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Date: Fri, 7 Nov 1997 14:27:14 -0600 (CST)
From: Alex Nash <nash@Mcs.Net>
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.

I (well, gcc) had a few syntactical problems with your program.  Here's a
fixed version:

unsigned char x[] = { 0xf0, 0x0f, 0xc7, 0xc8 };

main ()
{
  void (*f)(void) = (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?

Also crashes:

CPU: Pentium (166.59-MHz 586-class CPU)
  Origin = "GenuineIntel"  Id = 0x52c  Stepping=12
  Features=0x1bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8>

Alex