[Xcb] mesa +xcb = assertion death

Jeremy Kolb jkolb at brandeis.edu
Tue May 3 21:11:01 PDT 2005

Jeremy Kolb wrote:
> Jamey Sharp wrote:
>> On Fri, 2005-04-29 at 18:06 -0400, Jeremy Kolb wrote:
>>> Jamey Sharp wrote:
>>>>> However I have no idea why the generic reply is returning 0 as a 
>>>>> sequence number, nor do I know what response_type 5 is.
>>>> Response type 5 is a ButtonRelease event. (0 is an error, 1 is a reply,
>>>> and everything else is an event; you can look up core events in
>>>> xproto.xml, xproto.h, or your friendly neighborhood X protocol
>>>> reference.)
>>> I saw that but disregarded it since no button has been hit at this 
>>> point, indeed there isn't a window and this happens in both glxgears 
>>> (eventually spawns a window when this problem doesn't occur) and 
>>> glxinfo (no window ever).
>> Ethereal, run on your tcpdump trace, clearly says that a bunch of events
>> with sequence number 0 immediately follow the reply to the last GLX
>> request made. But they look like nonsense events to me (weird timestamps
>> and window IDs; and getting KeymapNotify, ButtonRelease, EnterNotify,
>> KeymapNotify, DestroyNotify, ColormapNotify, nonexistent event 39, and
>> then the entire same sequence again seems quite improbable). I suspect
>> your X server is busted, and is reporting the wrong length on the
>> GLXVendorPrivateWithReply reply. Dunno why it would do that, of course.
>> Today I saw your blog entries on this, BTW. Sorry, can't say I agree
>> that it's XCB's fault. ;-)
>> --Jamey
> Jamey I just compiled the latest Xorg from cvs, pointing to all the 
> right libs and tried it on this fresh one running on vesa and I still 
> get the assertion error so I'm not sure if it's the server.
> Jeremy

Okay, I've been trying to narrow it down so I recompiled vanilla cvs 
Mesa against the standard non xcb-ified xlibs.

1) glxgears using Xorg 6.8.2 and NVidia drivers: no problem.
2) glxgears using Xorg 6.8.2 libs and Mesa: no problem.
3) glxgears using xlibs from cvs with XCB enabled: error.
4) glxgears using xlibs from cvs with XCB enabled and Mesa: error.
5) glxgears using xlibs from cvs with XCB enabled and NVidia drivers: error.

This is with Mesa compiled against Xorg 6.8.2 xlibs in /usr/X11R6/lib. 
My xlibs --with-xcb is in /opt/fdo/lib.  And 'using' above means 
modifying LD_LIBRARY_PATH to point to /opt/fdo/lib or nothing at all.  I 
used ldd `which glxgears` after each LD_LIBRARY_PATH change to verify. 
The assertion failure only seems to happen while using X11 with XCB 
support enabled :(


More information about the xcb mailing list