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SubjectRe: [PATCH] Intel clock speed detection
On Tue, 30 Dec 1997 p0thead@ooz.net wrote:
> I'm a little confuised.. I just tried to run this on my nexgen-90, and it
> gave me this:
>
> [root@metallica /root]# ./mhz.estimate
> Illegal Instruction (core dumped)
>
> Now, does this program only work on pentium's, i'm a little confused.

Yeah, that's the deal. It crashed with "Illegal Instruction" because
your Nexgen chip doesn't have that instruction. (Probably because it
was still undocumented while your NexGen was being made...)

Rumors abound however that the AMD K6 implements rdtsc. All
post-pentium Intel x86 processors such as the PPro and Pentium II
implement it also. Apparently it doesn't work on 6x86's. I haven't
heard anything on the 6x86MX chips but I'd imagine it would support
it. Likewise, I'd take a guess and say the K5 doesn't. (But hey why
guess when you can conduct surveys on busy mailing lists? ;)

If you want something that works on your NexGen, I suggest you
contact Phile Brutsche <pbrutsch@creighton.edu> as he claims to
have code that does this a little more portably.

> > Phile Brutsche wrote:
> > >On another note, I just looked at your patch. It uses the rdtsc
> > >instruction;
> > >this instruction does not exist on anything less than a Pentium.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > >I'm not sure what the kernel would do on '486 or '386, but it
> > >would'nt be pretty. A better solution for this would be to time the bsf
> > >instruction on those chips. I have source in C and assembly if you need
> > >help.
--
Robert Woodcock - robert@olex.com
All I want is a warm bed and a kind word and unlimited power.
-- Ashleigh Brilliant





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