Re: [PATCH 1/2] powerpc/64s: Fix GENERIC_CPU build flags for PPC970 / G5

["Nicholas Piggin" <npiggin@gmail.com>]

On Thu Sep 22, 2022 at 4:50 AM AEST, Segher Boessenkool wrote:
> On Wed, Sep 21, 2022 at 11:41:02AM +1000, Nicholas Piggin wrote:
> > Big-endian GENERIC_CPU supports 970, but builds with -mcpu=power5.
> > POWER5 is ISA v2.02 whereas 970 is v2.01 plus Altivec. 2.02 added
> > the popcntb instruction which a compiler might use.
> > 
> > Use -mcpu=power4.
> > 
> > Fixes: 471d7ff8b51b ("powerpc/64s: Remove POWER4 support")
> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>
> Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
>
> Thank you!
>
> Maybe superfluous, but some more context: GCC's -mcpu=power4 means
> POWER4+, ISA 2.01, according to our documentation.  There is no
> difference with ISA 2.00 (what plain POWER4 implements) for anything
> GCC does.

Huh, okay. Well I guess we are past that point now, interesting that
another ISA version was done for 4+ though, and then another for 5.
I don't see a list of changes from 2.00 in the public version, I
wonder what else changed other than mtmsrd.

Thanks,
Nick