SIGSEGV in xorg-1.8.2.0 during -resize operation

[Jon TURNEY]

On 12/08/2010 17:07, Jon TURNEY wrote:
> On 12/08/2010 16:49, Ryan Johnson wrote:
>> On 8/12/2010 5:46 PM, Jon TURNEY wrote:
>>> On 10/08/2010 06:48, Ryan Johnson wrote:
>>>> On 8/10/2010 12:02 AM, Jon TURNEY wrote:
>>>>> On 09/08/2010 22:14, Ryan Johnson wrote:
>>>>>> When I detached the monitor to leave the office, X disappeared with
>>>>>> signal 11
>>>>>> (log attached). Oddly, the log file didn't mention -resize as an
>>>>>> argument to
>>>>>> XWin, but it did attempt to resize so I assume the feature was active.
>>>
>>> Oh dear. Well it seems I only thought I added code to only enable resize
>>> support in multiwindow mode when requested, so it's always on for
>>> multiwindow mode at the moment. That wouldn't be so bad, but it also seems
>>> that the -resize code completely fails to correctly handle a change of
>>> colour depth (e.g. from 32 bits to 16 bits or vice versa) leading to this
>>> segfault.
>>>
>>> Unfortunately, fixing this looks to be quite complex :-(
>>>
>>> Thanks for testing, anyhow :-)
>> So... does that mean I have to roll back or face a seg fault after every
>> commute? Or is there a way to explicitly disable it?
>
> I'm afraid so. As I say, I meant to add a means to disable -resize in
> -multiwindow mode to avoid exactly this kind of situation.
>
> Since it's the transition from 32bpp to 16bpp which breaks this, one possible
> workaround would be to run your large monitor at 16bpp, which might also give
> you working resize.

Okay, I think I have worked out the correct thing to do do to handle bpp 
changes in the RANDR code, and I've uploaded a test build at [1].  Perhaps you 
could try it and see if it works for you?

Note that you will need to use -resize with this build to turn on RANDR in any 
mode.

If you can make this crash, with or without -resize, a backtrace would be very 
helpful.

[1] ftp://cygwin.com/pub/cygwinx/XWin.20100831-git-5fa9c90425fb1d68.exe.bz2

-- 
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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