Re: [gentoo-dev] Modular X plans

[Ferris McCormick]

On Tue, 2005-08-09 at 19:40 -0700, Donnie Berkholz wrote:
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> Good catch. I was going to get to the rest of the GL headers after
> getting Mesa working.

Another comment about Mesa.  Mesa, as distributed, has "built in"
architectures it can build for, and it substitutes its own idea of
appropriate CFLAGS rather than using the user's request.  For sparc, at
least, these are not appropriate, as can be seen from current
xorg-x11-6.8.99.15, say, for which libGL does get built using
make.conf's CFLAGS.

If fact, I think this is a regression.  I know that at one point, at
least, I had opened a bug on this, and it was resolved.  I can't find
any record of it, though, at bugs.freedesktop.org (my original was filed
long ago at sourceforge).

The point is that libGL performance is important for those who use it,
and on sparc, we meed to keep whatever the user asked for with -mcpu=xxx
(-mv8 is just wrong on ultrasparc unless you can't build with it for
some reason, but libGL can build with it).  Further, and problems with
using sparc assembly on linux were corrected long ago, so sparc really
should -DUSE_SPARC_ASM. I am sure the USE_SPARC_ASM bit is also a
regression, because I remember when Mesa was corrected to figure out
correctly whether or not ultrasparc was building for 32-bit user mode or
for 64-bit user mode. (Mesa-6.3.1.1 uses "#ifdef __arch64__" as the
test, and it turns out that gcc does not define this just for
-mcpu=ultrasparc[3], so assembly code should be fine.)

For reference, current xorg-x11 (on ultrasparc3) builds libGL with,
among lots of other CFLAGS, "-O2 -mcpu=ultrasparc3 -DUSE_SPARC_ASM ..."
the first two of which are taken from my CFLAGS.

Of course, all of this might be irrelevant, but I'd rather raise the
concern and be beat up on now than come back later and say "Oh, by the
way, libGL build is all messed up on sparc." :-)

(Point is that xorg-x11 nowadays gets libGL & friends right for
linux-sparc, but Mesa by itself does not, and has regressed from earlier
versions.  So X Modular should configure Mesa as it does now --- for
xorg --- not as Mesa has built-in, which looks wrong.)

Regards,
Ferris
-- 
Ferris McCormick (P44646, MI) <fmccor@g.o>
Developer, Gentoo Linux (Sparc, Devrel)