Re: X hardware acceleration still flaky?

[Jon TURNEY <jon dot turney at dronecode dot org dot uk>]

On 10/08/2010 12:00, L.Wood@surrey.ac.uk wrote:
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to thread 5736.0x16c4]
> 0x6fb96c8d in pixman_fill_sse2 () from /usr/bin/cygpixman-1-0.dll
> (gdb) bt
> #0  0x6fb96c8d in pixman_fill_sse2 () from /usr/bin/cygpixman-1-0.dll
> #1  0x6fb97205 in pixman_fill_sse2 () from /usr/bin/cygpixman-1-0.dll
> #2  0x6fb77245 in pixman_fill () from /usr/bin/cygpixman-1-0.dll
> #3  0x0044924b in fbFill (pDrawable=0x109306f8, pGC=0x10936530, x=657, y=367,
>      width=450, height=450) at fbfill.c:48
> #4  0x0044746f in fbPolyFillRect (pDrawable=0x109306f8, pGC=0x10936530,
>      nrect=0, prect=0x1096791c) at fbfillrect.c:77
> #5  0x0052728f in damagePolyFillRect (pDrawable=0x109306f8, pGC=0x10936530,
>      nRects=1, pRects=0x10967914) at damage.c:1404
> #6  0x005504c3 in ProcPolyFillRectangle (client=0x106bd4f0) at dispatch.c:1939
> #7  0x0054c56e in Dispatch () at dispatch.c:439
> #8  0x005465af in main (argc=3, argv=0x61227b64, envp=0x104300f8)
>      at main.c:286

Thanks.

With the details provided in the last couple of emails, I have managed to 
reproduce what I think is the same problem as you are seeing.

1) Start geomview
2) Cause the geomview camera window to start animating, e.g. by loading one of 
the demo scenes and making the camera rotate, or by opening SaVi and starting 
simulated time running
3) Move the camera window away from it's original position up or to the left 
(observe if you move it a small amount to the right or down, the area of scene 
being drawn in it which is updated is constrained to the original window position)

This has nothing to do with 'hardware acceleration' or OpenGL, it seems that 
the particular way this application draws it's output (into a same-size child 
window of the camera window) interacts with the composite extension to expose 
a bug in the XWin code.

You should be able to workaround the crash by starting the X server with 
'-extension Composite' to disable the composite extension.

I've uploaded a build with an attempt at fixing this at [1].  Perhaps you 
could try it out and see if it works for you?

I'm not sure why the image flickers so badly, a double buffered OpenGL visual 
seems to be being used, so only a complete frame should be transferred to the 
display, but I can see elements of the scene being drawn.

[1] ftp://cygwin.com/pub/cygwinx/XWin.20100812-git-7180c693de178032.exe.bz2

--
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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