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Re: Altivec in baseline for ppc64?



Hi Sébastien!

On 7/13/21 1:55 PM, Sébastien Villemot wrote:
> The wiki page that synthesizes architecture specificities indicates
> that Altivec is included in the baseline for the ppc64 port:
> https://wiki.debian.org/ArchitectureSpecificsMemo#ppc64
> 
> However my understanding is that this port supports any powerpc64 CPU,
> including some that don’t have Altivec (e.g. POWER4 or POWER5). This is
> also what the main wiki page for PPC64 says:
> https://wiki.debian.org/PPC64
> 
> Can someone please clarify the situation?

The ppc64 originally used the ppc64 baseline including AltiVec e.g PowerPC970,
(64-Bit PowerMac). However, the previous port maintainer decided he wanted to
support embedded systems such as the PowerPC E5500 which does not support
AltiVec.

I wasn't really a fan of that change but my stance is that we should use AltiVec
in packages where it makes sense as the majority of the ppc64 port users will
have a machine that suppport AltiVec.

If they run into an issue with these packages on non-AltiVec systems, they can still
file a bug.

> (I’m asking because I’m the maintainer of the openblas package, and
> knowing whether Altivec is available or not, and more generally what is
> in the baseline, is essential for proper packaging).

Please go ahead and enabled AltiVec as I don't think it makes much sense to use BLAS
on machines without any SIMD support. If any user complains about compatibility issues,
please feel free to bring up the issue here again.

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913


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