From owner-freebsd-hackers  Fri Nov  7 11:50:31 1997
Return-Path: <owner-freebsd-hackers>
Received: (from root@localhost)
          by hub.freebsd.org (8.8.7/8.8.7) id LAA19121
          for hackers-outgoing; Fri, 7 Nov 1997 11:50:31 -0800 (PST)
          (envelope-from owner-freebsd-hackers)
Received: from phoenix.its.rpi.edu (phoenix.its.rpi.edu [128.113.161.45])
          by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id LAA19113
          for <hackers@FreeBSD.ORG>; Fri, 7 Nov 1997 11:50:18 -0800 (PST)
          (envelope-from dec@phoenix.its.rpi.edu)
Received: from localhost (dec@localhost)
	by phoenix.its.rpi.edu (8.8.7/8.8.7) with SMTP id OAA10286;
	Fri, 7 Nov 1997 14:49:55 -0500 (EST)
	(envelope-from dec@phoenix.its.rpi.edu)
Date: Fri, 7 Nov 1997 14:49:55 -0500 (EST)
From: "David E. Cross" <dec@phoenix.its.rpi.edu>
To: Julian Elischer <julian@whistle.com>
cc: hackers@FreeBSD.ORG
Subject: Re: Newest Pentium bug (fatal)
In-Reply-To: <3463605C.41C67EA6@whistle.com>
Message-ID: <Pine.BSF.3.96.971107144655.8219C-100000@phoenix.its.rpi.edu>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: owner-freebsd-hackers@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

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?
> 
> 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>
> 

CPU: Pentium (132.96-MHz 586-class CPU)
  Origin = "GenuineIntel" Id = 0x52c Stepping=12
  Features=0x1bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8>

Just tested OK for me (no crash)

--
David Cross