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Date: Fri, 07 Dec 2018 19:23:00 -0000
From: "Gabriel F. T. Gomes" <gabriel@inconstante.eti.br>
To: Rogerio Alves <rcardoso@linux.ibm.com>
CC: Florian Weimer <fweimer@redhat.com>, <libc-alpha@sourceware.org>
Subject: Re: [PATCH] power: Fix VSCR position on ucontext
Message-ID: <20181207162959.5e5d8933@tereshkova>
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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.

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

>+static int
>+do_test (void)
>+{
>+
>+  if (!(getauxval(AT_HWCAP2) & PPC_CPU_SUPPORTED))
>+    {
>+      if (!(getauxval(AT_HWCAP) & PPC_CPU_SUPPORTED))
>+      FAIL_UNSUPPORTED("This test is unsupported on POWER < 5\n");
>+    }

Similarly.