From: Krzysztof Helt <krzysztof.h1@wp.pl>
Date: Tue, 30 Sep 2008 21:17:51 +0000 (+0200)
Subject: x86: do not allow to optimize flag_is_changeable_p() (rev. 2)
X-Git-Tag: v2.6.28-rc1~611^2~31
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=94f6bac1058fd59a8bd472d18c4b77f220d930b0;p=pandora-kernel.git

x86: do not allow to optimize flag_is_changeable_p() (rev. 2)

The flag_is_changeable_p() is used by
has_cpuid_p() which can return different results
in the code sequence below:

 if (!have_cpuid_p())
      identify_cpu_without_cpuid(c);

  /* cyrix could have cpuid enabled via c_identify()*/
  if (!have_cpuid_p())
      return;

Otherwise, the gcc 3.4.6 optimizes these two calls
into one which make the code not working correctly.

Cyrix cpus have the CPUID instruction enabled before
the second call to the have_cpuid_p() but
it is not detected due to the gcc optimization.
Thus the ARR registers (mtrr like) are not detected
on such a cpu.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

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