[Xcb] X server bug on BIG-REQUESTS?
iano at quirkster.com
Sat Jun 10 09:55:46 PDT 2006
On Jun 9, 2006, at 9:54 PM, Jamey Sharp wrote:
> On my system, my test app reports the following:
> maximum request length in 4-byte units: 4194303
> creating a 1024x1024 pixmap (1048576 pixels, 4194304 bytes)
> create.sequence = 3; put.sequence = 0
> XCBFlush failed.
> XCBPollForEvent: I/O error occured, but no handler provided.
> At this point I believe we've identified an X server bug, and I think
> the error is in the ReadRequestFromClient function in os/io.c, but
> function is incomprehensible to me. I think the symptom is that this
> function is incorrectly returning -1 (causing a call to
> in Dispatch) when we send it this large request. It's worth noting the
> comment that says, "Watch out: needed sometimes counts bytes and
> sometimes counts CARD32's," which sounds like exactly the kind of
> confusion we're seeing.
For what its worth, this also happens on the XFree86 4.4.0 server
shipped with Mac OS X. Either this bug has been around a
long time, or it isn't really a server bug.
(More data: 1023x1024 and 1022x1025 works, but 1023x1025 fails, even
that size is 4194300 bytes, less than 4194303 max length.)
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