[Xorg-driver-geode] proposal: always build with -march=geode

[Martin-Éric Racine]

On Wed, Jun 23, 2010 at 12:04 AM, Gaetan Nadon <memsize at videotron.ca> wrote:
> On Tue, 2010-06-22 at 23:41 +0300, Martin-Éric Racine wrote:
>
> On Tue, Jun 22, 2010 at 11:27 PM, Gaetan Nadon <memsize at videotron.ca> wrote:
>> On Tue, 2010-06-22 at 22:12 +0300, Martin-Éric Racine wrote:
>>
>> In addition to exiting gracefully with a warning at ./configure time
>> if the build host is non-x86, what if we enforced -march=geode if GCC
>>
>> You may want to look at AX_GCC_X86_CPUID and AX_GCC_ARCHFLAG which would
>> do
>> that for you.
>> http://www.gnu.org/software/autoconf-archive/The-Macros.html#The-Macros
>
> > Unless I misunderstood the description, these macros guess the target
> > based on the build host's architecture?
>
> They use host_cpu (e.g. i*86) first and then look at the cpuid. You might
> have cross-compiling in mind.
> Generally speaking, there is not much one can do in configure.ac for
> cross-compiling.

Matching the HOSTCC architecture is not what we're trying to achieve.

Instead, we simply want to ensure that if HOSTCC runs on some x86
variant i.e. atom/x86_32/x86_64 then we'll enforce -march=geode to
ensure that we don't accidentally produce code that won't run on a
Geode and to simultaneously produce Geode-optimized code as a bonus.

However, if HOSTCC runs on some non-x86 architecture, we'll skip
building the module entirely and produce a warning along the lines of
"W: xf86-video-geode only builds and runs on x86_32 architectures.
Skipping this module."

Martin-Éric