior to the
PreInit phase regardless if an entity is active or not. When calling the
EntityInit(), EntityEnter() and EntityLeave() functions the common level will
disable access to all other entities on a generic level. Since the common
level has no knowledge of device specific methods to disable access to
resources it cannot be guaranteed that certain resources are not decoded by
any other entity until the EntityInit() or EntityEnter() phase is finished.
Device drivers should therefore register all those resources which they are
going to disable. If these resources are never to be used by any driver
function they may be flagged ResInit so that they can be removed from the
resource list after processing all EntityInit() functions. EntityEnter()
should disable decoding of all resources which are not registered as exclu-
sive and which are not handled by the generic access control in the common
level. The difference to EntityInit() is that the latter one is only called
once during lifetime of the server. It can therefore be used to set up vari-
ables prior to disabling resources. EntityLeave() should restore the origi-
nal state when exiting the server or switching to a different VT. It also
needs to disable device specific access functions if they need to be disabled
on server exit or VT switch. The default state is to enable them before giv-
ing up the VT.
In PreInit() phase each driver should check if any sharable resources it has
registered during Probe() has been denied and take appropriate action which
could simply be to fail. If it needs to access resources it has disabled
during EntitySetup() it can do so provided it has registered these and will
disable them before returning from PreInit(). This also applies to all other
driver functions. Several functions are provided to request resource ranges,
register these, correct PCI config space and add replacements for the generic
access functions. Resources may be marked ``disabled'' or ``unused'' during
OPERATING stage. Although these steps could also be performed in
ScreenInit(), this is not desirable.
Following PreInit() phase the common level determines if resource access con-
trol is needed. This is the case if more than one screen is used. If neces-
sary the RAC wrapper module is loaded. In ScreenInit() the drivers can
decide which operations need to be placed under RAC. Available are the frame
buffer operations, the pointer operations and the colormap operations. Any
operation that requires resources which might be disabled during OPERATING
state should be set to use RAC. This can be specified separately for memory
and IO resources.
When ScreenInit() phase is done the common level will determine which shared
resources are requested by more than one driver and set the access functions
accordingly. This is done following these rules:
1. The sharable resources registered by each entity are compared. If a
resource is registered by more than one entity the entity will be
marked to need to share this resources type (IO or MEM).
2. A resource marked ``disabled'' during OPERATING state will be ignored
entirely.
3. A resource marked ``unused'' will only conflicts with an overlapping
resource of an other entity if the second is actually in use during
OPERATING state.
4. If an ``unused'' resource was found to conflict however the entity does
not use any other resource of this type the entire resource type will
be disabled for that entity.
The driver has the choice among different ways to control access to certain
resources:
1. It can rely on the generic access functions. This is probably the most
common case. Here the driver only needs to register any resource it is
going to use.
2. It can replace the generic access functions by driver specific ones.
This will mostly be used in cases where no generic access functions are
available. In this case the driver has to make sure these resources
are disabled when entering the PreInit() stage. Since the replacement
functions are registered in PreInit() the driver will have to enable
these resources itself if it needs to access them during this state.
The driver can specify if the replacement functions can control memory
and/or I/O resources separately.
3. The driver can enable resources itself when it needs them. Each driver
function enabling them needs to disable them before it will return.
This should be used if a resource which can be controlled in a device
dependent way is only required during SETUP state. This way it can be
marked ``unused'' during OPERATING state.
A resource which is decoded during OPERATING state however never accessed by
the driver should be marked unused.
Since access switching latencies are an issue during Xserver operation, the
common level attempts to minimize the number of entities that need to be
placed under RAC control. When a wrapped operation is called, the EnableAc-
cess() function is called before control is passed on. EnableAccess() checks
if a screen is under access control. If not it just establishes bus routing
and returns. If the screen needs to be under access control, EnableAccess()
determines which resource types (MEM, IO) are required. Then it tests if
this access is already established. If so it simply returns. If not it dis-
ables the currently established access, fixes bus routing and enables access
to all entities registered for this screen.
Whenever a mode switch or a VT-switch is performed the common level will
return to SETUP state.
9.2 Resource Types
Resource have certain properties. When registering resources each range is
accompanied by a flag consisting of the ORed flags of the different proper-
ties the resource has. Each resource range may be classified according to
o its physical properties i.e., if it addresses memory (ResMem) or I/O
space (ResIo),
o if it addresses a block (ResBlock) or sparse (ResSparse) range,
o its access properties.
There are two known access properties:
o ResExclusive for resources which may not be shared with any other device
and
o ResShared for resources which can be disabled and therefore can be
shared.
If it is necessary to test a resource against any type a generic access type
ResAny is provided. If this is set the resource will conflict with any
resource of a different entity intersecting its range. Further it can be
specified that a resource is decoded however never used during any stage
(ResUnused) or during OPERATING state (ResUnusedOpr). A resource only visi-
ble during the init functions (ie. EntityInit(), EntityEnter() and
EntityLeave() should be registered with the flag ResInit. A resource that
might conflict with background resource ranges may be flagged with ResBios.
This might be useful when registering resources ranges that were assigned by
the system Bios.
Several predefined resource lists are available for VGA and 8514/A resources
in common/xf86Resources.h.
9.3 Available Functions
The functions provided for resource management are listed in their order of
use in the driver.
9.3.1 Probe Phase
In this phase each driver detects those resources it is able to drive, cre-
ates an entity record for each of them, registers non-relocatable resources
and allocates screens and adds the resources to screens.
Two helper functions are provided for matching device sections in the
XF86Config file to the devices:
int xf86MatchPciInstances(const char *driverName, int vendorID,
SymTabPtr chipsets, PciChipsets *PCIchipsets,
GDevPtr *devList, int numDevs,
GDevPtr *devList, int numDevs, DriverPtr drvp,
int **foundEntities)
This function finds matches between PCI cards that a
driver supports and config file device sections. It is
intended for use in the ChipProbe() function of drivers
for PCI cards. Only probed PCI devices with a vendor ID
matching vendorID are considered. devList and numDevs
are typically those found from calling xf86MatchDevice(),
and represent the active config file device sections rel-
evant to the driver. PCIchipsets is a table that pro-
vides a mapping between the PCI device IDs, the driver's
internal chipset tokens and a list of fixed resources.
When a device section doesn't have a BusID entry it can
only match the primary video device. Secondary devices
are only matched with device sections that have a match-
ing BusID entry.
Once the preliminary matches have been found, a final
match is confirmed by checking if the chipset override,
ChipID override or probed PCI chipset type match one of
those given in the chipsets and PCIchipsets lists. The
PCIchipsets list includes a list of the PCI device IDs
supported by the driver. The list should be terminated
with an entry with PCI ID -1". The chipsets list is a
table mapping the driver's internal chipset tokens to
names, and should be terminated with a NULL entry. Only
those entries with a corresponding entry in the PCI-
chipsets list are considered. The order of precedence
is: config file chipset, config file ChipID, probed PCI
device ID.
In cases where a driver handles PCI chipsets with more
than one vendor ID, it may set vendorID to 0, and OR each
devID in the list with (the vendor ID << 16).
Entity index numbers for confirmed matches are returned
as an array via foundEntities. The PCI information,
chipset token and device section for each match are found
in the EntityInfoRec referenced by the indices.
The function return value is the number of confirmed
matches. A return value of -1 indicates an internal
error. The returned foundEntities array should be freed
by the driver with xfree() when it is no longer needed in
cases where the return value is greater than zero.
int xf86MatchIsaInstances(const char *driverName,
SymTabPtr chipsets, IsaChipsets *ISAchipsets,
DriverPtr drvp, FindIsaDevProc FindIsaDevice,
GDevPtr *devList, int numDevs, int **foundEntities)
This function finds matches between ISA cards that a
driver supports and config file device sections. It is
intended for use in the ChipProbe() function of drivers
for ISA cards. devList and numDevs are typically those
found from calling xf86MatchDevice(), and represent the
active config file device sections relevant to the
driver. ISAchipsets is a table that provides a mapping
between the driver's internal chipset tokens and the
resource classes. FindIsaDevice is a driver-provided
function that probes the hardware and returns the chipset
token corresponding to what was detected, and -1 if noth-
ing was detected.
If the config file device section contains a chipset
entry, then it is checked against the chipsets list.
When no chipset entry is present, the FindIsaDevice func-
tion is called instead.
Entity index numbers for confirmed matches are returned
as an array via foundEntities. The chipset token and
device section for each match are found in the EntityIn-
foRec referenced by the indices.
The function return value is the number of confirmed
matches. A return value of -1 indicates an internal
error. The returned foundEntities array should be freed
by the driver with xfree() when it is no longer needed in
cases where the return value is greater than zero.
These two helper functions make use of several core functions that are avail-
able at the driver level:
Bool xf86ParsePciBusString(const char *busID, int *bus,
int *device, int *func)
Takes a BusID string, and if it is in the correct format,
returns the PCI bus, device, func values that it indi-
cates. The format of the string is expected to be
"PCI:bus:device:func" where each of `bus', `device' and
`func' are decimal integers. The ":func" part may be
omitted, and the func value assumed to be zero, but this
isn't encouraged. The "PCI" prefix may also be omitted.
The prefix "AGP" is currently equivalent to the "PCI"
prefix. If the string isn't a valid PCI BusID, the
return value is FALSE.
Bool xf86ComparePciBusString(const char *busID, int bus,
int device, int func)
Compares a BusID string with PCI bus, device, func val-
ues. If they match TRUE is returned, and FALSE if they
don't.
Bool xf86ParseIsaBusString(const char *busID)
Compares a BusID string with the ISA bus ID string ("ISA"
or "ISA:"). If they match TRUE is returned, and FALSE if
they don't.
Bool xf86CheckPciSlot(int bus, int device, int func)
Checks if the PCI slot bus:device:func has been claimed.
If so, it returns FALSE, and otherwise TRUE.
int xf86ClaimPciSlot(int bus, int device, int func, DriverPtr drvp,
int chipset, GDevPtr dev, Bool active)
This function is used to claim a PCI slot, allocate the
associated entity record and initialise their data struc-
tures. The return value is the index of the newly allo-
cated entity record, or -1 if the claim fails. This
function should always succeed if xf86CheckPciSlot()
returned TRUE for the same PCI slot.
Bool xf86IsPrimaryPci(void)
This function returns TRUE if the primary card is a PCI
device, and FALSE otherwise.
int xf86ClaimIsaSlot(DriverPtr drvp, int chipset,
GDevPtr dev, Bool active)
This allocates an entity record entity and initialise the
data structures. The return value is the index of the
newly allocated entity record.
Bool xf86IsPrimaryIsa(void)
This function returns TRUE if the primary card is an ISA
(non-PCI) device, and FALSE otherwise.
Two helper functions are provided to aid configuring entities:
Bool xf86ConfigActivePciEntity(ScrnInfoPtr pScrn, int entityIndex,
PciChipsets *p_chip, resList res,
EntityProc init, EntityProc enter,
EntityProc leave, pointer private)
Bool xf86ConfigActiveIsaEntity(ScrnInfoPtr pScrn, int entityIndex,
IsaChipsets *i_chip, resList res,
EntityProc init, EntityProc enter,
EntityProc leave, pointer private)
These functions are used to register the non-relocatable
resources for an entity, and the optional entity-specific
Init, Enter and Leave functions. Usually the list of
fixed resources is obtained from the Isa/PciChipsets
lists. However an additional list of resources may be
passed. Generally this is not required. The return
value is TRUE when successful. The init, enter, leave
functions are defined as follows:
typedef void (*EntityProc)(int entityIndex,
pointer private)
They are passed the entity index and a pointer to a pri-
vate scratch area. This are can be set up during Probe()
and its address can be passed to xf86ConfigActiveIsaEn-
tity() xf86ConfigActivePciEntity() as the last argument.
These two helper functions make use of several core functions that are avail-
able at the driver level:
void xf86ClaimFixedResources(resList list, int entityIndex)
This function registers the non-relocatable resources
which cannot be disabled and which therefore would cause
the server to fail immediately if they were found to con-
flict. It also records non-relocatable but sharable
resources for processing after the Probe() phase.
Bool xf86SetEntityFuncs(int entityIndex, EntityProc init,
EntityProc enter, EntityProc leave, pointer)
This function registers with an entity the init, enter,
leave functions along with the pointer to their private
area.
void xf86AddEntityToScreen(ScrnInfoPtr pScrn, int entityIndex)
This function associates the entity referenced by enti-
tyIndex with the screen.
9.3.2 PreInit Phase
During this phase the remaining resource should be registered. PreInit()
should call xf86GetEntityInfo() To obtain a pointer to an EntityInfoRec for
each entity it is able to drive and check if any resource are listed in its
resources field. If resources registered in the Probe phase have been
rejected in the post-Probe phase (resources == NULL), then the driver should
decide if it can continue without using these or if it should fail.
EntityInfoPtr xf86GetEntityInfo(int entityIndex)
This function returns a pointer to the EntityInfoRec ref-
erenced by entityIndex. The returned EntityInfoRec
should be freed with xfree() when no longer needed.
Several functions are provided to simplify resource registration:
Bool xf86IsEntityPrimary(int entityIndex)
This function returns TRUE if the entity referenced by
entityIndex is the display device that primary display
device (i.e., the one initialised at boot time and used
in text mode).
Bool xf86IsScreenPrimary(int scrnIndex)
This function returns TRUE if the primary entity is reg-
istered with the screen referenced by scrnIndex.
pciVideoPtr xf86GetPciInfoForEntity(int entityIndex)
This function returns a pointer to the pciVideoRec for
the specified entity. If the entity is not a PCI device,
NULL is returned.
The primary function for registration of resources is:
resPtr xf86RegisterResources(int entityIndex, resList list,
int access)
This function tries to register the resources in list.
If list is NULL it tries to determine the resources auto-
matically. This only works for entities that provide a
generic way to read out the resource ranges they decode.
So far this is only the case for PCI devices. By default
the PCI resources are registered as shared (ResShared) if
the driver wants to set a different access type it can do
so by specifying the access flags in the third argument.
A value of 0 means to use the default settings. If for
any reason the resource broker is not able to register
some of the requested resources the function will return
a pointer to a list of the failed ones. In this case the
driver may be able to move the resource to different
locations. In case of PCI bus entities this is done by
passing the list of failed resources to xf86ReallocateP-
ciResources(). When the registration succeeds, the
return value is NULL.
resPtr xf86ReallocatePciResources(int entityIndex, resPtr pRes)
This function takes a list of PCI resources that need to
be reallocated and returns a list of the reallocated
resource. This list needs to be passed to xf86Register-
Resources() again to be registered with the broker. If
the reallocation fails, NULL is returned.
Two functions are provided to obtain a resource range of a given type:
resRange xf86GetBlock(long type, memType size,
memType window_start, memType window_end,
memType align_mask, resPtr avoid)
This function tries to find a block range of size size
and type type in a window bound by window_start and win-
dow_end with the alignment specified in align_mask.
Optionally a list of resource ranges which should be
avoided within the window can be supplied. On failure a
zero-length range of type ResEnd will be returned.
resRange xf86GetSparse(long type, memType fixed_bits,
memType decode_mask, memType address_mask,
resPtr avoid)
This function is like the previous one, but attempts to
find a sparse range instead of a block range. Here three
values have to be specified: the address_mask which marks
all bits of the mask part of the address, the decode_mask
which masks out the bits which are hardcoded and are
therefore not available for relocation and the values of
the fixed bits. The function tries to find a base that
satisfies the given condition. If the function fails it
will return a zero range of type ResEnd. Optionally it
might be passed a list of resource ranges to avoid.
Some PCI devices are broken in the sense that they return invalid size infor-
mation for a certain resource. In this case the driver can supply the cor-
rect size and make sure that the resource range allocated for the card is
large enough to hold the address range decoded by the card. The function
xf86FixPciResource() can be used to do this:
Bool xf86FixPciResource(int entityIndex, unsigned int prt,
CARD32 alignment, long type)
This function fixes a PCI resource allocation. The prt
parameter contains the number of the PCI base register
that needs to be fixed (0-5, and 6 for the BIOS base reg-
ister). The size is specified by the alignment. Since
PCI resources need to span an integral range of the size
2^n the alignment also specifies the number of addresses
that will be decoded. If the driver specifies a type
mask it can override the default type for PCI resources
which is ResShared. The resource broker needs to know
that to find a matching resource range. This function
should be called before calling xf86RegisterResources().
The return value is TRUE when the function succeeds.
Bool xf86CheckPciMemBase(pciVideoPtr pPci, memType base)
This function checks that the memory base address speci-
fied matches one of the PCI base address register values
for the given PCI device. This is mostly used to check
that an externally provided base address (e.g., from a
config file) matches an actual value allocated to a
device.
The driver may replace the generic access control functions for an entity by
it's own ones. This is done with the xf86SetAccessFuncs():
void xf86SetAccessFuncs(EntityInfoPtr pEnt, xf86AccessPtr p_io,
xf86AccessPtr p_mem, xf86AccessPtr p_io_mem,
xf86AccessPtr *ppAccessOld)
The driver can pass three functions: one for I/O access,
one for memory access and one for combined memory and I/O
access. If the memory access and combined access func-
tions are identical the common level assumes that the
memory access cannot be controlled independently of I/O
access, if the I/O access function and the combined
access functions are the same it is assumed that I/O can
not be controlled independently. If memory and I/O have
to be controlled together all three values should be the
same. If a non NULL value is passed as fifth argument it
is interpreted as an address where to store the old
access record. If the fifth argument is NULL it will be
assumed that the generic access should be enabled before
replacing the access functions. Otherwise it will be
disabled. The driver may enable them itself using the
returned values. It should do this from his replacement
access functions as the generic access may be disabled by
the common level on certain occasions. If replacement
functions are specified they must control all resources
of the specific type registered for the entity.
To find out if specific resource range is conflicting with another resource
the xf86ChkConflict() function may be used:
memType xf86ChkConflict(resRange *rgp, int entityIndex)
This function checks if the resource range rgp of for the
specified entity conflicts with with another resource.
If it a conflict is found, the address of the start of
the conflict is returned. The return value is zero when
there is no conflict.
The OPERATING state properties of previously registered fixed resources can
be set with the xf86SetOperatingState() function:
resPtr xf86SetOperatingState(resList list, int entityIndex,
int mask)
This function is used to set the status of a resource
during OPERATING state. list holds a list to which mask
is to be applied. The parameter mask may have the value
ResUnusedOpr and ResDisableOpr. The first one should be
used if a resource isn't used by the driver during OPER-
ATING state although it is decoded by the device, while
the latter one indicates that the resource is not decoded
during OPERATING state. Note that the resource ranges
have to match those specified during registration. If a
range has been specified starting at A and ending at B
and suppose C us a value satisfying A < C < B one may not
specify the resource range (A,B) by splitting it into two
ranges (A,C) and (C,B).
The following two functions are provided for special cases:
void xf86RemoveEntityFromScreen(ScrnInfoPtr pScrn, int entityIndex)
This function may be used to remove an entity from a
screen. This only makes sense if a screen has more than
one entity assigned or the screen is to be deleted. No
test is made if the screen has any entities left.
void xf86DeallocateResourcesForEntity(int entityIndex, long type)
This function deallocates all resources of a given type
registered for a certain entity from the resource broker
list.
9.3.3 ScreenInit Phase
All that is required in this phase is to setup the RAC flags. Note that it
is also permissible to set these flags up in the PreInit phase. The RAC
flags are held in the racIoFlags and racMemFlags fields of the ScrnInfoRec
for each screen. They specify which graphics operations might require the
use of shared resources. This can be specified separately for memory and I/O
resources. The available flags are defined in rac/xf86RAC.h. They are:
RAC_FB
for framebuffer operations (including hw acceleration)
RAC_CURSOR
for Cursor operations (??? I'm not sure if we need this for SW cur-
sor it depends on which level the sw cursor is drawn)
RAC_COLORMAP
for colormap operations
RAC_VIEWPORT
for the call to ChipAdjustFrame()
The flags are ORed together.
10. Config file ``Option'' entries
Option entries are permitted in most sections and subsections of the config
file. There are two forms of option entries:
Option "option-name"
A boolean option.
Option "option-name" "option-value"
An option with an arbitrary value.
The option entries are handled by the parser, and a list of the parsed
options is included with each of the appropriate data structures that the
drivers have access to. The data structures used to hold the option informa-
tion are opaque to the driver, and a driver must not access the option data
directly. Instead, the common layer provides a set of functions that may be
used to access, check and manipulate the option data.
First, the low level option handling functions. In most cases drivers would
not need to use these directly.
pointer xf86FindOption(pointer options, const char *name)
Takes a list of options and an option name, and returns a
handle for the first option entry in the list matching
the name. Returns NULL if no match is found.
char *xf86FindOptionValue(pointer options, const char *name)
Takes a list of options and an option name, and returns
the value associated with the first option entry in the
list matching the name. If the matching option has no
value, an empty string ("") is returned. Returns NULL if
no match is found.
void xf86MarkOptionUsed(pointer option)
Takes a handle for an option, and marks that option as
used.
void xf86MarkOptionUsedByName(pointer options, const char *name)
Takes a list of options and an option name and marks the
first option entry in the list matching the name as used.
Next, the higher level functions that most drivers would use.
void xf86CollectOptions(ScrnInfoPtr pScrn, pointer extraOpts)
Collect the options from each of the config file sections
used by the screen (pScrn) and return the merged list as
pScrn->options. This function requires that pScrn->conf-
Screen, pScrn->display, pScrn->monitor, pScrn->numEnti-
ties, and pScrn->entityList are initialised. extraOpts
may optionally be set to an additional list of options to
be combined with the others. The order of precedence for
options is extraOpts, display, confScreen, monitor,
device.
void xf86ProcessOptions(int scrnIndex, pointer options,
OptionInfoPtr optinfo)
Processes a list of options according to the information
in the array of OptionInfoRecs (optinfo). The resulting
information is stored in the value fields of the appro-
priate optinfo entries. The found fields are set to TRUE
when an option with a value of the correct type if found,
and FALSE otherwise. The type field is used to determine
the expected value type for each option. Each option in
the list of options for which there is a name match (but
not necessarily a value type match) is marked as used.
Warning messages are printed when option values don't
match the types specified in the optinfo data.
NOTE: If this function is called before a driver's screen
number is known (e.g., from the ChipProbe() function) a
scrnIndex value of -1 should be used.
The OptionInfoRec is defined as follows:
typedef struct {
double freq;
int units;
} OptFrequency;
typedef union {
unsigned long num;
char * str;
double realnum;
Bool bool;
OptFrequency freq;
} ValueUnion;
typedef enum {
OPTV_NONE = 0,
OPTV_INTEGER,
OPTV_STRING, /* a non-empty string */
OPTV_ANYSTR, /* Any string, including an empty one */
OPTV_REAL,
OPTV_BOOLEAN,
OPTV_FREQ
} OptionValueType;
typedef enum {
OPTUNITS_HZ = 1,
OPTUNITS_KHZ,
OPTUNITS_MHZ
} OptFreqUnits;
typedef struct {
int token;
const char* name;
OptionValueType type;
ValueUnion value;
Bool found;
} OptionInfoRec, *OptionInfoPtr;
OPTV_FREQ can be used for options values that are fre-
quencies. These values are a floating point number with
an optional unit name appended. The unit name can be one
of "Hz", "kHz", "k", "MHz", "M". The multiplier associ-
ated with the unit is stored in freq.units, and the
scaled frequency is stored in freq.freq. When no unit is
specified, freq.units is set to 0, and freq.freq is
unscaled.
Typical usage is to setup a static array of OptionIn-
foRecs with the token, name, and type fields initialised.
The value and found fields get set by xf86ProcessOp-
tions(). For cases where the value parsing is more com-
plex, the driver should specify OPTV_STRING, and parse
the string itself. An example of using this option han-
dling is included in the Sample Driver (section 20., page
1) section.
void xf86ShowUnusedOptions(int scrnIndex, pointer options)
Prints out warning messages for each option in the list
of options that isn't marked as used. This is intended
to show options that the driver hasn't recognised. It
would normally be called near the end of the Chip-
ScreenInit() function, but only when
serverGeneration == 1.
OptionInfoPtr xf86TokenToOptinfo(OptionInfoPtr table, int token)
Returns a pointer to the OptionInfoRec in table with a
token field matching token. Returns NULL if no match is
found.
Bool xf86IsOptionSet(OptionInfoPtr table, int token)
Returns the found field of the OptionInfoRec in table
with a token field matching token. This can be used for
options of all types. Note that for options of type
OPTV_BOOLEAN, it isn't sufficient to check this to deter-
mine the value of the option. Returns FALSE if no match
is found.
char *xf86GetOptValString(OptionInfoPtr table, int token)
Returns the value.str field of the OptionInfoRec in table
with a token field matching token. Returns NULL if no
match is found.
Bool xf86GetOptValInteger(OptionInfoPtr table, int token,
int *value)
Returns via *value the value.num field of the OptionIn-
foRec in table with a token field matching token. *value
is only changed when a match is found so it can be safely
initialised with a default prior to calling this func-
tion. The function return value is as for xf86IsOption-
Set().
Bool xf86GetOptValULong(OptionInfoPtr table, int token,
unsigned long *value)
Like xf86GetOptValInteger(), except the value is treated
as an unsigned long.
Bool xf86GetOptValReal(OptionInfoPtr table, int token,
double *value)
Like xf86GetOptValInteger(), except that value.realnum is
used.
Bool xf86GetOptValFreq(OptionInfoPtr table, int token,
OptFreqUnits expectedUnits, double *value)
Like xf86GetOptValInteger(), except that the value.freq
data is returned. The frequency value is scaled to the
units indicated by expectedUnits. The scaling is exact
when the units were specified explicitly in the option's
value. Otherwise, the expectedUnits field is used as a
hint when doing the scaling. In this case, values larger
than 1000 are assumed to have be specified in the next
smallest units. For example, if the Option value is
"10000" and expectedUnits is OPTUNITS_MHZ, the value
returned is 10.
Bool xf86GetOptValBool(OptionInfoPtr table, int token, Bool *value)
This function is used to check boolean options
(OPTV_BOOLEAN). If the function return value is FALSE,
it means the option wasn't set. Otherwise *value is set
to the boolean value indicated by the option's value. No
option value is interpreted as TRUE. Option values mean-
ing TRUE are "1", "yes", "on", "true", and option values
meaning FALSE are "0", "no", "off", "false". Option
names both with the "no" prefix in their names, and with
that prefix removed are also checked and handled in the
obvious way. *value is not changed when the option isn't
present. It should normally be set to a default value
before calling this function.
Bool xf86ReturnOptValBool(OptionInfoPtr table, int token, Bool def)
This function is used to check boolean options
(OPTV_BOOLEAN). If the option is set, its value is
returned. If the options is not set, the default value
specified by def is returned. The option interpretation
is the same as for xf86GetOptValBool().
int xf86NameCmp(const char *s1, const char *s2)
This function should be used when comparing strings from
the config file with expected values. It works like str-
cmp(), but is not case sensitive and space, tab, and `_'
characters are ignored in the comparison. The use of
this function isn't restricted to parsing option values.
It may be used anywhere where this functionality
required.
11. Modules, Drivers, Include Files and Interface Issues
NOTE: this section is incomplete.
11.1 Include files
The following include files are typically required by video drivers:
All drivers should include these:
"xf86.h"
"xf86_OSproc.h"
"xf86_ansic.h"
"xf86Resources.h"
Wherever inb/outb (and related things) are used the following
should be included:
"compiler.h"
Drivers that need to access PCI vendor/device definitions need
this:
"xf86PciInfo.h"
Drivers that need to access the PCI config space need this:
"xf86Pci.h"
Drivers that initialise a SW cursor need this:
"mipointer.h"
All drivers implementing backing store need this:
"mibstore.h"
All drivers using the mi colourmap code need this:
"micmap.h"
If a driver uses the vgahw module, it needs this:
"vgaHW.h"
Drivers supporting VGA or Hercules monochrome screens need:
"xf1bpp.h"
Drivers supporting VGA or EGC 16-colour screens need:
"xf4bpp.h"
Drivers using cfb need:
#define PSZ 8
#include "cfb.h"
#undef PSZ
Drivers supporting bpp 16, 24 or 32 with cfb need one or more of:
"cfb16.h"
"cfb24.h"
"cfb32.h"
If a driver uses XAA, it needs these:
"xaa.h"
"xaalocal.h"
If a driver uses the fb manager, it needs this:
"xf86fbman.h"
Non-driver modules should include "xf86_ansic.h" to get the correct wrapping
of ANSI C/libc functions.
All modules must NOT include any system include files, or the following:
"xf86Priv.h"
"xf86Privstr.h"
"xf86_libc.h"
"xf86_OSlib.h"
"Xos.h"
or any other include files with ``priv'' in their name.
12. Offscreen Memory Manager
Management of offscreen video memory may be handled by the XFree86 frame-
buffer manager. Once the offscreen memory manager is running, drivers or
extensions may allocate, free or resize areas of offscreen video memory using
the following functions (definitions taken from xf86fbman.h):
typedef struct _FBArea {
ScreenPtr pScreen;
BoxRec box;
int granularity;
void (*MoveAreaCallback)(struct _FBArea*, struct _FBArea*)
void (*RemoveAreaCallback)(struct _FBArea*)
DevUnion devPrivate;
} FBArea, *FBAreaPtr;
typedef void (*MoveAreaCallbackProcPtr)(FBAreaPtr from, FBAreaPtr to)
typedef void (*RemoveAreaCallbackProcPtr)(FBAreaPtr)
FBAreaPtr xf86AllocateOffscreenArea (
ScreenPtr pScreen,
int width, int height,
int granularity,
MoveAreaCallbackProcPtr MoveAreaCallback,
RemoveAreaCallbackProcPtr RemoveAreaCallback,
pointer privData
)
void xf86FreeOffscreenArea (FBAreaPtr area)
Bool xf86ResizeOffscreenArea (
FBAreaPtr area
int w, int h
)
The function:
Bool xf86FBManagerRunning(ScreenPtr pScreen)
can be used by an extension to check if the driver has initialized the memory
manager. The manager is not available if this returns FALSE and the func-
tions above will all fail.
xf86AllocateOffscreenArea() can be used to request a rectangle of dimensions
width x height (in pixels) from unused offscreen memory. granularity speci-
fies that the leftmost edge of the rectangle must lie on some multiple of
granularity pixels. A granularity of zero means the same thing as a granu-
larity of one - no alignment preference. A MoveAreaCallback can be provided
to notify the requester when the offscreen area is moved. If no MoveArea-
Callback is supplied then the area is considered to be immovable. The priv-
Data field will be stored in the manager's internal structure for that allo-
cated area and will be returned to the requester in the FBArea passed via the
MoveAreaCallback. An optional RemoveAreaCallback is provided. If the driver
provides this it indicates that the area should be allocated with a lower
priority. Such an area may be removed when a higher priority request (one
that doesn't have a RemoveAreaCallback) is made. When this function is
called, the driver will have an opportunity to do whatever cleanup it needs
to do to deal with the loss of the area, but it must finish its cleanup
before the function exits since the offscreen memory manager will free the
area immediately after.
xf86AllocateOffscreenArea() returns NULL if it was unable to allocate the
requested area. When no longer needed, areas should be freed with xf86Free-
OffscreenArea().
xf86ResizeOffscreenArea() resizes an existing FBArea. xf86ResizeOff-
screenArea() returns TRUE if the resize was successful. If xf86ResizeOff-
screenArea() returns FALSE, the original FBArea is left unmodified. Resizing
an area maintains the area's original granularity, devPrivate, and MoveArea-
Callback. xf86ResizeOffscreenArea() has considerably less overhead than
freeing the old area then reallocating the new size, so it should be used
whenever possible.
The function:
Bool xf86QueryLargestOffscreenArea(
ScreenPtr pScreen,
int *width, int *height,
int granularity,
int preferences,
int priority
)
is provided to query the width and height of the largest single FBArea allo-
catable given a particular priority. preferences can be one of the following
to indicate whether width, height or area should be considered when determin-
ing which is the largest single FBArea available.
FAVOR_AREA_THEN_WIDTH
FAVOR_AREA_THEN_HEIGHT
FAVOR_WIDTH_THEN_AREA
FAVOR_HEIGHT_THEN_AREA
priority is one of the following:
PRIORITY_LOW
Return the largest block available without stealing any-
one else's space. This corresponds to the priority of
allocating a FBArea when a RemoveAreaCallback is pro-
vided.
PRIORITY_NORMAL
Return the largest block available if it is acceptable to
steal a lower priority area from someone. This corre-
sponds to the priority of allocating a FBArea without
providing a RemoveAreaCallback.
PRIORITY_EXTREME
Return the largest block available if all FBAreas that
aren't locked down were expunged from memory first. This
corresponds to any allocation made directly after a call
to xf86PurgeUnlockedOffscreenAreas().
The function:
Bool xf86PurgeUnlockedOffscreenAreas(ScreenPtr pScreen)
is provided as an extreme method to free up offscreen memory. This will
remove all removable FBArea allocations.
Initialization of the XFree86 framebuffer manager is done via
Bool xf86InitFBManager(ScreenPtr pScreen, BoxPtr FullBox)
FullBox represents the area of the framebuffer that the manager is allowed to
manage. This is typically a box with a width of pScrn->displayWidth and a
height of as many lines as can be fit within the total video memory, however,
the driver can reserve areas at the extremities by passing a smaller area to
the manager.
xf86InitFBManager() must be called before XAA is initialized since XAA uses
the manager for it's pixmap cache.
An alternative function is provided to allow the driver to initialize the
framebuffer manager with a Region rather than a box.
Bool xf86InitFBManagerRegion(ScreenPtr pScreen,
RegionPtr FullRegion)
xf86InitFBManagerRegion(), unlike xf86InitFBManager(), does not remove the
area used for the visible screen so that area should not be included in the
region passed to the function. xf86InitFBManagerRegion() is useful when non-
contiguous areas are available to be managed, and is required when multiple
framebuffers are stored in video memory (as in the case where an overlay of a
different depth is stored as a second framebuffer in offscreen memory).
13. Colormap Handling
A generic colormap handling layer is provided within the XFree86 common
layer. This layer takes care of most of the details, and only requires a
function from the driver that loads the hardware palette when required. To
use the colormap layer, a driver calls the xf86HandleColormaps() function.
Bool xf86HandleColormaps(ScreenPtr pScreen, int maxColors,
int sigRGBbits, LoadPaletteFuncPtr loadPalette,
SetOverscanFuncPtr setOverscan, unsigned int flags)
This function must be called after the default colormap
has been initialised. The pScrn->gamma field must also
be initialised, preferably by calling xf86SetGamma().
maxColors is the number of entries in the palette.
sigRGBbits is the number of significant bits in each
colour component. This would normally be the same as
pScrn->rgbBits. loadPalette is a driver-provided func-
tion for loading a colormap into the hardware, and is
described below. setOverscan is an optional function
that may be provided when the overscan color is an index
from the standard LUT and when it needs to be adjusted to
keep it as close to black as possible. The setOverscan
function programs the overscan index. It shouldn't nor-
mally be used for depths other than 8. setOverscan
should be set to NULL when it isn't needed. flags may be
set to the following (which may be ORed together):
CMAP_PALETTED_TRUECOLOR
the TrueColor visual is paletted and is just a
special case of DirectColor. This flag is only
valid for bpp > 8.
CMAP_RELOAD_ON_MODE_SWITCH
reload the colormap automatically after mode
switches. This is useful for when the driver
is resetting the hardware during mode switches
and corrupting or erasing the hardware palette.
The colormap layer always reloads the palette after VT
enters so it is not necessary for the driver to save and
restore the palette when switching VTs. The driver must,
however, still save the initial palette during server
start up and restore it during server exit.
void LoadPalette(ScrnInfoPtr pScrn, int numColors, int *indices,
LOCO *colors, VisualPtr pVisual)
LoadPalette() is a driver-provide function for loading a
colormap into hardware. colors is the array of RGB val-
ues that represent the full colormap. indices is a list
of index values into the colors array. These indices
indicate the entries that need to be updated. numColors
is the number of the indices to be updated.
void SetOverscan(ScrnInfoPtr pScrn, int overscan)
SetOverscan() is a driver-provided function for program-
ming the overscan index. As described above, it is nor-
mally only appropriate for LUT modes where all colormap
entries are available for the display, but where one of
them is also used for the overscan (typically 8bpp for
VGA compatible LUTs). It isn't required in cases where
the overscan area is never visible.
14. DPMS Extension
Support code for the DPMS extension is included in the XFree86 common layer.
This code provides an interface between the main extension code, and a means
for drivers to initialise DPMS when they support it. One function is avail-
able to drivers to do this initialisation, and it is always available, even
when the DPMS extension is not supported by the core server (in which case it
returns a failure result).
Bool xf86DPMSInit(ScreenPtr pScreen, DPMSSetProcPtr set, int flags)
This function registers a driver's DPMS level programming
function set. It also checks pScrn->options for the
"dpms" option, and when present marks DPMS as being
enabled for that screen. The set function is called
whenever the DPMS level changes, and is used to program
the requested level. flags is currently not used, and
should be 0. If the initialisation fails for any reason,
including when there is no DPMS support in the core
server, the function returns FALSE.
Drivers that implement DPMS support must provide the following function, that
gets called when the DPMS level is changed:
void ChipDPMSSet(ScrnInfoPtr pScrn, int level, int flags)
Program the DPMS level specified by level. Valid values
of level are DPMSModeOn, DPMSModeStandby, DPMSModeSus-
pend, DPMSModeOff. These values are defined in "exten-
sions/dpms.h".
15. DGA Extension
Drivers can support the XFree86 Direct Graphics Architecture (DGA) by filling
out a structure of function pointers and a list of modes and passing them to
DGAInit.
Bool DGAInit(ScreenPtr pScreen, DGAFunctionPtr funcs,
DGAModePtr modes, int num)
/** The DGAModeRec **/
typedef struct {
int num;
DisplayModePtr mode;
int flags;
int imageWidth;
int imageHeight;
int pixmapWidth;
int pixmapHeight;
int bytesPerScanline;
int byteOrder;
int depth;
int bitsPerPixel;
unsigned long red_mask;
unsigned long green_mask;
unsigned long blue_mask;
int viewportWidth;
int viewportHeight;
int xViewportStep;
int yViewportStep;
int maxViewportX;
int maxViewportY;
int viewportFlags;
int offset;
unsigned char *address;
int reserved1;
int reserved2;
} DGAModeRec, *DGAModePtr;
num
Can be ignored. The DGA DDX will assign these
numbers.
mode
A pointer to the DisplayModeRec for this mode.
flags
The following flags are defined and may be OR'd
together:
DGA_CONCURRENT_ACCESS
Indicates that the driver supports
concurrent graphics accelerator and
linear framebuffer access.
DGA_FILL_RECT
DGA_BLIT_RECT
DGA_BLIT_RECT_TRANS
Indicates that the driver supports
the FillRect, BlitRect or BlitTran-
sRect functions in this mode.
DGA_PIXMAP_AVAILABLE
Indicates that Xlib may be used on
the framebuffer. This flag will usu-
ally be set unless the driver wishes
to prohibit this for some reason.
DGA_INTERLACED
DGA_DOUBLESCAN
Indicates that these are interlaced
or double scan modes.
imageWidth
imageHeight
These are the dimensions of the linear frame-
buffer accessible by the client.
pixmapWidth
pixmapHeight
These are the dimensions of the area of the
framebuffer accessible by the graphics acceler-
ator.
bytesPerScanline
Pitch of the framebuffer in bytes.
byteOrder
Usually the same as pScrn->imageByteOrder.
depth
The depth of the framebuffer in this mode.
bitsPerPixel
The number of bits per pixel in this mode.
red_mask
green_mask
blue_mask
The RGB masks for this mode, if applicable.
viewportWidth
viewportHeight
Dimensions of the visible part of the frame-
buffer. Usually mode->HDisplay and mode->VDis-
play.
xViewportStep
yViewportStep
The granularity of x and y viewport positions
that the driver supports in this mode.
maxViewportX
maxViewportY
The maximum viewport position supported by the
driver in this mode.
viewportFlags
The following may be OR'd together:
DGA_FLIP_IMMEDIATE
The driver supports immediate view-
port changes.
DGA_FLIP_RETRACE
The driver supports viewport changes
at retrace.
offset
The offset into the linear framebuffer that
corresponds to pixel (0,0) for this mode.
/** The DGAFunctionRec **/
typedef struct {
Bool (*OpenFramebuffer)(
ScrnInfoPtr pScrn,
char **name,
unsigned char **mem,
int *size,
int *offset,
int *extra
);
void (*CloseFramebuffer)(ScrnInfoPtr pScrn);
Bool (*SetMode)(ScrnInfoPtr pScrn, DGAModePtr pMode);
void (*SetViewport)(ScrnInfoPtr pScrn, int x, int y, int flags);
int (*GetViewport)(ScrnInfoPtr pScrn);
void (*Flush)(ScrnInfoPtr);
void (*FillRect)(
ScrnInfoPtr pScrn,
int x, int y, int w, int h,
unsigned long color
);
void (*BlitRect)(
ScrnInfoPtr pScrn,
int srcx, int srcy,
int w, int h,
int dstx, int dsty
);
void (*BlitTransRect)(
ScrnInfoPtr pScrn,
int srcx, int srcy,
int w, int h,
int dstx, int dsty,
unsigned long color
);
} DGAFunctionRec, *DGAFunctionPtr;
Bool OpenFramebuffer (pScrn, name, mem, size, offset, extra)
OpenFramebuffer() should pass the client everything it
needs to know to be able to open the framebuffer. These
parameters are OS specific and their meanings are to be
interpreted by an OS specific client library.
name
The name of the device to open or NULL if there
is no special device to open. A NULL name
tells the client that it should open whatever
device one would usually open to access physi-
cal memory.
mem
The physical address of the start of the frame-
buffer.
size
The size of the framebuffer in bytes.
offset
Any offset into the device, if applicable.
flags
Any additional information that the client may
need. Currently, only the DGA_NEED_ROOT flag
is defined.
void CloseFramebuffer (pScrn)
CloseFramebuffer() merely informs the driver (if it even
cares) that client no longer needs to access the frame-
buffer directly. This function is optional.
Bool SetMode (pScrn, pMode)
SetMode() tells the driver to initialize the mode passed
to it. If pMode is NULL, then the driver should restore
the original pre-DGA mode.
void SetViewport (pScrn, x, y, flags)
SetViewport() tells the driver to make the upper left-
hand corner of the visible screen correspond to coordi-
nate (x,y) on the framebuffer. Flags currently defined
are:
DGA_FLIP_IMMEDIATE
The viewport change should occur immediately.
DGA_FLIP_RETRACE
The viewport change should occur at the verti-
cal retrace, but this function should return
sooner if possible.
The (x,y) locations will be passed as the client speci-
fied them, however, the driver is expected to round these
locations down to the next supported location as speci-
fied by the xViewportStep and yViewportStep for the cur-
rent mode.
int GetViewport (pScrn)
GetViewport() gets the current page flip status. Set
bits in the returned int correspond to viewport change
requests still pending. For instance, set bit zero if
the last SetViewport request is still pending, bit one if
the one before that is still pending, etc.
void Flush (pScrn)
This function should ensure that any graphics accelerator
operations have finished. This function should not
return until the graphics accelerator is idle.
void FillRect (pScrn, x, y, w, h, color)
This optional function should fill a rectangle w ? h
located at (x,y) in the given color.
void BlitRect (pScrn, srcx, srcy, w, h, dstx, dsty)
This optional function should copy an area w ? h located
at (srcx,srcy) to location (dstx,dsty). This function
will need to handle copy directions as appropriate.
void BlitTransRect (pScrn, srcx, srcy, w, h, dstx, dsty, color)
This optional function is the same as BlitRect except
that pixels in the source corresponding to the color key
color should be skipped.
16. The XFree86 X Video Extension (Xv) Device Dependent Layer
XFree86 offers the X Video Extension which allows clients to treat video as
any another primitive and ``Put'' video into drawables. By default, the
extension reports no video adaptors as being available since the DDX layer
has not been initialized. The driver can initialize the DDX layer by filling
out one or more XF86VideoAdaptorRecs as described later in this document and
passing a list of XF86VideoAdaptorPtr pointers to the following function:
Bool xf86XVScreenInit(
ScreenPtr pScreen,
XF86VideoAdaptorPtr *adaptPtrs,
int num)
After doing this, the extension will report video adaptors as being avail-
able, providing the data in their respective XF86VideoAdaptorRecs was valid.
xf86XVScreenInit() copies data from the structure passed to it so the driver
may free it after the initialization. At the moment, the DDX only supports
rendering into Window drawables. Pixmap rendering will be supported after a
sufficient survey of suitable hardware is completed.
The XF86VideoAdaptorRec:
typedef struct {
unsigned char type;
int flags;
char *name;
int nEncodings;
XF86VideoEncodingPtr pEncodings;
int nFormats;
XF86VideoFormatPtr pFormats;
int nPorts;
XF86AttributeListPtr pAttributes;
DevUnion *pPortPrivates;
PutVideoFuncPtr PutVideo;
PutStillFuncPtr PutStill;
GetVideoFuncPtr GetVideo;
GetStillFuncPtr GetStill;
StopVideoFuncPtr StopVideo;
SetPortAttributeFuncPtr SetPortAttribute;
GetPortAttributeFuncPtr GetPortAttribute;
QueryBestSizeFuncPtr QueryBestSize;
} XF86VideoAdaptorRec, *XF86VideoAdaptorPtr;
Each adaptor will have its own XF86VideoAdaptorRec. The fields are
as follows:
type
This can be XvInputMask, XvOutputMask or both OR'd
together. This refers to the target drawable and is sim-
ilar to a Window's class. XvInputMask indicates that the
adaptor can put video into a drawable. XvOutputMask
indicates that the adaptor can get video from a drawable.
flags
Currently, the following flags are defined:
VIDEO_NO_CLIPPING
This indicates that the video adaptor does not
support clipping. The driver will never
receive Get/Put requests where less than the
entire area determined by drw_x, drw_y, drw_w
and drw_h is visible.
VIDEO_INVERT_CLIPLIST
This indicates that the video driver requires
the clip list to contain the regions which are
obscured rather than the regions which are are
visible.
VIDEO_EXPOSE
This flag applies to GetStill and GetVideo
only, it indicates the clip list shall contain
obscured regions. Note the source region will
still be clipped against the screen bounds.
This flag is meant for showing all the contents
of the [root] window, if the administrator has
no hesitations regarding security.
name
The name of the adaptor.
nEncodings
pEncodings
The number of encodings the adaptor is capable of and
pointer to the XF86VideoEncodingRec array. The
XF86VideoEncodingRec is described later on.
nFormats
pFormats
The number of formats the adaptor is capable of and
pointer to the XF86VideoFormatRec array. The XF86Video-
FormatRec is described later on.
nPorts
pPortPrivates
The number of ports is the number of separate data
streams which the adaptor can handle simultaneously. If
you have more than one port, the adaptor is expected to
be able to render into more than one window at a time.
pPortPrivates is an array of pointers or ints - one for
each port. A port's private data will be passed to the
driver any time the port is requested to do something
like put the video or stop the video. In the case where
there may be many ports, this enables the driver to know
which port the request is intended for. Most commonly,
this will contain a pointer to the data structure con-
taining information about the port.
pAttributes
There is an array of XF86AttributeListRecs with an entry
for each port.
PutVideo PutStill GetVideo GetStill StopVideo SetPortAttribute Get-
PortAttribute QueryBestSize
These functions define the DDX->driver interface. In
each case, the pointer data is passed to the driver.
This is the port private for that port as described
above. All fields are required except under the follow-
ing conditions:
1. PutVideo and PutStill are not required when the
adaptor type does not contain XvInputMask.
2. GetVideo and GetStill are not required when the
adaptor type does not contain XvOutputMask.
These functions should return Success if the operation
was completed successfully. They can return XvBadAlloc
otherwise. Xv DDX will not call a Get/Put function while
video is active, rather issue a StopVideo call first.
Earlier versions of Xv DDX had a ReclipVideo function,
obsolete now. The clip region will be passed directly by
the functions below. If the VIDEO_NO_CLIPPING flag is
set, the RegionPtr should be ignored by the driver.
ClipBoxes is an X-Y banded region identical to those used
throughout the server. The clipBoxes represent the visi-
ble portions of area determined by drw_x, drw_y, drw_w
and drw_h in the Get/Put function. The boxes are in
screen coordinates, are guaranteed not to overlap and an
empty region will be passed only to GetVideo, once. This
to notify the driver the primitive is totally obscured
now. A StopVideo call will immediately follow neverthe-
less. In the case where the VIDEO_INVERT_CLIPLIST flag
is set, clipBoxes will indicate the areas of the primi-
tive which are obscured rather than the areas visible.
The Region must not be altered by the driver and will be
deleted when the function returns.
typedef int (* PutVideoFuncPtr)( ScrnInfoPtr pScrn,
short vid_x, short vid_y, short drw_x, short drw_y,
short vid_w, short vid_h, short drw_w, short drw_h,
RegionPtr clipBoxes, pointer data )
This indicates that the driver should take a subsection
vid_w ? vid_h at location (vid_x,vid_y) from the video
stream and direct it into the rectangle rw_w ? drw_h at
location (drw_x,drw_y) on the screen, scaling as neces-
sary. Due to the large variations in capabilities of the
various hardware expected to be used with this extension,
it is not expected that all hardware will be able to do
this exactly as described. In that case the driver
should just do ``the best it can,'' scaling as closely to
the target rectangle as it can without rendering outside
of it. In the worst case, the driver can opt to just not
turn on the video.
typedef int (* PutStillFuncPtr)( ScrnInfoPtr pScrn,
short vid_x, short vid_y, short drw_x, short drw_y,
short vid_w, short vid_h, short drw_w, short drw_h,
RegionPtr clipBoxes, pointer data )
This is same as PutVideo except that the driver should
place only one frame from the stream on the screen.
typedef int (* GetVideoFuncPtr)( ScrnInfoPtr pScrn,
short vid_x, short vid_y, short drw_x, short drw_y,
short vid_w, short vid_h, short drw_w, short drw_h,
RegionPtr clipBoxes, pointer data )
This is same as PutVideo except that the driver gets
video from the screen and outputs it. The driver should
do the best it can to get the requested dimensions cor-
rect without reading from an area larger than requested.
typedef int (* GetStillFuncPtr)( ScrnInfoPtr pScrn,
short vid_x, short vid_y, short drw_x, short drw_y,
short vid_w, short vid_h, short drw_w, short drw_h,
RegionPtr clipBoxes, pointer data )
This is the same as GetVideo except that the driver
should place only one frame from the screen into the out-
put stream.
typedef void (* StopVideoFuncPtr)(ScrnInfoPtr pScrn,
pointer data, Bool cleanup)
This indicates the the driver should stop displaying the
video. This is used to stop both input and output video.
The cleanup field indicates that the video is being
stopped because the client requested it to stop or
because the server is exiting the current VT. In that
case the driver should deallocate any offscreen memory
areas (if there are any) being used to put the video to
the screen. If cleanup is not set, the video is being
stopped temporarily due to clipping or moving of the win-
dow, etc... and video will likely be restarted soon so
the driver should not deallocate any offscreen areas
associated with that port.
typedef int (* SetPortAttributeFuncPtr)(ScrnInfoPtr pScrn,
Atom attribute,INT32 value, pointer data)
typedef int (* GetPortAttributeFuncPtr)(ScrnInfoPtr pScrn,
Atom attribute,INT32 *value, pointer data)
A port may have particular attributes such as hue, satu-
ration, brightness or contrast. Xv clients set and get
these attribute values by sending attribute strings
(Atoms) to the server. Such requests end up at these
driver functions. It is recommended that the driver pro-
vide at least the following attributes mentioned in the
Xv client library docs:
XV_ENCODING
XV_HUE
XV_SATURATION
XV_BRIGHTNESS
XV_CONTRAST
but the driver may recognize as many atoms as it wishes.
If a requested attribute is unknown by the driver it
should return BadMatch. XV_ENCODING is the attribute
intended to let the client specify which video encoding
the particular port should be using (see the description
of XF86VideoEncodingRec below). If the requested encod-
ing is unsupported, the driver should return XvBadEncod-
ing. Success should be returned otherwise.
typedef void (* QueryBestSizeFuncPtr)(ScrnInfoPtr pScrn,
Bool motion, short vid_w, short vid_h,
short drw_w, short drw_h,
unsigned int *p_w, unsigned int *p_h, pointer data)
QueryBestSize provides the client with a way to query
what the destination dimensions would end up being if
they were to request that an area vid_w ? vid_h from the
video stream be scaled to rectangle of drw_w ? drw_h on
the screen. Since it is not expected that all hardware
will be able to get the target dimensions exactly, it is
important that the driver provide this function. The
returned dimensions must be less than or equal to the
requested dimension.
The XF86VideoEncodingRec:
typedef struct {
int id;
char *name;
unsigned short width, height;
XvRationalRec rate;
} XF86VideoEncodingRec, *XF86VideoEncodingPtr;
The XF86VideoEncodingRec specifies what encodings the adaptor can
support. Most of this data is just informational and for the
client's benefit, and is what will be reported by XvQueryEncodings.
The id field is expected to be a unique identifier to allow the
client to request a certain encoding via the XV_ENCODING attribute
string.
The XF86VideoFormatRec:
typedef struct {
char depth;
short class;
} XF86VideoFormatRec, *XF86VideoFormatPtr;
This specifies what visuals the video is viewable in. depth is the
depth of the visual (not bpp). class is the visual class such as
TrueColor, DirectColor or PseudoColor. Initialization of an adap-
tor will fail if none of the visuals on that screen are supported.
The XF86AttributeListRec:
typedef struct {
int number;
int *flags;
char **names;
} XF86AttributeListRec, *XF86AttributeListPtr;
Each port will have one of these indicating the number of
attributes for that port, an array of names of the attributes and
an array of flags associated with each attribute. Both arrays are
number in size. Currently defined flags are XvGettable and XvSet-
table which may be OR'd together indicating that attribute is
``gettable'' or ``settable'' by the client. Both arrays can be
nulled if number is zero. While the Xv DDX copies most data from
these structures and stores it internally, including adaptor and
encoding names, the attribute names are not copied, but only their
pointers. Because of this, the strings pointed to by names[] must
exist as long as Xv is initialized.
17. The Loader
This section describes the interfaces to the module loader. The loader
interfaces can be divided into two groups: those that are only available to
the XFree86 common layer, and those that are also available to modules.
17.1 Loader Overview
The loader is capable of loading modules in a range of object formats, and
knowledge of these formats is built in to the loader. Knowledge of new
object formats can be added to the loader in a straightforward manner. This
makes it possible to provide OS-independent modules (for a given CPU archi-
tecture type). In addition to this, the loader can load modules via the OS-
provided dlopen(3) service where available. Such modules are not platform
independent, and the semantics of dlopen() on most systems results in signif-
icant limitations in the use of modules of this type. Support for dlopen()
modules in the loader is primarily for experimental and development purposes.
Symbols exported by the loader (on behalf of the core X server) to modules
are determined at compile time. Only those symbols explicitly exported are
available to modules. All external symbols of loaded modules are exported to
other modules, and to the core X server. The loader can be requested to
check for unresolved symbols at any time, and the action to be taken for
unresolved symbols can be controlled by the caller of the loader. Typically
the caller identifies which symbols can safely remain unresolved and which
cannot.
17.2 Semi-private Loader Interface
The following is the semi-private loader interface that is available to the
XFree86 common layer.
void LoaderInit(void)
The LoaderInit() function initialises the loader, and it
must be called once before calling any other loader func-
tions. This function initialises the tables of exported
symbols, and anything else that might need to be ini-
tialised.
void LoaderSetPath(const char *path)
The LoaderSetPath() function initialises a default module
search path. This must be called if calls to other func-
tions are to be made without explicitly specifying a mod-
ule search path. The search path path must be a string
of one or more comma separated absolute paths. Modules
are expected to be located below these paths, possibly in
subdirectories of these paths.
pointer LoadModule(const char *module, const char *path,
const char **subdirlist, const char **patternlist,
pointer options, const XF86ModReqInfo * modreq,
int *errmaj, int *errmin)
The LoadModule() function loads the module called module.
The return value is a module handle, and may be used in
future calls to the loader that require a reference to a
loaded module. The module name module is normally the
module's canonical name, which doesn't contain any direc-
tory path information, or any object/library file pre-
fixes of suffixes. Currently a full pathname and/or
filename is also accepted. This might change. The other
parameters are:
path
An optional comma-separated list of module
search paths. When NULL, the default search
path is used.
subdirlist
An optional NULL terminated list of subdirecto-
ries to search. When NULL, the default built-
in list is used (refer to stdSubdirs in load-
mod.c). The default list is also substituted
for entries in subdirlist with the value
DEFAULT_LIST. This makes is possible to aug-
ment the default list instead of replacing it.
Subdir elements must be relative, and must not
contain "..". If any violate this requirement,
the load fails.
patternlist
An optional NULL terminated list of POSIX regu-
lar expressions used to connect module file-
names with canonical module names. Each regex
should contain exactly one subexpression that
corresponds to the canonical module name. When
NULL, the default built-in list is used (refer
to stdPatterns in loadmod.c). The default list
is also substituted for entries in patternlist
with the value DEFAULT_LIST. This makes it
possible to augment the default list instead of
replacing it.
options
An optional parameter that is passed to the
newly loaded module's SetupProc function (if it
has one). This argument is normally a NULL
terminated list of Options, and must be inter-
preted that way by modules loaded directly by
the XFree86 common layer. However, it may be
used for application-specific parameter passing
in other situations.
When loading ``external'' modules (modules that
don't have the the standard entry point, for
example a special shared library) the options
parameter can be set to EXTERN_MODULE to tell
the loader not to reject the module when it
doesn't find the standard entry point.
modreq
An optional XF86ModReqInfo* containing ver-
sion/ABI/vendor information to requirements to
check the newly loaded module against. The
main purpose of this is to allow the loader to
verify that a module of the correct type/ver-
sion before running its SetupProc function.
The XF86ModReqInfo struct is defined as fol-
lows:
typedef struct {
CARD8 majorversion; /* MAJOR_UNSPEC */
CARD8 minorversion; /* MINOR_UNSPEC */
CARD16 patchlevel; /* PATCH_UNSPEC */
const char * abiclass; /* ABI_CLASS_NONE */
CARD32 abiversion; /* ABI_VERS_UNSPEC */
const char * moduleclass; /* MOD_CLASS_NONE */
} XF86ModReqInfo;
The information here is compared against the
equivalent information in the module's XF86Mod-
uleVersionInfo record (which is described
below). The values in comments above indicate
``don't care'' settings for each of the fields.
The comparisons made are as follows:
majorversion
Must match the module's majorversion
exactly.
minorversion
The module's minor version must be no
less than this value. This compari-
son is only made if majorversion is
specified and matches.
patchlevel
The module's patchlevel must be no
less than this value. This compari-
son is only made if minorversion is
specified and matches.
abiclass
String must match the module's abi-
class string.
abiversion
Must be consistent with the module's
abiversion (major equal, minor no
older).
moduleclass
String must match the module's mod-
uleclass string.
errmaj
An optional pointer to a variable holding the
major part or the error code. When provided,
it *errmaj is filled in when LoadModule()
fails.
errmin
Like errmaj, but for the minor part of the
error code.
void UnloadModule(pointer mod)
This function unloads the module referred to by the han-
dle mod. All child modules are also unloaded recur-
sively. This function must not be used to directly
unload modules that are child modules (i.e., those that
have been loaded with LoadSubModule()).
17.3 Module Requirements
Modules must provide information about themselves to the loader, and may
optionally provide entry points for "setup" and "teardown" functions (those
two functions are referred to here as SetupProc and TearDownProc).
The module information is contained in the XF86ModuleVersionInfo struct,
which is defined as follows:
typedef struct {
const char * modname; /* name of module, e.g. "foo" */
const char * vendor; /* vendor specific string */
CARD32 _modinfo1_; /* constant MODINFOSTRING1/2 to find */
CARD32 _modinfo2_; /* infoarea with a binary editor/sign tool */
CARD32 xf86version; /* contains XF86_VERSION_CURRENT */
CARD8 majorversion; /* module-specific major version */
CARD8 minorversion; /* module-specific minor version */
CARD16 patchlevel; /* module-specific patch level */
const char * abiclass; /* ABI class that the module uses */
CARD32 abiversion; /* ABI version */
const char * moduleclass; /* module class */
CARD32 checksum[4]; /* contains a digital signature of the */
/* version info structure */
} XF86ModuleVersionInfo;
The fields are used as follows:
modname
The module's name. This field is currently only for
informational purposes, but the loader may be modified in
future to require it to match the module's canonical
name.
vendor
The module vendor. This field is for informational pur-
poses only.
_modinfo1_
This field holds the first part of a signature that can
be used to locate this structure in the binary. It
should always be initialised to MODINFOSTRING1.
_modinfo2_
This field holds the second part of a signature that can
be used to locate this structure in the binary. It
should always be initialised to MODINFOSTRING2.
xf86version
The XFree86 version against which the module was com-
piled. This is mostly for informational/diagnostic pur-
poses. It should be initialised to XF86_VERSION_CURRENT,
which is defined in xf86Version.h.
majorversion
The module-specific major version. For modules where
this version is used for more than simply informational
purposes, the major version should only change (be incre-
mented) when ABI incompatibilities are introduced, or ABI
components are removed.
minorversion
The module-specific minor version. For modules where
this version is used for more than simply informational
purposes, the minor version should only change (be incre-
mented) when ABI additions are made in a backward compat-
ible way. It should be reset to zero when the major ver-
sion is increased.
patchlevel
The module-specific patch level. The patch level should
increase with new revisions of the module where there are
no ABI changes, and it should be reset to zero when the
minor version is increased.
abiclass
The ABI class that the module requires. The class is
specified as a string for easy extensibility. It should
indicate which (if any) of the X server's built-in ABI
classes that the module relies on, or a third-party ABI
if appropriate. Built-in ABI classes currently defined
are:
ABI_CLASS_NONE
no class
ABI_CLASS_ANSIC
only requires the ANSI C interfaces
ABI_CLASS_VIDEODRV
requires the video driver ABI
ABI_CLASS_XINPUT
requires the XInput driver ABI
ABI_CLASS_EXTENSION
requires the extension module ABI
ABI_CLASS_FONT
requires the font module ABI
abiversion
The version of abiclass that the module requires. The
version consists of major and minor components. The
major version must match and the minor version must be no
newer than that provided by the server or parent module.
Version identifiers for the built-in classes currently
defined are:
ABI_ANSIC_VERSION
ABI_VIDEODRV_VERSION
ABI_XINPUT_VERSION
ABI_EXTENSION_VERSION
ABI_FONT_VERSION
moduleclass
This is similar to the abiclass field, except that it
defines the type of module rather than the ABI it
requires. For example, although all video drivers
require the video driver ABI, not all modules that
require the video driver ABI are video drivers. This
distinction can be made with the moduleclass. Currently
pre-defined module classes are:
MOD_CLASS_NONE
MOD_CLASS_VIDEODRV
MOD_CLASS_XINPUT
MOD_CLASS_FONT
MOD_CLASS_EXTENSION
checksum
Not currently used.
The module version information, and the optional SetupProc and TearDownProc
entry points are found by the loader by locating a data object in the module
called "modnameModuleData", where "modname" is the canonical name of the mod-
ule. Modules must contain such a data object, and it must be declared with
global scope, be compile-time initialised, and is of the following type:
typedef struct {
XF86ModuleVersionInfo * vers;
ModuleSetupProc setup;
ModuleTearDownProc teardown;
} XF86ModuleData;
The vers parameter must be initialised to a pointer to a correctly ini-
tialised XF86ModuleVersionInfo struct. The other two parameter are optional,
and should be initialised to NULL when not required. The other parameters
are defined as
typedef pointer (*ModuleSetupProc)(pointer, pointer, int *, int *)
typedef void (*ModuleTearDownProc)(pointer)
pointer SetupProc(pointer module, pointer options,
int *errmaj, int *errmin)
When defined, this function is called by the loader after
successfully loading a module. module is a handle for
the newly loaded module, and maybe used by the SetupProc
if it calls other loader functions that require a refer-
ence to it. The remaining arguments are those that were
passed to the LoadModule() (or LoadSubModule()), and are
described above. When the SetupProc is successful it
must return a non-NULL value. The loader checks this,
and if it is NULL it unloads the module and reports the
failure to the caller of LoadModule(). If the SetupProc
does things that need to be undone when the module is
unloaded, it should define a TearDownProc, and return a
pointer that the TearDownProc can use to undo what has
been done.
When a module is loaded multiple times, the SetupProc is
called once for each time it is loaded.
void TearDownProc(pointer tearDownData)
When defined, this function is called when the loader
unloads a module. The tearDownData parameter is the
return value of the SetupProc() that was called when the
module was loaded. The purpose of this function is to
clean up before the module is unloaded (for example, by
freeing allocated resources).
17.4 Public Loader Interface
The following is the Loader interface that is available to any part of the
server, and may also be used from within modules.
pointer LoadSubModule(pointer parent, const char *module,
const char **subdirlist, const char **patternlist,
pointer options, const XF86ModReqInfo * modreq,
int *errmaj, int *errmin)
This function is like the LoadModule() function described
above, except that the module loaded is registered as a
child of the calling module. The parent parameter is the
calling module's handle. Modules loaded with this func-
tion are automatically unloaded when the parent module is
unloaded. The other difference is that the path parame-
ter may not be specified. The module search path used
for modules loaded with this function is the default
search path as initialised with LoaderSetPath().
void UnloadSubModule(pointer module)
This function unloads the module with handle module. If
that module itself has children, they are also unloaded.
It is like LoadModule(), except that it is safe to use
for unloading child modules.
pointer LoaderSymbol(const char *symbol)
This function returns the address of the symbol with name
symbol. This may be used to locate a module entry point
with a known name.
char **LoaderlistDirs(const char **subdirlist,
const char **patternlist)
This function returns a NULL terminated list of canonical
modules names for modules found in the default module
search path. The subdirlist and patternlist parameters
are as described above, and can be used to control the
locations and names that are searched. If no modules are
found, the return value is NULL. The returned list
should be freed by calling LoaderFreeDirList() when it is
no longer needed.
void LoaderFreeDirList(char **list)
This function frees a module list created by Loaderlist-
Dirs().
void LoaderReqSymLists(const char **list0, ...)
This function allows the registration of required symbols
with the loader. It is normally used by a caller of
LoadSubModule(). If any symbols registered in this way
are found to be unresolved when LoaderCheckUnresolved()
is called then LoaderCheckUnresolved() will report a
failure. The function takes one or more NULL terminated
lists of symbols. The end of the argument list is indi-
cated by a NULL argument.
void LoaderReqSymbols(const char *sym0, ...)
This function is like LoaderReqSymLists() except that its
arguments are symbols rather than lists of symbols. This
function is more convenient when single functions are to
be registered, especially when the single function might
depend on runtime factors. The end of the argument list
is indicated by a NULL argument.
void LoaderRefSymLists(const char **list0, ...)
This function allows the registration of possibly unre-
solved symbols with the loader. When LoaderCheckUnre-
solved() is run it won't generate warnings for symbols
registered in this way unless they were also registered
as required symbols.
void LoaderRefSymbols(const char *sym0, ...)
This function is like LoaderRefSymLists() except that its
arguments are symbols rather than lists of symbols. This
function is more convenient when single functions are to
be registered, especially when the single function might
depend on runtime factors. The end of the argument list
is indicated by a NULL argument.
int LoaderCheckUnresolved(int delayflag)
This function checks for unresolved symbols. It gener-
ates warnings for unresolved symbols that have not been
registered with LoaderRefSymLists(), and maps them to a
dummy function. This behaviour may change in future. If
unresolved symbols are found that have been registered
with LoaderReqSymLists() or LoaderReqSymbols() then this
function returns a non-zero value. If none of these sym-
bols are unresolved the return value is zero, indicating
success.
The delayflag parameter should normally be set to
LD_RESOLV_IFDONE.
LoaderErrorMsg(const char *name, const char *modname,
int errmaj, int errmin)
This function prints an error message that includes the
text ``Failed to load module'', the module name modname,
a message specific to the errmaj value, and the value if
errmin. If name is non-NULL, it is printed as an identi-
fying prefix to the message (followed by a `:').
17.5 Special Registration Functions
The loader contains some functions for registering some classes of modules.
These may be moved out of the loader at some point.
void LoadExtension(ExtensionModule *ext)
This registers the entry points for the extension identi-
fied by ext. The ExtensionModule struct is defined as:
typedef struct {
InitExtension initFunc;
char * name;
Bool *disablePtr;
InitExtension setupFunc;
} ExtensionModule;
void LoadFont(FontModule *font)
This registers the entry points for the font rasteriser
module identified by font. The FontModule struct is
defined as:
typedef struct {
InitFont initFunc;
char * name;
pointer module;
} FontModule;
18. Helper Functions
This section describe ``helper'' functions that video driver might find use-
ful. While video drivers are not required to use any of these to be consid-
ered ``compliant'', the use of appropriate helpers is strongly encouraged to
improve the consistency of driver behaviour.
18.1 Functions for printing messages
ErrorF(const char *format, ...)
This is the basic function for writing to the error log
(typically stderr and/or a log file). Video drivers
should usually avoid using this directly in favour of the
more specialised functions described below. This func-
tion is useful for printing messages while debugging a
driver.
FatalError(const char *format, ...)
This prints a message and causes the Xserver to abort.
It should rarely be used within a video driver, as most
error conditions should be flagged by the return values
of the driver functions. This allows the higher layers
to decide how to proceed. In rare cases, this can be
used within a driver if a fatal unexpected condition is
found.
xf86ErrorF(const char *format, ...)
This is like ErrorF(), except that the message is only
printed when the Xserver's verbosity level is set to the
default (1) or higher. It means that the messages are
not printed when the server is started with the -quiet
flag. Typically this function would only be used for
continuing messages started with one of the more spe-
cialised functions described below.
xf86ErrorFVerb(int verb, const char *format, ...)
Like xf86ErrorF(), except the minimum verbosity level for
which the message is to be printed is given explicitly.
Passing a verb value of zero means the message is always
printed. A value higher than 1 can be used for informa-
tion would normally not be needed, but which might be
useful when diagnosing problems.
xf86Msg(MessageType type, const char *format, ...)
This is like xf86ErrorF(), except that the message is
prefixed with a marker determined by the value of type.
The marker is used to indicate the type of message (warn-
ing, error, probed value, config value, etc). Note the
xf86Verbose value is ignored for messages of type
X_ERROR.
The marker values are:
X_PROBED
Value was probed.
X_CONFIG
Value was given in the config file.
X_DEFAULT
Value is a default.
X_CMDLINE
Value was given on the command line.
X_NOTICE
Notice.
X_ERROR
Error message.
X_WARNING
Warning message.
X_INFO
Informational message.
X_NONE
No prefix.
xf86MsgVerb(MessageType type, int verb, const char *format, ...)
Like xf86Msg(), but with the verbosity level given
explicitly.
xf86DrvMsg(int scrnIndex, MessageType type, const char *format,
...)
This is like xf86Msg() except that the driver's name (the
name field of the ScrnInfoRec) followed by the scrnIndex
in parentheses is printed following the prefix. This
should be used by video drivers in most cases as it
clearly indicates which driver/screen the message is for.
If scrnIndex is negative, this function behaves exactly
like xf86Msg().
NOTE: This function can only be used after the ScrnIn-
foRec and its name field have been allocated. That means
that it can not be used before the END of the ChipProbe()
function. Prior to that, use xf86Msg(), providing the
driver's name explicitly. No screen number can be sup-
plied at that point.
xf86DrvMsgVerb(int scrnIndex, MessageType type, int verb,
const char *format, ...)
Like xf86DrvMsg(), but with the verbosity level given
explicitly.
18.2 Functions for setting values based on command line and config file
Bool xf86SetDepthBpp(ScrnInfoPtr scrp, int depth, int bpp, int
fbbpp,
int depth24flags)
This function sets the depth, pixmapBPP and bitsPerPixel
fields of the ScrnInfoRec. It also determines the
defaults for display-wide attributes and pixmap formats
the screen will support, and finds the Display subsection
that matches the depth/bpp. This function should nor-
mally be called very early from the ChipPreInit() func-
tion.
It requires that the confScreen field of the ScrnInfoRec
be initialised prior to calling it. This is done by the
XFree86 common layer prior to calling ChipPreInit().
The parameters passed are:
depth
driver's preferred default depth if no other is
given. If zero, use the overall server
default.
bpp
Same, but for the pixmap bpp.
fbbpp
Same, but for the framebuffer bpp.
depth24flags
Flags that indicate the level of 24/32bpp sup-
port and whether conversion between different
framebuffer and pixmap formats is supported.
The flags for this argument are defined as fol-
lows, and multiple flags may be ORed together:
NoDepth24Support
No depth 24 formats supported
Support24bppFb
24bpp framebuffer supported
Support32bppFb
32bpp framebuffer supported
SupportConvert24to32
Can convert 24bpp pixmap to 32bpp fb
SupportConvert32to24
Can convert 32bpp pixmap to 24bpp fb
ForceConvert24to32
Force 24bpp pixmap to 32bpp fb con-
version
ForceConvert32to24
Force 32bpp pixmap to 24bpp fb con-
version
It uses the command line, config file, and default values
in the correct order of precedence to determine the depth
and bpp values. It is up to the driver to check the
results to see that it supports them. If not the Chip-
PreInit() function should return FALSE.
If only one of depth/bpp is given, the other is set to a
reasonable (and consistent) default.
If a driver finds that the initial depth24flags it uses
later results in a fb format that requires more video
memory than is available it may call this function a sec-
ond time with a different depth24flags setting.
On success, the return value is TRUE. On failure it
prints an error message and returns FALSE.
The following fields of the ScrnInfoRec are initialised
by this function:
depth, bitsPerPixel, display, imageByteOrder,
bitmapScanlinePad, bitmapScanlineUnit, bitmap-
BitOrder, numFormats, formats, fbFormat.
void xf86PrintDepthBpp(scrnInfoPtr scrp)
This function can be used to print out the depth and bpp
settings. It should be called after the final call to
xf86SetDepthBpp().
Bool xf86SetWeight(ScrnInfoPtr scrp, rgb weight, rgb mask)
This function sets the weight, mask, offset and rgbBits
fields of the ScrnInfoRec. It would normally be called
fairly early in the ChipPreInit() function for
depths > 8bpp.
It requires that the depth and display fields of the
ScrnInfoRec be initialised prior to calling it.
The parameters passed are:
weight
driver's preferred default weight if no other
is given. If zero, use the overall server
default.
mask
Same, but for mask.
It uses the command line, config file, and default values
in the correct order of precedence to determine the
weight value. It derives the mask and offset values from
the weight and the defaults. It is up to the driver to
check the results to see that it supports them. If not
the ChipPreInit() function should return FALSE.
On success, this function prints a message showing the
weight values selected, and returns TRUE.
On failure it prints an error message and returns FALSE.
The following fields of the ScrnInfoRec are initialised
by this function:
weight, mask, offset.
Bool xf86SetDefaultVisual(ScrnInfoPtr scrp, int visual)
This function sets the defaultVisual field of the ScrnIn-
foRec. It would normally be called fairly early from the
ChipPreInit() function.
It requires that the depth and display fields of the
ScrnInfoRec be initialised prior to calling it.
The parameters passed are:
visual
driver's preferred default visual if no other
is given. If -1, use the overall server
default.
It uses the command line, config file, and default values
in the correct order of precedence to determine the
default visual value. It is up to the driver to check
the result to see that it supports it. If not the Chip-
PreInit() function should return FALSE.
On success, this function prints a message showing the
default visual selected, and returns TRUE.
On failure it prints an error message and returns FALSE.
Bool xf86SetGamma(ScrnInfoPtr scrp, Gamma gamma)
This function sets the gamma field of the ScrnInfoRec.
It would normally be called fairly early from the Chip-
PreInit() function in cases where the driver supports
gamma correction.
It requires that the monitor field of the ScrnInfoRec be
initialised prior to calling it.
The parameters passed are:
gamma
driver's preferred default gamma if no other is
given. If zero (< 0.01), use the overall
server default.
It uses the command line, config file, and default values
in the correct order of precedence to determine the gamma
value. It is up to the driver to check the results to
see that it supports them. If not the ChipPreInit()
function should return FALSE.
On success, this function prints a message showing the
gamma value selected, and returns TRUE.
On failure it prints an error message and returns FALSE.
void xf86SetDpi(ScrnInfoPtr pScrn, int x, int y)
This function sets the xDpi and yDpi fields of the Scrn-
InfoRec. The driver can specify preferred defaults by
setting x and y to non-zero values. The -dpi command
line option overrides all other settings. Otherwise, if
the DisplaySize entry is present in the screen's Monitor
config file section, it is used together with the virtual
size to calculate the dpi values. This function should
be called after all the mode resolution has been done.
void xf86SetBlackWhitePixels(ScrnInfoPtr pScrn)
This functions sets the blackPixel and whitePixel fields
of the ScrnInfoRec according to whether or not the -flip-
Pixels command line options is present.
const char *xf86GetVisualName(int visual)
Returns a printable string with the visual name matching
the numerical visual class provided. If the value is
outside the range of valid visual classes, NULL is
returned.
18.3 Primary Mode functions
The primary mode helper functions are those which would normally be used by a
driver, unless it has unusual requirements which cannot be catered for the by
the helpers.
int xf86ValidateModes(ScrnInfoPtr scrp, DisplayModePtr availModes,
char **modeNames, ClockRangePtr clockRanges,
int *linePitches, int minPitch, int maxPitch,
int pitchInc, int minHeight, int maxHeight,
int virtualX, int virtualY,
unsigned long apertureSize,
LookupModeFlags strategy)
This function basically selects the set of modes to use
based on those available and the various constraints. It
also sets some other related parameters. It is normally
called near the end of the ChipPreInit() function.
The parameters passed to the function are:
availModes
List of modes available for the monitor.
modeNames
List of mode names that the screen is request-
ing.
clockRanges
A list of clock ranges allowed by the driver.
Each range includes whether interlaced or mul-
tiscan modes are supported for that range. See
below for more on clockRanges.
linePitches
List of supported line pitches supported by the
driver. This is optional and should be NULL
when not used.
minPitch
Minimum line pitch supported by the driver.
This must be supplied when linePitches is NULL,
and is ignored otherwise.
maxPitch
Maximum line pitch supported by the driver.
This is required when minPitch is required.
pitchInc
Granularity of horizontal pitch values as sup-
ported by the chipset. This is expressed in
bits. This must be supplied.
minHeight
minimum virtual height allowed. If zero, no
limit is imposed.
maxHeight
maximum virtual height allowed. If zero, no
limit is imposed.
virtualX
If greater than zero, this is the virtual width
value that will be used. Otherwise, the vir-
tual width is chosen to be the smallest that
can accommodate the modes selected.
virtualY
If greater than zero, this is the virtual
height value that will be used. Otherwise, the
virtual height is chosen to be the smallest
that can accommodate the modes selected.
apertureSize
The size (in bytes) of the aperture used to
access video memory.
strategy
The strategy to use when choosing from multiple
modes with the same name. The options are:
LOOKUP_DEFAULT
???
LOOKUP_BEST_REFRESH
mode with best refresh rate
LOOKUP_CLOSEST_CLOCK
mode with closest matching clock
LOOKUP_LIST_ORDER
first usable mode in list
LOOKUP_CLKDIV2
Allow halved clocks
LOOKUP_CLKDIV2 can be combined (OR'ed) with one
of the others.
This function requires that the following fields of the
ScrnInfoRec are initialised prior to calling it:
clock[]
List of discrete clocks (when non-pro-
grammable).
numClocks
Number of discrete clocks (when non-pro-
grammable).
progClock
Whether the clock is programmable or not.
formats
pixmap formats for screen
numFormats
number of pixmap formats for screen
videoRam
total video memory size (in bytes)
maxHValue
Maximum horizontal timing value allowed
maxVValue
Maximum vertical timing value allowed
This function fills in the following ScrnInfoRec fields:
modePool
A subset of the modes available to the monitor
which are compatible with the driver.
modes
One mode entry for each of the requested modes,
with the status field of each filled in to
indicate if the mode has been accepted or not.
This list of modes is a circular list.
virtualX
The resulting virtual width.
virtualY
The resulting virtual height.
displayWidth
The resulting line pitch.
virtualFrom
Where the virtual size was determined from.
The first stage of this function checks that the virtualX
and virtualY values supplied (if greater than zero) are
consistent with the line pitch and maxHeight limitations.
If not, an error message is printed, and the return value
is -1.
The second stage sets up the mode pool, eliminating imme-
diately any modes that exceed the driver's line pitch
limits, and also the virtual width and height limits (if
greater than zero). For each mode removed an informa-
tional message is printed at verbosity level 2. If the
mode pool ends up being empty, an error message is
printed, and the return value is -1.
The final stage is to lookup each mode, and fill in the
remaining parameters. If an error condition is encoun-
tered, a message is printed, and the return value is -1.
Otherwise, the return value is the number of valid modes
found (0 if none are found).
A message is only printed by this function when a funda-
mental problem is found. It is intended that this func-
tion may be called more than once if there is more than
one set of constraints that the driver can work within.
If this function returns -1, the ChipPreInit() function
should return FALSE.
clockRanges is a linked list of clock ranges allowed by
the driver. If a mode doesn't fit in any of the defined
clockRanges, it is rejected. The first clockRange that
matches all requirements is used.
clockRanges contains the following fields:
minClock
maxClock
The lower and upper mode clock bounds for which
the rest of the clockRange parameters apply.
Since these are the mode clocks, they are not
scaled with the ClockMulFactor and ClockDivFac-
tor. It is up to the driver to adjust these
values if they depend on the clock scaling fac-
tors.
clockIndex
(not used yet) -1 for programmable clocks
interlaceAllowed
TRUE if interlacing is allowed for this range
doubleScanAllowed
TRUE if doublescan is allowed for this range
ClockMulFactor
ClockDivFactor
Scaling factors that are applied to the mode
clocks ONLY before selecting a clock index
(when there is no programmable clock) or a Syn-
thClock value. This is useful for drivers that
support pixel multiplexing or that need to
scale the clocks because of hardware restric-
tions (like sending 24bpp data to an 8 bit RAM-
DAC using a tripled clock).
Note that these parameters describe what must
be done to the mode clock to achieve the data
transport clock between graphics controller and
RAMDAC. For example for 2:1 pixel multiplex-
ing, two pixels are sent to the RAMDAC on each
clock. This allows the RAMDAC clock to be half
of the actual pixel clock. Hence, ClockMulFac-
tor=1 and ClockDivFactor=2. This means that
the clock used for clock selection (ie, deter-
mining the correct clock index from the list of
discrete clocks) or for the SynthClock field in
case of a programmable clock is: (mode->Clock
* ClockMulFactor) / ClockDivFactor.
PrivFlags
This field is copied into the mode->PrivFlags
field when this clockRange is selected by
xf86ValidateModes(). It allows the driver to
find out what clock range was selected, so it
knows it needs to set up pixel multiplexing or
any other range-dependent feature. This field
is purely driver-defined: it may contain flag
bits, an index or anything else (as long as it
is an INT).
Note that the mode->SynthClock field is always filled in
by xf86ValidateModes(): it will contain the ``data trans-
port clock'', which is the clock that will have to be
programmed in the chip when it has a programmable clock,
or the clock that will be picked from the clocks list
when it is not a programmable one. Thus:
mode->SynthClock =
(mode->Clock * ClockMulFactor) / ClockDivFactor
void xf86PruneDriverModes(ScrnInfoPtr scrp)
This function deletes modes in the modes field of the
ScrnInfoRec that have been marked as invalid. This is
normally run after having run xf86ValidateModes() for the
last time. For each mode that is deleted, a warning mes-
sage is printed out indicating the reason for it being
deleted.
void xf86SetCrtcForModes(ScrnInfoPtr scrp, int adjustFlags)
This function fills in the Crtc* fields for all the modes
in the modes field of the ScrnInfoRec. The adjustFlags
parameter determines how the vertical CRTC values are
scaled for interlaced modes. They are halved if it is
INTERLACE_HALVE_V. The vertical CRTC values are doubled
for doublescan modes, and are further multiplied by the
VScan value.
This function is normally called after calling
xf86PruneDriverModes().
NOTE: The Crtc* fields are not initialised anywhere else,
so the driver must either call this function or ini-
tialise them itself.
void xf86PrintModes(ScrnInfoPtr scrp)
This function prints out the virtual size setting, and
the line pitch being used. It also prints out one line
for each mode being used, including its pixel clock, hor-
izontal sync rate, refresh rate, and whether it is inter-
laced or multiscan.
This function is normally called after calling
xf86SetCrtcForModes().
18.4 Secondary Mode functions
The secondary mode helper functions are functions which are normally used by
the primary mode helper functions, and which are not normally called directly
by a driver. If a driver has unusual requirements and needs to do its own
mode validation, it might be able to make use of some of these secondary mode
helper functions.
int xf86GetNearestClock(ScrnInfoPtr scrp, int freq, Bool allowDiv2,
int *divider)
This function returns the index of the closest clock to
the frequency freq given (in kHz). It assumes that the
number of clocks is greater than zero. It requires that
the numClocks and clock fields of the ScrnInfoRec are
initialised. The allowDiv2 field determines if the
clocks can be halved. The *divider return value indi-
cates whether clock division is used when determining the
clock returned.
This function is only for non-programmable clocks.
const char *xf86ModeStatusToString(ModeStatus status)
This function converts the status value to a descriptive
printable string.
ModeStatus xf86LookupMode(ScrnInfoPtr scrp, DisplayModePtr modep,
ClockRangePtr clockRanges, LookupModeFlags strategy)
This function takes a pointer to a mode with the name
filled in, and looks for a mode in the modePool list
which matches. The parameters of the matching mode are
filled in to *modep. The clockRanges and strategy param-
eters are as for the xf86ValidateModes() function above.
This function requires the modePool, clock[], numClocks
and progClock fields of the ScrnInfoRec to be initialised
before being called.
The return value is MODE_OK if a mode was found. Other-
wise it indicates why a matching mode could not be found.
ModeStatus xf86InitialCheckModeForDriver(ScrnInfoPtr scrp,
DisplayModePtr mode, int maxPitch,
int virtualX, int virtualY)
This function checks the passed mode against some basic
driver constraints. Apart from the ones passed explic-
itly, the maxHValue and maxVValue fields of the ScrnIn-
foRec are also used. If the ValidMode field of the Scrn-
InfoRec is set, that function is also called to check the
mode.
If the mode is consistent with the constraints, the
return value is MODE_OK. Otherwise the return value
indicates which constraint wasn't met.
void xf86DeleteMode(DisplayModePtr *modeList, DisplayModePtr mode)
This function deletes the mode given from the modeList.
It never prints any messages, so it is up to the caller
to print a message if required.
18.5 Functions for handling strings and tokens
Tables associating strings and numerical tokens combined with the following
functions provide a compact way of handling strings from the config file, and
for converting tokens into printable strings. The table data structure is:
typedef struct {
int token;
const char * name;
} SymTabRec, *SymTabPtr;
A table is an initialised array of SymTabRec. The tokens must be non-nega-
tive integers. Multiple names may be mapped to a single token. The table is
terminated with an element with a token value of -1 and NULL for the name.
const char *xf86TokenToString(SymTabPtr table, int token)
This function returns the first string in table that
matches token. If no match is found, NULL is returned
(NOTE, older versions of this function would return the
string "unknown" when no match is found).
int xf86StringToToken(SymTabPtr table, const char *string)
This function returns the first token in table that
matches string. The xf86NameCmp() function is used to
determine the match. If no match is found, -1 is
returned.
18.6 Functions for finding which config file entries to use
These functions can be used to select the appropriate config file entries
that match the detected hardware. They are described above in the Probe
(section 5.8, page 1) and Available Functions (section 9.3, page 1) sections.
18.7 Probing discrete clocks on old hardware
The xf86GetClocks() function may be used to assist in finding the discrete
pixel clock values on older hardware.
void xf86GetClocks(ScrnInfoPtr pScrn, int num,
Bool (*ClockFunc)(ScrnInfoPtr, int),
void (*ProtectRegs)(ScrnInfoPtr, Bool),
void (*BlankScreen)(ScrnInfoPtr, Bool),
int vertsyncreg, int maskval, int knownclkindex,
int knownclkvalue)
This function uses a comparative sampling method to mea-
sure the discrete pixel clock values. The number of dis-
crete clocks to measure is given by num. clockFunc is a
function that selects the n'th clock. It should also
save or restore any state affected by programming the
clocks when the index passed is CLK_REG_SAVE or
CLK_REG_RESTORE. ProtectRegs is a function that does
whatever is required to protect the hardware state while
selecting a new clock. BlankScreen is a function that
blanks the screen. vertsyncreg and maskval are the reg-
ister and bitmask to check for the presence of vertical
sync pulses. knownclkindex and knownclkvalue are the
index and value of a known clock. These are the known
references on which the comparative measurements are
based. The number of clocks probed is set in pScrn->num-
Clocks, and the probed clocks are set in the
pScrn->clock[] array. All of the clock values are in
units of kHz.
void xf86ShowClocks(ScrnInfoPtr scrp, MessageType from)
Print out the pixel clocks scrp->clock[]. from indicates
whether the clocks were probed or from the config file.
19. The vgahw module
The vgahw modules provides an interface for saving, restoring and programming
the standard VGA registers, and for handling VGA colourmaps.
19.1 Data Structures
The public data structures used by the vgahw module are vgaRegRec and vgaH-
WRec. They are defined in vgaHW.h.
19.2 General vgahw Functions
Bool vgaHWGetHWRec(ScrnInfoPtr pScrn)
This function allocates a vgaHWRec structure, and hooks
it into the ScrnInfoRec's privates. Like all information
hooked into the privates, it is persistent, and only
needs to be allocated once per screen. This function
should normally be called from the driver's ChipPreInit()
function. The vgaHWRec is zero-allocated, and the fol-
lowing fields are explicitly initialised:
ModeReg.DAC[]
initialised with a default colourmap
ModeReg.Attribute[0x11]
initialised with the default overscan index
ShowOverscan
initialised according to the "ShowOverscan"
option
paletteEnabled
initialised to FALSE
cmapSaved
initialised to FALSE
pScrn
initialised to pScrn
In addition to the above, vgaHWSetStdFuncs() is called to
initialise the register access function fields with the
standard VGA set of functions.
Once allocated, a pointer to the vgaHWRec can be obtained
from the ScrnInfoPtr with the VGAHWPTR(pScrn) macro.
void vgaHWFreeHWRec(ScrnInfoPtr pScrn)
This function frees a vgaHWRec structure. It should be
called from a driver's ChipFreeScreen() function.
Bool vgaHWSetRegCounts(ScrnInfoPtr pScrn, int numCRTC,
int numSequencer, int numGraphics, int numAttribute)
This function allows the number of CRTC, Sequencer,
Graphics and Attribute registers to be changed. This
makes it possible for extended registers to be saved and
restored with vgaHWSave() and vgaHWRestore(). This func-
tion should be called after a vgaHWRec has been allocated
with vgaHWGetHWRec(). The default values are defined in
vgaHW.h as follows:
#define VGA_NUM_CRTC 25
#define VGA_NUM_SEQ 5
#define VGA_NUM_GFX 9
#define VGA_NUM_ATTR 21
Bool vgaHWCopyReg(vgaRegPtr dst, vgaRegPtr src)
This function copies the contents of the VGA saved regis-
ters in src to dst. Note that it isn't possible to sim-
ply do this with memcpy() (or similar). This function
returns TRUE unless there is a problem allocating space
for the CRTC and related fields in dst.
void vgaHWSetStdFuncs(vgaHWPtr hwp)
This function initialises the register access function
fields of hwp with the standard VGA set of functions.
This is called by vgaHWGetHWRec(), so there is usually no
need to call this explicitly. The register access func-
tions are described below.
void vgaHWSetMmioFuncs(vgaHWPtr hwp, CARD8 *base, int offset)
This function initialised the register access function
fields of hwp with a generic MMIO set of functions.
hwp->MMIOBase is initialised with base, which must be the
virtual address that the start of MMIO area is mapped to.
hwp->MMIOOffset is initialised with offset, which must be
calculated in such a way that when the standard VGA I/O
port value is added to it the correct offset into the
MMIO area results. That means that these functions are
only suitable when the VGA I/O ports are made available
in a direct mapping to the MMIO space. If that is not
the case, the driver will need to provide its own regis-
ter access functions. The register access functions are
described below.
Bool vgaHWMapMem(ScrnInfoPtr pScrn)
This function maps the VGA memory window. It requires
that the vgaHWRec be allocated. If a driver requires
non-default MapPhys or MapSize settings (the physical
location and size of the VGA memory window) then those
fields of the vgaHWRec must be initialised before calling
this function. Otherwise, this function initialiases the
default values of 0xA0000 for MapPhys and (64 * 1024) for
MapSize. This function must be called before attempting
to save or restore the VGA state. If the driver doesn't
call it explicitly, the vgaHWSave() and vgaHWRestore()
functions may call it if they need to access the VGA mem-
ory (in which case they will also call vgaHWUnmapMem() to
unmap the VGA memory before exiting).
void vgaHWUnmapMem(ScrnInfoPtr pScrn)
This function unmaps the VGA memory window. It must only
be called after the memory has been mapped. The Base
field of the vgaHWRec field is set to NULL to indicate
that the memory is no longer mapped.
void vgaHWGetIOBase(vgaHWPtr hwp)
This function initialises the IOBase field of the vgaH-
WRec. This function must be called before using any
other functions that access the video hardware.
A macro VGAHW_GET_IOBASE() is also available in vgaHW.h
that returns the I/O base, and this may be used when the
vgahw module is not loaded (for example, in the Chip-
Probe() function).
void vgaHWUnlock(vgaHWPtr hwp)
This function unlocks the VGA CRTC[0-7] registers, and
must be called before attempting to write to those regis-
ters.
A macro VGAHW_UNLOCK(base) is also available in vgaHW.h
that does the same thing, and this may be used when the
vgahw module is not loaded (for example, in the Chip-
Probe() function).
void vgaHWLock(vgaHWPtr hwp)
This function locks the VGA CRTC[0-7] registers.
A macro VGAHW_LOCK(base) is also available in vgaHW.h
that does the same thing, and this may be used when the
vgahw module is not loaded (for example, in the Chip-
Probe() function).
void vgaHWSave(ScrnInfoPtr pScrn, vgaRegPtr save, int flags)
This function saves the VGA state. The state is written
to the vgaRegRec pointed to by save. flags is set to one
or more of the following flags ORed together:
VGA_SR_MODE
the mode setting registers are saved
VGA_SR_FONTS
the text mode font/text data is saved
VGA_SR_CMAP
the colourmap (LUT) is saved
VGA_SR_ALL
all of the above are saved
The vgaHWRec and its IOBase fields must be initialised
before this function is called. If VGA_SR_FONTS is set
in flags, the VGA memory window must be mapped. If it
isn't then vgaHWMapMem() will be called to map it, and
vgaHWUnmapMem() will be called to unmap it afterwards.
vgaHWSave() uses the three functions below in the order
vgaHWSaveColormap(), vgaHWSaveMode(), vgaHWSaveFonts() to
carry out the different save phases. It is undecided at
this stage whether they will be part of the vgahw mod-
ule's public interface or not.
void vgaHWSaveMode(ScrnInfoPtr pScrn, vgaRegPtr save)
This functions saves the VGA mode registers. They are
saved to the vgaRegRec pointed to by save. The registers
saved are:
MiscOut
CRTC[0-0x18]
Attribute[0-0x14]
Graphics[0-8]
Sequencer[0-4]
void vgaHWSaveFonts(ScrnInfoPtr pScrn, vgaRegPtr save)
This functions saves the text mode font and text data
held in the video memory. If called while in a graphics
mode, no save is done. The VGA memory window must be
mapped with vgaHWMapMem() before to calling this func-
tion.
On some platforms, one or more of the font/text plane
saves may be no-ops. This is the case when the plat-
form's VC driver already takes care of this.
void vgaHWSaveColormap(ScrnInfoPtr pScrn, vgaRegPtr save)
This function saves the VGA colourmap (LUT). Before sav-
ing it, it attempts to verify that the colourmap is read-
able. In rare cases where it isn't readable, a default
colourmap is saved instead.
void vgaHWRestore(ScrnInfoPtr pScrn, vgaRegPtr restore, int flags)
This function programs the VGA state. The state pro-
grammed is that contained in the vgaRegRec pointed to by
restore. flags is the same as described above for the
vgaHWSave() function.
The vgaHWRec and its IOBase fields must be initialised
before this function is called. If VGA_SR_FONTS is set
in flags, the VGA memory window must be mapped. If it
isn't then vgaHWMapMem() will be called to map it, and
vgaHWUnmapMem() will be called to unmap it afterwards.
vgaHWRestore() uses the three functions below in the
order vgaHWRestoreFonts(), vgaHWRestoreMode(), vgaHWRe-
storeColormap() to carry out the different restore
phases. It is undecided at this stage whether they will
be part of the vgahw module's public interface or not.
void vgaHWRestoreMode(ScrnInfoPtr pScrn, vgaRegPtr restore)
This functions restores the VGA mode registers. They are
restore from the data in the vgaRegRec pointed to by
restore. The registers restored are:
MiscOut
CRTC[0-0x18]
Attribute[0-0x14]
Graphics[0-8]
Sequencer[0-4]
void vgaHWRestoreFonts(ScrnInfoPtr pScrn, vgaRegPtr restore)
This functions restores the text mode font and text data
to the video memory. The VGA memory window must be
mapped with vgaHWMapMem() before to calling this func-
tion.
On some platforms, one or more of the font/text plane
restores may be no-ops. This is the case when the plat-
form's VC driver already takes care of this.
void vgaHWRestoreColormap(ScrnInfoPtr pScrn, vgaRegPtr restore)
This function restores the VGA colourmap (LUT).
void vgaHWInit(ScrnInfoPtr pScrn, DisplayModePtr mode)
This function fills in the vgaHWRec's ModeReg field with
the values appropriate for programming the given video
mode. It requires that the ScrnInfoRec's depth field is
initialised, which determines how the registers are pro-
grammed.
void vgaHWSeqReset(vgaHWPtr hwp, Bool start)
Do a VGA sequencer reset. If start is TRUE, the reset is
started. If start is FALSE, the reset is ended.
void vgaHWProtect(ScrnInfoPtr pScrn, Bool on)
This function protects VGA registers and memory from cor-
ruption during loads. It is typically called with on set
to TRUE before programming, and with on set to FALSE
after programming.
Bool vgaHWSaveScreen(ScreenPtr pScreen, Bool on)
This function blanks and unblanks the screen. It is
blanked when on is FALSE, and unblanked when on is TRUE.
void vgaHWBlankScreen(ScrnInfoPtr pScrn, Bool on)
This function blanks and unblanks the screen. It is
blanked when on is FALSE, and unblanked when on is TRUE.
This function is provided for use in cases where the
ScrnInfoRec can't be derived from the ScreenRec, like
probing for clocks.
19.3 VGA Colormap Functions
The vgahw modules uses the standard colormap support (see the Colormap Han-
dling (section 13., page 1) section. This is initialised with the following
function:
Bool vgaHWHandleColormaps(ScreenPtr pScreen)
19.4 VGA Register Access Functions
The vgahw module abstracts access to the standard VGA registers by using a
set of functions held in the vgaHWRec. When the vgaHWRec is created these
function pointers are initialised with the set of standard VGA I/O register
access functions. In addition to these, the vgahw module includes a basic
set of MMIO register access functions, and the vgaHWRec function pointers can
be initialised to these by calling the vgaHWSetMmioFuncs() function described
above. Some drivers/platforms may require a different set of functions for
VGA access. The access functions are described here.
void writeCrtc(vgaHWPtr hwp, CARD8 index, CARD8 value)
Write value to CRTC register index.
CARD8 readCrtc(vgaHWPtr hwp, CARD8 index)
Return the value read from CRTC register index.
void writeGr(vgaHWPtr hwp, CARD8 index, CARD8 value)
Write value to Graphics Controller register index.
CARD8 readGR(vgaHWPtr hwp, CARD8 index)
Return the value read from Graphics Controller register
index.
void writeSeq(vgaHWPtr hwp, CARD8 index, CARD8, value)
Write value to Sequencer register index.
CARD8 readSeq(vgaHWPtr hwp, CARD8 index)
Return the value read from Sequencer register index.
void writeAttr(vgaHWPtr hwp, CARD8 index, CARD8, value)
Write value to Attribute Controller register index. When
writing out the index value this function should set bit
5 (0x20) according to the setting of hwp->paletteEnabled
in order to preserve the palette access state. It should
be cleared when hwp->paletteEnabled is TRUE and set when
it is FALSE.
CARD8 readAttr(vgaHWPtr hwp, CARD8 index)
Return the value read from Attribute Controller register
index. When writing out the index value this function
should set bit 5 (0x20) according to the setting of
hwp->paletteEnabled in order to preserve the palette
access state. It should be cleared when hwp->paletteEn-
abled is TRUE and set when it is FALSE.
void writeMiscOut(vgaHWPtr hwp, CARD8 value)
Write `value' to the Miscellaneous Output register.
CARD8 readMiscOut(vgwHWPtr hwp)
Return the value read from the Miscellaneous Output reg-
ister.
void enablePalette(vgaHWPtr hwp)
Clear the palette address source bit in the Attribute
Controller index register and set hwp->paletteEnabled to
TRUE.
void disablePalette(vgaHWPtr hwp)
Set the palette address source bit in the Attribute Con-
troller index register and set hwp->paletteEnabled to
FALSE.
void writeDacMask(vgaHWPtr hwp, CARD8 value)
Write value to the DAC Mask register.
CARD8 readDacMask(vgaHWptr hwp)
Return the value read from the DAC Mask register.
void writeDacReadAddress(vgaHWPtr hwp, CARD8 value)
Write value to the DAC Read Address register.
void writeDacWriteAddress(vgaHWPtr hwp, CARD8 value)
Write value to the DAC Write Address register.
void writeDacData(vgaHWPtr hwp, CARD8 value)
Write value to the DAC Data register.
CARD8 readDacData(vgaHWptr hwp)
Return the value read from the DAC Data register.
20. Some notes about writing a driver
NOTE: some parts of this are not up to date
The following is an outline for writing a basic unaccelerated driver for a
PCI video card with a linear mapped framebuffer, and which has a VGA core.
It is includes some general information that is relevant to most drivers
(even those which don't fit that basic description).
The information here is based on the initial conversion of the Matrox Millen-
nium driver to the ``new design''. For a fleshing out and sample implementa-
tion of some of the bits outlined here, refer to that driver. Note that this
is an example only. The approach used here will not be appropriate for all
drivers.
Each driver must reserve a unique driver name, and a string that is used to
prefix all of its externally visible symbols. This is to avoid name space
clashes when loading multiple drivers. The examples here are for the ``ZZZ''
driver, which uses the ``ZZZ'' or ``zzz'' prefix for its externally visible
symbols.
20.1 Include files
All drivers normally include the following headers:
"xf86.h"
"xf86_OSproc.h"
"xf86_ansic.h"
"xf86Resources.h"
Wherever inb/outb (and related things) are used the following should be
included:
"compiler.h"
Drivers that need to access PCI vendor/device definitions need this:
"xf86PciInfo.h"
Drivers that need to access the PCI config space need this:
"xf86Pci.h"
Drivers using the mi banking wrapper need:
"mibank.h"
Drivers that initialise a SW cursor need this:
"mipointer.h"
All drivers implementing backing store need this:
"mibstore.h"
All drivers using the mi colourmap code need this:
"micmap.h"
If a driver uses the vgahw module, it needs this:
"vgaHW.h"
Drivers supporting VGA or Hercules monochrome screens need:
"xf1bpp.h"
Drivers supporting VGA or EGC 16-colour screens need:
"xf4bpp.h"
Drivers using cfb need:
#define PSZ 8
#include "cfb.h"
#undef PSZ
Drivers supporting bpp 16, 24 or 32 with cfb need one or more of:
"cfb16.h"
"cfb24.h"
"cfb32.h"
The driver's own header file:
"zzz.h"
Drivers must NOT include the following:
"xf86Priv.h"
"xf86Privstr.h"
"xf86_libc.h"
"xf86_OSlib.h"
"Xos.h"
any OS header
20.2 Data structures and initialisation
o The following macros should be defined:
#define VERSION <version-as-an-int>
#define ZZZ_NAME "ZZZ" /* the name used to prefix messages */
#define ZZZ_DRIVER_NAME "zzz" /* the driver name as used in config file */
#define ZZZ_MAJOR_VERSION <int>
#define ZZZ_MINOR_VERSION <int>
#define ZZZ_PATCHLEVEL <int>
XXX Probably want to remove one of these version.
NOTE: ZZZ_DRIVER_NAME should match the name of the driver module without
things like the "lib" prefix, the "_drv" suffix or filename extensions.
o A DriverRec must be defined, which includes the functions required at
the pre-probe phase. The name of this DriverRec must be an upper-case
version of ZZZ_DRIVER_NAME (for the purposes of static linking).
DriverRec ZZZ = {
VERSION,
"unaccelerated driver for ZZZ Zzzzzy cards",
ZZZIdentify,
ZZZProbe,
NULL,
0
};
o Define list of supported chips and their matching ID:
static SymTabRec ZZZChipsets[] = {
{ PCI_CHIP_ZZZ1234, "zzz1234a" },
{ PCI_CHIP_ZZZ5678, "zzz5678a" },
{ -1, NULL }
};
The token field may be any integer value that the driver may use to
uniquely identify the supported chipsets. For drivers that support only
PCI devices using the PCI device IDs might be a natural choice, but this
isn't mandatory. For drivers that support both PCI and other devices
(like ISA), some other ID should probably used. When other IDs are used
as the tokens it is recommended that the names be defined as an enum
type.
o If the driver uses the xf86MatchPciInstances() helper (recommended for
drivers that support PCI cards) a list that maps PCI IDs to chip IDs and
fixed resources must be defined:
static PciChipsets ZZZPciChipsets[] = {
{ PCI_CHIP_ZZZ1234, PCI_CHIP_ZZZ1234, RES_SHARED_VGA },
{ PCI_CHIP_ZZZ5678, PCI_CHIP_ZZZ5678, RES_SHARED_VGA },
{ -1, -1, RES_UNDEFINED }
}
o Define the XF86ModuleVersionInfo struct for the driver. This is
required for the dynamically loaded version:
#ifdef XFree86LOADER
static XF86ModuleVersionInfo zzzVersRec =
{
"zzz",
MODULEVENDORSTRING,
MODINFOSTRING1,
MODINFOSTRING2,
XF86_VERSION_CURRENT,
ZZZ_MAJOR_VERSION, ZZZ_MINOR_VERSION, ZZZ_PATCHLEVEL,
ABI_CLASS_VIDEODRV,
ABI_VIDEODRV_VERSION,
MOD_CLASS_VIDEODRV,
{0,0,0,0}
};
#endif
o Define a data structure to hold the driver's screen-specific data. This
must be used instead of global variables. This would be defined in the
"zzz.h" file, something like:
typedef struct {
type1 field1;
type2 field2;
int fooHack;
Bool pciRetry;
Bool noAccel;
Bool hwCursor;
CloseScreenProcPtr CloseScreen;
...
} ZZZRec, *ZZZPtr;
o Define the list of config file Options that the driver accepts. For
consistency between drivers those in the list of ``standard'' options
should be used where appropriate before inventing new options.
typedef enum {
OPTION_FOO_HACK,
OPTION_PCI_RETRY,
OPTION_HW_CURSOR,
OPTION_NOACCEL
} ZZZOpts;
static OptionInfoRec ZZZOptions[] = {
{ OPTION_FOO_HACK, "FooHack", OPTV_INTEGER, {0}, FALSE },
{ OPTION_PCI_RETRY, "PciRetry", OPTV_BOOLEAN, {0}, FALSE },
{ OPTION_HW_CURSOR, "HWcursor", OPTV_BOOLEAN, {0}, FALSE },
{ OPTION_NOACCEL, "NoAccel", OPTV_BOOLEAN, {0}, FALSE },
{ -1, NULL, OPTV_NONE, {0}, FALSE }
};
20.3 Functions
20.3.1 SetupProc
For dynamically loaded modules, a ModuleData variable is required. It is
should be the name of the driver prepended to "ModuleData". A Setup() func-
tion is also required, which calls xf86AddDriver() to add the driver to the
main list of drivers.
#ifdef XFree86LOADER
static MODULESETUPPROTO(mgaSetup);
XF86ModuleData zzzModuleData = { &zzzVersRec, zzzSetup, NULL };
static pointer
zzzSetup(pointer module, pointer opts, int *errmaj, int *errmin)
{
static Bool setupDone = FALSE;
/* This module should be loaded only once, but check to be sure. */
if (!setupDone) {
/*
* Modules that this driver always requires may be loaded
* here by calling LoadSubModule().
*/
setupDone = TRUE;
xf86AddDriver(&MGA, module, 0);
/*
* The return value must be non-NULL on success even though
* there is no TearDownProc.
*/
return (pointer)1;
} else {
if (errmaj) *errmaj = LDR_ONCEONLY;
return NULL;
}
}
#endif
20.3.2 GetRec, FreeRec
A function is usually required to allocate the driver's screen-specific data
structure and hook it into the ScrnInfoRec's driverPrivate field. The Scrn-
InfoRec's driverPrivate is initialised to NULL, so it is easy to check if the
initialisation has already been done. After allocating it, initialise the
fields. By using xnfcalloc() to do the allocation it is zeroed, and if the
allocation fails the server exits.
static Bool
ZZZGetRec(ScrnInfoPtr pScrn)
{
if (pScrn->driverPrivate != NULL)
return TRUE;
pScrn->driverPrivate = xnfcalloc(sizeof(ZZZRec), 1);
/* Initialise as required */
...
return TRUE;
}
Define a macro in "zzz.h" which gets a pointer to the ZZZRec when given
pScrn:
#define ZZZPTR(p) ((ZZZPtr)((p)->driverPrivate))
Define a function to free the above, setting it to NULL once it has been
freed:
static void
ZZZFreeRec(ScrnInfoPtr pScrn)
{
if (pScrn->driverPrivate == NULL)
return;
xfree(pScrn->driverPrivate);
pScrn->driverPrivate = NULL;
}
20.3.3 Identify
Define the Identify() function. It is run before the Probe, and typically
prints out an identifying message, which might include the chipsets it sup-
ports. This function is mandatory:
static void
ZZZIdentify(int flags)
{
xf86PrintChipsets(ZZZ_NAME, "driver for ZZZ Tech chipsets",
ZZZChipsets);
}
20.3.4 Probe
Define the Probe() function. The purpose of this is to find all instances of
the hardware that the driver supports, and for the ones not already claimed
by another driver, claim the slot, and allocate a ScrnInfoRec. This should
be a minimal probe, and it should under no circumstances leave the state of
the hardware changed. Because a device is found, don't assume that it will
be used. Don't do any initialisations other than the required ScrnInfoRec
initialisations. Don't allocate any new data structures.
This function is mandatory.
NOTE: The xf86DrvMsg() functions cannot be used from the Probe.
static Bool
ZZZProbe(DriverPtr drv, int flags)
{
Bool foundScreen = FALSE;
int numDevSections, numUsed;
GDevPtr *devSections;
int *usedChips;
int i;
/*
* Find the config file Device sections that match this
* driver, and return if there are none.
*/
if ((numDevSections = xf86MatchDevice(ZZZ_DRIVER_NAME,
&devSections)) <= 0) {
return FALSE;
}
/*
* Since this is a PCI card, "probing" just amounts to checking
* the PCI data that the server has already collected. If there
* is none, return.
*
* Although the config file is allowed to override things, it
* is reasonable to not allow it to override the detection
* of no PCI video cards.
*
* The provided xf86MatchPciInstances() helper takes care of
* the details.
*/
/* test if PCI bus present */
if (xf86GetPciVideoInfo()) {
numUsed = xf86MatchPciInstances(ZZZ_NAME, PCI_VENDOR_ZZZ,
ZZZChipsets, ZZZPciChipsets, devSections,
numDevSections, drv, &usedChips);
for (i = 0; i < numUsed; i++) {
ScrnInfoPtr pScrn;
/* Allocate a ScrnInfoRec */
pScrn = xf86AllocateScreen(drv, 0);
pScrn->driverVersion = VERSION;
pScrn->driverName = ZZZ_DRIVER_NAME;
pScrn->name = ZZZ_NAME;
pScrn->Probe = ZZZProbe;
pScrn->PreInit = ZZZPreInit;
pScrn->ScreenInit = ZZZScreenInit;
pScrn->SwitchMode = ZZZSwitchMode;
pScrn->AdjustFrame = ZZZAdjustFrame;
pScrn->EnterVT = ZZZEnterVT;
pScrn->LeaveVT = ZZZLeaveVT;
pScrn->FreeScreen = ZZZFreeScreen;
pScrn->ValidMode = ZZZValidMode;
foundScreen = TRUE;
/* add screen to entity */
xf86ConfigActivePciEntity(pScrn, usedChips[i],
ZZZPciChipsets, NULL, NULL, NULL, NULL, NULL);
}
if (numUsed > 0)
xfree(usedChips);
}
#ifdef HAS_ISA_DEVS
/*
* If the driver supports ISA hardware, the following block
* can be included too.
*/
numUsed = xf86MatchIsaInstances(ZZZ_NAME, ZZZChipsets,
ZZZIsaChipsets, drv, ZZZFindIsaDevice,
devSections, numDevSections, &usedChips);
for (i = 0; i < numUsed; i++) {
ScrnInfoPtr pScrn = xf86AllocateScreen(drv,0);
pScrn->driverVersion = VERSION;
pScrn->driverName = ZZZ_DRIVER_NAME;
pScrn->name = ZZZ_NAME;
pScrn->Probe = ZZZProbe;
pScrn->PreInit = ZZZPreInit;
pScrn->ScreenInit = ZZZScreenInit;
pScrn->SwitchMode = ZZZSwitchMode;
pScrn->AdjustFrame = ZZZAdjustFrame;
pScrn->EnterVT = ZZZEnterVT;
pScrn->LeaveVT = ZZZLeaveVT;
pScrn->FreeScreen = ZZZFreeScreen;
pScrn->ValidMode = ZZZValidMode;
foundScreen = TRUE;
xf86ConfigActiveIsaEntity(pScrn, usedChips[i], ZZZIsaChipsets,
NULL, NULL, NULL, NULL, NULL);
}
if (numUsed > 0)
xfree(usedChips);
#endif /* HAS_ISA_DEVS */
xfree(devSections);
return foundScreen;
20.3.5 PreInit
Define the PreInit() function. The purpose of this is to find all the infor-
mation required to determine if the configuration is usable, and to ini-
tialise those parts of the ScrnInfoRec that can be set once at the beginning
of the first server generation. The information should be found in the least
intrusive way possible.
This function is mandatory.
NOTES:
1. The PreInit() function is only called once during the life of the X
server (at the start of the first generation).
2. Data allocated here must be of the type that persists for the life of
the X server. This means that data that hooks into the ScrnInfoRec's
privates field should be allocated here, but data that hooks into the
ScreenRec's devPrivates field should not be allocated here. The
driverPrivate field should also be allocated here.
3. Although the ScrnInfoRec has been allocated before this function is
called, the ScreenRec has not been allocated. That means that things
requiring it cannot be used in this function.
4. Very little of the ScrnInfoRec has been initialised when this function
is called. It is important to get the order of doing things right in
this function.
static Bool
ZZZPreInit(ScrnInfoPtr pScrn, int flags)
{
/* Fill in the monitor field */
pScrn->monitor = pScrn->confScreen->monitor;
/*
* If using the vgahw module, it will typically be loaded
* here by calling xf86LoadSubModule(pScrn, "vgahw");
*/
/*
* Set the depth/bpp. Our preferred default depth/bpp is 8, and
* we support both 24bpp and 32bpp framebuffer layouts.
* This sets pScrn->display also.
*/
if (!xf86SetDepthBpp(pScrn, 8, 8, 8,
Support24bppFb | Support32bppFb)) {
return FALSE;
} else {
if (depth/bpp isn't one we support) {
print error message;
return FALSE;
}
}
/* Print out the depth/bpp that was set */
xf86PrintDepthBpp(pScrn);
/* Set bits per RGB for 8bpp */
if (pScrn->depth <= 8) {
/* Take into account a dac_6_bit option here */
pScrn->rgbBits = 6 or 8;
}
/*
* xf86SetWeight() and xf86SetDefaultVisual() must be called
* after pScrn->display is initialised.
*/
/* Set weight/mask/offset for depth > 8 */
if (pScrn->depth > 8) {
if (!xf86SetWeight(pScrn, defaultWeight, defaultMask)) {
return FALSE;
} else {
if (weight isn't one we support) {
print error message;
return FALSE;
}
}
}
/* Set the default visual. */
if (!xf86SetDefaultVisual(pScrn, -1)) {
return FALSE;
} else {
if (visual isn't one we support) {
print error message;
return FALSE;
}
}
/* If the driver supports gamma correction, set the gamma. */
if (!xf86SetGamma(pScrn, default_gamma)) {
return FALSE;
}
/* This driver uses a programmable clock */
pScrn->progClock = TRUE;
/* Allocate the ZZZRec driverPrivate */
if (!ZZZGetRec(pScrn)) {
return FALSE;
}
pZzz = ZZZPTR(pScrn);
/* Collect all of the option flags (fill in pScrn->options) */
xf86CollectOptions(pScrn, NULL);
/*
* Process the options based on the information in ZZZOptions.
* The results are written to ZZZOptions.
*/
xf86ProcessOptions(pScrn->scrnIndex, pScrn->options, ZZZOptions);
/*
* Set various fields of ScrnInfoRec and/or ZZZRec based on
* the options found.
*/
from = X_DEFAULT;
pZzz->hwCursor = FALSE;
if (xf86IsOptionSet(ZZZOptions, OPTION_HW_CURSOR)) {
from = X_CONFIG;
pZzz->hwCursor = TRUE;
}
xf86DrvMsg(pScrn->scrnIndex, from, "Using %s cursor\n",
pZzz->hwCursor ? "HW" : "SW");
if (xf86IsOptionSet(ZZZOptions, OPTION_NOACCEL)) {
pZzz->noAccel = TRUE;
xf86DrvMsg(pScrn->scrnIndex, X_CONFIG,
"Acceleration disabled\n");
} else {
pZzz->noAccel = FALSE;
}
if (xf86IsOptionSet(ZZZOptions, OPTION_PCI_RETRY)) {
pZzz->UsePCIRetry = TRUE;
xf86DrvMsg(pScrn->scrnIndex, X_CONFIG, "PCI retry enabled\n");
}
pZzz->fooHack = 0;
if (xf86GetOptValInteger(ZZZOptions, OPTION_FOO_HACK,
&pZzz->fooHack)) {
xf86DrvMsg(pScrn->scrnIndex, X_CONFIG, "Foo Hack set to %d\n",
pZzz->fooHack);
}
/*
* Find the PCI slot(s) that this screen claimed in the probe.
* In this case, exactly one is expected, so complain otherwise.
* Note in this case we're not interested in the card types so
* that parameter is set to NULL.
*/
if ((i = xf86GetPciInfoForScreen(pScrn->scrnIndex, &pciList, NULL))
!= 1) {
print error message;
ZZZFreeRec(pScrn);
if (i > 0)
xfree(pciList);
return FALSE;
}
/* Note that pciList should be freed below when no longer needed */
/*
* Determine the chipset, allowing config file chipset and
* chipid values to override the probed information. The config
* chipset value has precedence over its chipid value if both
* are present.
*
* It isn't necessary to fill in pScrn->chipset if the driver
* keeps track of the chipset in its ZZZRec.
*/
...
/*
* Determine video memory, fb base address, I/O addresses, etc,
* allowing the config file to override probed values.
*
* Set the appropriate pScrn fields (videoRam is probably the
* most important one that other code might require), and
* print out the settings.
*/
...
/* Initialise a clockRanges list. */
...
/* Set any other chipset specific things in the ZZZRec */
...
/* Select valid modes from those available */
i = xf86ValidateModes(pScrn, pScrn->monitor->Modes,
pScrn->display->modes, clockRanges,
NULL, minPitch, maxPitch, rounding,
minHeight, maxHeight,
pScrn->display->virtualX,
pScrn->display->virtualY,
pScrn->videoRam * 1024,
LOOKUP_BEST_REFRESH);
if (i == -1) {
ZZZFreeRec(pScrn);
return FALSE;
}
/* Prune the modes marked as invalid */
xf86PruneDriverModes(pScrn);
/* If no valid modes, return */
if (i == 0 || pScrn->modes == NULL) {
print error message;
ZZZFreeRec(pScrn);
return FALSE;
}
/*
* Initialise the CRTC fields for the modes. This driver expects
* vertical values to be halved for interlaced modes.
*/
xf86SetCrtcForModes(pScrn, INTERLACE_HALVE_V);
/* Set the current mode to the first in the list. */
pScrn->currentMode = pScrn->modes;
/* Print the list of modes being used. */
xf86PrintModes(pScrn);
/* Set the DPI */
xf86SetDpi(pScrn, 0, 0);
/* Load bpp-specific modules */
switch (pScrn->bitsPerPixel) {
case 1:
mod = "xf1bpp";
break;
case 4:
mod = "xf4bpp";
break;
case 8:
mod = "cfb";
break;
case 16:
mod = "cfb16";
break;
case 24:
mod = "cfb24";
break;
case 32:
mod = "cfb32";
break;
}
if (mod && !xf86LoadSubModule(pScrn, mod))
ZZZFreeRec(pScrn);
return FALSE;
/* Load XAA if needed */
if (!pZzz->noAccel || pZzz->hwCursor)
if (!xf86LoadSubModule(pScrn, "xaa")) {
ZZZFreeRec(pScrn);
return FALSE;
}
/* Done */
return TRUE;
}
20.3.6 MapMem, UnmapMem
Define functions to map and unmap the video memory and any other memory aper-
tures required. These functions are not mandatory, but it is often useful to
have such functions.
static Bool
ZZZMapMem(ScrnInfoPtr pScrn)
{
/* Call xf86MapPciMem() to map each PCI memory area */
...
return TRUE or FALSE;
}
static Bool
ZZZUnmapMem(ScrnInfoPtr pScrn)
{
/* Call xf86UnMapVidMem() to unmap each memory area */
...
return TRUE or FALSE;
}
20.3.7 Save, Restore
Define functions to save and restore the original video state. These func-
tions are not mandatory, but are often useful.
static void
ZZZSave(ScrnInfoPtr pScrn)
{
/*
* Save state into per-screen data structures.
* If using the vgahw module, vgaHWSave will typically be
* called here.
*/
...
}
static void
ZZZRestore(ScrnInfoPtr pScrn)
{
/*
* Restore state from per-screen data structures.
* If using the vgahw module, vgaHWRestore will typically be
* called here.
*/
...
}
20.3.8 ModeInit
Define a function to initialise a new video mode. This function isn't manda-
tory, but is often useful.
static Bool
ZZZModeInit(ScrnInfoPtr pScrn, DisplayModePtr mode)
{
/*
* Program a video mode. If using the vgahw module,
* vgaHWInit and vgaRestore will typically be called here.
* Once up to the point where there can't be a failure
* set pScrn->vtSema to TRUE.
*/
...
}
20.3.9 ScreenInit
Define the ScreenInit() function. This is called at the start of each server
generation, and should fill in as much of the ScreenRec as possible as well
as any other data that is initialised once per generation. It should ini-
tialise the framebuffer layers it is using, and initialise the initial video
mode.
This function is mandatory.
NOTE: The ScreenRec (pScreen) is passed to this driver, but it and the Scrn-
InfoRecs are not yet hooked into each other. This means that in this func-
tion, and functions it calls, one cannot be found from the other.
static Bool
ZZZScreenInit(int scrnIndex, ScreenPtr pScreen, int argc, char **argv)
{
/* Get the ScrnInfoRec */
pScrn = xf86Screens[pScreen->myNum];
/*
* If using the vgahw module, its data structures and related
* things are typically initialised/mapped here.
*/
/* Save the current video state */
ZZZSave(pScrn);
/* Initialise the first mode */
ZZZModeInit(pScrn, pScrn->currentMode);
/* Set the viewport if supported */
ZZZAdjustFrame(scrnIndex, pScrn->frameX0, pScrn->frameY0, 0);
/*
* Setup the screen's visuals, and initialise the framebuffer
* code.
*/
/* Reset the visual list */
miClearVisualTypes();
/*
* Setup the visuals supported. This driver only supports
* TrueColor for bpp > 8, so the default set of visuals isn't
* acceptable. To deal with this, call miSetVisualTypes with
* the appropriate visual mask.
*/
if (pScrn->bitsPerPixel > 8) {
if (!miSetVisualTypes(pScrn->depth, TrueColorMask,
pScrn->rgbBits, pScrn->defaultVisual))
return FALSE;
} else {
if (!miSetVisualTypes(pScrn->depth,
miGetDefaultVisualMask(pScrn->depth),
pScrn->rgbBits, pScrn->defaultVisual))
return FALSE;
}
/*
* Initialise the framebuffer.
*/
switch (pScrn->bitsPerPixel) {
case 1:
ret = xf1bppScreenInit(pScreen, FbBase,
pScrn->virtualX, pScrn->virtualY,
pScrn->xDpi, pScrn->yDpi,
pScrn->displayWidth);
break;
case 4:
ret = xf4bppScreenInit(pScreen, FbBase,
pScrn->virtualX, pScrn->virtualY,
pScrn->xDpi, pScrn->yDpi,
pScrn->displayWidth);
break;
case 8:
ret = cfbScreenInit(pScreen, FbBase,
pScrn->virtualX, pScrn->virtualY,
pScrn->xDpi, pScrn->yDpi,
pScrn->displayWidth);
break;
case 16:
ret = cfb16ScreenInit(pScreen, FbBase,
pScrn->virtualX, pScrn->virtualY,
pScrn->xDpi, pScrn->yDpi,
pScrn->displayWidth);
break;
case 24:
ret = cfb24ScreenInit(pScreen, FbBase,
pScrn->virtualX, pScrn->virtualY,
pScrn->xDpi, pScrn->yDpi,
pScrn->displayWidth);
break;
case 32:
ret = cfb32ScreenInit(pScreen, FbBase,
pScrn->virtualX, pScrn->virtualY,
pScrn->xDpi, pScrn->yDpi,
pScrn->displayWidth);
break;
default:
print a message about an internal error;
ret = FALSE;
break;
}
if (!ret)
return FALSE;
/* Override the default mask/offset settings */
if (pScrn->bitsPerPixel > 8) {
for (i = 0, visual = pScreen->visuals;
i < pScreen->numVisuals; i++, visual++) {
if ((visual->class | DynamicClass) == DirectColor) {
visual->offsetRed = pScrn->offset.red;
visual->offsetGreen = pScrn->offset.green;
visual->offsetBlue = pScrn->offset.blue;
visual->redMask = pScrn->mask.red;
visual->greenMask = pScrn->mask.green;
visual->blueMask = pScrn->mask.blue;
}
}
}
/*
* If banking is needed, initialise an miBankInfoRec (defined in
* "mibank.h"), and call miInitializeBanking().
*/
if (!miInitializeBanking(pScreen, pScrn->virtualX, pScrn->virtualY,
pScrn->displayWidth, pBankInfo))
return FALSE;
/*
* If backing store is to be supported (as is usually the case),
* initialise it.
*/
miInitializeBackingStore(pScreen);
/*
* Set initial black & white colourmap indices.
*/
xf86SetBlackWhitePixels(pScreen);
/*
* Install colourmap functions. If using the vgahw module,
* vgaHandleColormaps would usually be called here.
*/
...
/*
* Initialise cursor functions. This example is for the mi
* software cursor.
*/
miDCInitialize(pScreen, xf86GetPointerScreenFuncs());
/* Initialise the default colourmap */
switch (pScrn->depth) {
case 1:
if (!xf1bppCreateDefColormap(pScreen))
return FALSE;
break;
case 4:
if (!xf4bppCreateDefColormap(pScreen))
return FALSE;
break;
default:
if (!cfbCreateDefColormap(pScreen))
return FALSE;
break;
}
/*
* Wrap the CloseScreen vector and set SaveScreen.
*/
ZZZPTR(pScrn)->CloseScreen = pScreen->CloseScreen;
pScreen->CloseScreen = ZZZCloseScreen;
pScreen->SaveScreen = ZZZSaveScreen;
/* Report any unused options (only for the first generation) */
if (serverGeneration == 1) {
xf86ShowUnusedOptions(pScrn->scrnIndex, pScrn->options);
}
/* Done */
return TRUE;
}
20.3.10 SwitchMode
Define the SwitchMode() function if mode switching is supported by the
driver.
static Bool
ZZZSwitchMode(int scrnIndex, DisplayModePtr mode, int flags)
{
return ZZZModeInit(xf86Screens[scrnIndex], mode);
}
20.3.11 AdjustFrame
Define the AdjustFrame() function if the driver supports this.
static void
ZZZAdjustFrame(int scrnIndex, int x, int y, int flags)
{
/* Adjust the viewport */
}
20.3.12 EnterVT, LeaveVT
Define the EnterVT() and LeaveVT() functions.
These functions are mandatory.
static Bool
ZZZEnterVT(int scrnIndex, int flags)
{
ScrnInfoPtr pScrn = xf86Screens[scrnIndex];
return ZZZModeInit(pScrn, pScrn->currentMode);
}
static void
ZZZLeaveVT(int scrnIndex, int flags)
{
ScrnInfoPtr pScrn = xf86Screens[scrnIndex];
ZZZRestore(pScrn);
}
20.3.13 CloseScreen
Define the CloseScreen() function:
This function is mandatory. Note that it unwraps the previously wrapped
pScreen->CloseScreen, and finishes by calling it.
static Bool
ZZZCloseScreen(int scrnIndex, ScreenPtr pScreen)
{
ScrnInfoPtr pScrn = xf86Screens[scrnIndex];
ZZZRestore(pScrn);
ZZZUnmapMem(pScrn);
pScrn->vtSema = FALSE;
pScreen->CloseScreen = ZZZPTR(pScrn)->CloseScreen;
return (*pScreen->CloseScreen)(scrnIndex, pScreen);
}
20.3.14 SaveScreen
Define the SaveScreen() function (the screen blanking function). When using
the vgahw module, this will typically be:
This function is mandatory.
static Bool
ZZZSaveScreen(ScreenPtr pScreen, Bool unblank)
{
return vgaHWSaveScreen(pScreen, unblank);
}
20.3.15 FreeScreen
Define the FreeScreen() function. This function is optional. It should be
defined if the ScrnInfoRec driverPrivate field is used so that it can be
freed when a screen is deleted by the common layer for reasons possibly
beyond the driver's control. This function is not used in during normal
(error free) operation. The per-generation data is freed by the Clos-
eScreen() function.
static void
ZZZFreeScreen(int scrnIndex, int flags)
{
/*
* If the vgahw module is used vgaHWFreeHWRec() would be called
* here.
*/
ZZZFreeRec(xf86Screens[scrnIndex]);
}
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$XFree86: xc/programs/Xserver/hw/xfree86/doc/DESIGN,v 1.5 1999/07/18 08:34:28 dawes Exp $
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