[Pkg-fglrx-devel] Bug#579813: ../../src/xcb_io.c:445: _XReply: Assertion `!dpy->xcb->reply_data' failed.

[The Wanderer]

On 05/03/2010 01:49 PM, Jamey Sharp wrote:

> It's important to understand that you aren't looking for code that
> calls XCB: you're looking for code that calls Xlib.

Yes, I do understand that. In hindsight, my question was more or less
equivalent to "does this mean that, if Wine actually does call libx11
directly, this could still be a Wine bug?", and the answer to that seems
a self-evident "yes". We should still rule out library/driver bugs as
much as possible before going that direction, though.

> Or grab xtrace, which is packaged in Debian, and read its man page.

I actually did this yesterday, shortly before leaving for work. Attached
please find the result of

xtrace /tmp/wow &> /tmp/wow-winedebug-try3

(where /tmp/wow is a slightly-debugging-modified version of a simple
wrapper script which calls Wine with the correct environment for WoW to
actually run right).

> I wish somebody would write a how-to for this, 'cause I don't have
> time... :-/

As far as I can tell, xtrace's invocation really is as brain-dead simple
as such things get... it certainly seems to be much simpler than dealing
with Wireshark, unless I've done something wrong. For basic usage, at
least, a howto there seems to be as simple as "stick 'xtrace ' at the
beginning of your command line".

> In general, if you normally run 'foo -v quux', try 'gdb --args foo -v
> quux' instead, then 'run'. After the assertion fails, type 'bt full'
> and send the resulting output. This is a lot more useful if you have
> libbaz-dbg installed for every libbaz used by your application. At
> least libx11-6-dbg would be a good start.

I'm familiar with doing that (well, 'gdb foo' and 'run -v quux'), but I
could have sworn that last time I tried it on a failed assertion, the
'bt full' returned no information, because the running program had
already exited because of the failed assertion. If the xtrace isn't
useful enough, I can go try it again anyway.

> However, Wine may have or require special ways to attach a debugger.
> I don't know.

I know Wine does complicated and crazy things, enough so that they've
got their own complex debugging infrastructure (possibly even more
complicated than what I know about the kernel debugging infrastructure,
which is saying something), and I've never been able to get a handle on
how to use that infrastructure.

>> I do have an 'strace -f' log of a run in which this failure
>> occurred, but I suspect that's not going to be useful.
> 
> Yeah, I don't think I could get enough out of the read syscalls to
> replace the protocol trace, and I don't think I want to try. :-)

I already tried it myself, and I know I didn't manage it.
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