[Xcb] mesa +xcb = assertion death

[Jeremy Kolb]

Okay, the error is in getting the reply for GLXGetFBConfigs (and 
GLXGetFBConfigsSGI which is just an alias for the former) in 
AllocAndFetchScreenConfigs.  From there it goes:
_XReply -> XCBWaitForReply -> _xcb_conn_wait

The problem occurs in _xcb_conn_wait at:

if ((ret = _xcb_read_int(c) >= 0)

then in xcb_in_read_packet in _xcb_read_int().  This is were it gets 
confusing.  When xcb_in_read_packet returns the value of 
c->in.request_read suddenly becomes 65536 on my computer but I couldn't 
find where it was set to that... it simply became that when the function 
returned (using ddd with gdb as the debugger).

Can someone else verify this?  Simply compile mesa against your xcbified 
xlibs and make sure you're using indirect rendering (if you use the 
nvidia drivers etc you'll need to find a server with the default 
server-side glx).

Jeremy