Xorg segmentation fault when drawing PolyArcs (under kicad)

Renato Caldas seventhguardian at gmail.com
Tue Oct 20 05:32:54 PDT 2009


Thanks for looking into this!

2009/10/20 Michel Dänzer <michel at daenzer.net>:
> On Mon, 2009-10-12 at 20:12 +0100, Renato Caldas wrote:
>> Hello,
>> First of all, I'm not subscribed to this list, so please include my
>> e-mail in the CC.
>> When using (trying to use...), kicad I managed to get consistent Xorg
>> segmentation faults. I've filed a bug report on fedora's bugzilla:
>> https://bugzilla.redhat.com/show_bug.cgi?id=528475. There I've
>> included a very basic test case that works all the time. In the
>> meantime, I've also got my hands dirty, and tried to debug Xorg using
>> gdb.
>> The symptom is that the function fbBltOne is called with src=0x0, so
>> Xorg segfaults as soon as it tries to use src (in LoadBits; at
>> fb/fbbltone.c:292).
>> I've traced its value back to fbPushPixels, where it is created and
>> fed to the function chain, in the macro fbGetStipDrawable (defined at
>> fb/fb.h:720).
>> Here pDrawable->type seems to be DRAWABLE_PIXMAP, so _pPix is simply
>> cast from pDrawable. Then the _pPix -> devPrivate.ptr is used as
>> "src", after a couple of castings and copying around.
> Please provide a full backtrace ('bt full' in gdb) from when the crash
> occurs.

Attached. I've also attached it to the bug report, just in case.

> If you're using EXA, the problem is most likely that some code path
> isn't calling exaPrepareAccess(Reg) for the pixmap in question before
> calling down to the fb module.

I am using EXA. I'll try enabling XAA and report back.

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