Xorg segmentation fault when drawing PolyArcs (under kicad)

Michel Dänzer michel at daenzer.net
Tue Oct 20 05:06:36 PDT 2009

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

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.

Earthling Michel Dänzer           |                http://www.vmware.com
Libre software enthusiast         |          Debian, X and DRI developer

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