Bug#423739: libgl1-mesa-dri: banding in rendering when using blending for transparency
Hi, Michel (sorry for the spurious "a"...),
Please try verifying the indication that it's a Debian specific issue.
E.g., does building the patched Debian source tree the same way as you
built the upstream tree produce a working or defect r200_dri.so? Are the
same compiler flags used? ...
If I build from the patched Debian source tree as I would from the upstream tree
("make linux-dri-x86") the test program works properly. If I use a
debian-specific
config ("make debian-dri-i386" or debian/rules), the test program fails,
but in a different way from the failure I reported before (rather than
seeing banding
in the output square, I see an non-50%-gray square whose color fluctuates over
X server restarts, e.g. #98A5AF then #98A57F, etc.).
The debian-specific config uses -O2 instead of -O. In fact, it turns
out that everything
works fine with the debian-dri-i386 if I compile everything at -O2 except for
src/mesa/drivers/dri/r200/r200_span.c which must be compiled with the
-fno-regmove
flag in order to work properly.
None of these builds have replicated the banding I saw with the debian binaries.
Incidentally, I don't actually need to restart the X server to
differentiate between
working and defective libraries, the failure seems dependent on the version of
r200_dri.so loaded when I execute the test program, and not at all
dependent on the
version of r200_dri.so loaded on X server startup (even if the two don't match).
FWIW, I'm using with Debian's gcc 4.1.2-3.
Let me know if there is a good place to keep looking, or if this is of
any help? It
seems like it would be a pity to compile all the DRI drivers at -O
rather than -O2 just
to address such a relatively minor issue...
Thanks,
Dan
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