tree 298d0f96e6aa6bc414d3e7ad2db765ea8e864cff
parent e2ce07c8042975e52df4cec1f41faf15b83f2e42
author Krzysztof Helt <krzysztof.h1@wp.pl> 1222809471 +0200
committer Ingo Molnar <mingo@elte.hu> 1223886793 +0200

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>