[PATCH] power: Fix VSCR position on ucontext

[Tulio Magno Quites Machado Filho]

"Gabriel F. T. Gomes" <gabriel@inconstante.eti.br> writes:

> [ text/plain ]
> On Fri, 07 Dec 2018, Rogerio Alves wrote:
>
>>+/* This test is supported only on POWER 5 or higher.  */
>>+#define PPC_CPU_SUPPORTED (PPC_FEATURE_POWER5 | PPC_FEATURE_POWER5_PLUS | \
>>+                           PPC_FEATURE_ARCH_2_05 | PPC_FEATURE_ARCH_2_06 | \
>>+                           PPC_FEATURE2_ARCH_2_07)
>
> Is this actually needed?  Glibc has code to fill all the bits for older
> architectures in sysdeps/powerpc/hwcapinfo.c [1].  So, as far as I can
> see, you only need to test for AT_HWCAP & PPC_FEATURE_POWER5.

Yes, it's indeed required to check all these bits when using getauxval().

> [1] https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/powerpc/hwcapinfo.c;h=a09b18309324423d0cdf04e88367899a4396bab7;hb=HEAD#l47

This code is preparing the data for __builtin_cpu_supports().
So, when using this built-in, it wouldn't be necessary to check for all those
AT_HWCAP bits.

-- 
Tulio Magno