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Date: Fri, 7 Nov 1997 14:10:26 -0800 (PST)
From: Howard Lew <digital@www2.shoppersnet.com>
To: Julian Elischer <julian@whistle.com>
cc: hackers@FreeBSD.ORG
Subject: Re: Newest Pentium bug (fatal)
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On Fri, 7 Nov 1997, Julian Elischer wrote:

> On a "genuine Intel" pentium (not pentium pro)
> execution of the following sequence, 0xf0 0x0f 0xc7 0xc8
> 
> will stop the processor. This is doable from user mode and in 
> 16bitmode, or in fact any mode.
> 
> try the following c program.
> 
> 
> 
> 
> unsigned char x[] = { 0xfo, 0x0f, 0xc7, 0xc8 };
> 
> 
> main ()
> {
>   void (*f)(void) = x;
>   f();
> }
> 
> 
> 
> 
> We've checked:
> K5... OK
> P6...  OK
> P5...   *SPLAT*
> 
> no idea about the pentium II or other pentium copies.
> K6?
> 
> other pentium variants?
> versions?

On a Cyrix 6x86MX, it just dumps core:
Illegal instruction (core dumped)

> 
> this one DEFINITLY dies:
> CPU: Pentium (99.38-MHz 586-class CPU)
>   Origin = "GenuineIntel"  Id = 0x525  Stepping=5
>   Features=0x1bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8>
> 
> 
> share and enjoy..
> julian
>