It appears that X servers up to at least X.org 7.0 and back as far as the MacOS
X release of XFree86 4.4 can't handle BIG-REQUESTS that are as big as they
advertise support for.
The symptom: if a client makes a request that is bigger than 1/4th the limit
advertised in the BigRequestsEnable reply, the X server closes the connection.
Here is an XCB-based test program that demonstrates the bug:
From inspection of server sources, I speculate that the bug is in os/io.c, in
the ReadRequestFromClient function. I haven't been able to dig deeper than that
because that function scares me, but the comment in that file saying, "Watch
out: needed sometimes counts bytes and sometimes counts CARD32's," seems suspicious.
Ick. Marking as blocker.
Sorry about the phenomenal bug spam, guys. Adding xorg-team@ to the QA contact so bugs don't get lost in future.
Move to 7.3 tracker.
Pushed to master, awaiting cherry-pick to stable.
*** Bug 10672 has been marked as a duplicate of this bug. ***