Bug#464962: Do AMD K7 family CPUs support long noops?
On Wed, Feb 13, 2008 at 01:53:24PM -0800, H. Peter Anvin wrote:
> Graham wrote:
> >Hello,
> >
> >I am wondering whether anyone has looked into which AMD CPUs support
> >these instructions. I would think that installing a 486 kernel on an
> >AthlonXP, for example, would be quite sub-optimal.
> >
> >i.e. can you safely enable X86_P6_NOP for other CPUs, such as AMD
> >K7/K8, VIA C3/C7, or Efficeon? If not, would it be more sensible to
> >avoid using these instructions?
> >
> >It appears that at least some VIA C3 CPUs do not support these opcodes:
> >
> >http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=463606#45
> >
>
> Attached is a C program which tests this.
Via Epia SP8000 (C3)
Long NOPs supported: no
cts@chumley:~>cat /proc/cpuinfo
processor : 0
vendor_id : CentaurHauls
cpu family : 6
model : 9
model name : VIA Nehemiah
stepping : 8
Via Epia EN15000 (C7)
Long NOPs supported: yes
cts@spyder:~>cat /proc/cpuinfo
processor : 0
vendor_id : CentaurHauls
cpu family : 6
model : 10
model name : VIA Esther processor 1500MHz
stepping : 9
Christian
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