Re: [Buildroot] [PATCH v2 1/1] arch/Config.in.x86: consolidate Geode CPU targets

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

On Tue,  1 Aug 2023 12:10:12 -0500
Vincent Fazio <vfazio@gmail.com> wrote:

> Since its introduction in 7d8a59b40, the BR2_x86_geode CPU target has
> pointed to GCC -march=geode which targets AMD Geode processors [0].
> 
> This arch tuning enables MMX and 3DNow! extensions in GCC but these are
> not currently reflected in the selected flags by BR2_x86_geode.
> 
> This is likely due to the confusing naming and history of "Geode".
> 
> The AMD Geode can trace its origins back to the Cyrix MediaGXm [1] and
> then to the NSC Geode GXm/GXLV/GX1/GX2 [2]. All of these processors have
> MMX instruction support listed in their datasheets. The NSC GX2 was the
> first in the series to enable 3DNow!.
> 
> When 7fed07d3a4a introduced BR2_X86_CPU_HAS_MMX, Geode was skipped
> presumably because it wasn't clear that the target is AMD Geode and
> because the Wikipedia documentation for Geode is incomplete [2] with
> regards to supported instructions as they all support MMX.
> 
> When f6cd56b9ce3 introduced BR2_X86_CPU_HAS_3DNOW, Geode was skipped
> presumably for similar reasons.
> 
> Note: the in-tree olpc_xo1_defconfig uses BR2_x86_geode which is fine
> as this hardware uses the AMD Geode [3].
> 
> Make it more clear that the target is AMD Geode by renaming the Kconfig
> menu option and add both MMX and 3DNow! flags to BR2_x86_geode.
> 
> [0]: https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/config/i386/geode.md;;hb=HEAD
> [1]: https://en.wikipedia.org/wiki/MediaGX#MediaGXm
> [2]: https://en.wikipedia.org/wiki/Geode_%28processor%29
> [3]: https://wiki.laptop.org/go/Hardware_specification
> 
> Signed-off-by: Vincent Fazio <vfazio@gmail.com>
> ---
> Changes v1 -> v2:
>   - Reword the commit message
> ---
>  arch/Config.in.x86 | 16 ++--------------
>  1 file changed, 2 insertions(+), 14 deletions(-)

I have further extended the commit log to explain that
BR2_x86_geode_mmx is removed, and that we don't need legacy handling
for this removal, as this option has never been part of a released
version of Buildroot.

Applied with this tweak. Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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