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Re: [PATCH] powerpc: Add basic support for POWER9 sans hwcap.
- From: Peter Bergner <bergner at vnet dot ibm dot com>
- To: Tulio Magno Quites Machado Filho <tuliom at linux dot vnet dot ibm dot com>
- Cc: Carlos Eduardo Seo <cseo at linux dot vnet dot ibm dot com>, GLIBC <libc-alpha at sourceware dot org>, "Steven J. Munroe" <sjmunroe at us dot ibm dot com>
- Date: Wed, 23 Dec 2015 09:44:43 -0600
- Subject: Re: [PATCH] powerpc: Add basic support for POWER9 sans hwcap.
- Authentication-results: sourceware.org; auth=none
- References: <56688E89 dot 7040500 at linux dot vnet dot ibm dot com> <87oadi2x9h dot fsf at totoro dot br dot ibm dot com> <1450814850 dot 3482 dot 31 dot camel at vnet dot ibm dot com> <87eged1hq3 dot fsf at totoro dot br dot ibm dot com>
On Wed, 2015-12-23 at 10:18 -0200, Tulio Magno Quites Machado Filho wrote:
> Peter Bergner <firstname.lastname@example.org> writes:
> > I have no problems with this being committed, but I do ask that
> > if we cannot get the HWCAP bits settled (waiting on the kernel
> > people) before the next glibc release, that we back this out
> > before the release. I don't think having the AT_PLATFORM and
> > AT_HWCAP/AT_HWCAP2 masks out of sync is a good thing for the
> > release.
> Could you elaborate more on why do you think this isn't a good thing for the
> release, please?
I don't want us to get into the situation where the user can do a
__builtin_cpu_is ("power9") that returns true and which implies a
certain feature(s) (eg, IEEE 128), but the __builtin_cpu_supports (...)
returns false for something that should be there on POWER9.