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Mail Archives: cygwin/1997/11/09/05:04:41

From: swarnerx3 AT acadia DOT net (Scott Warner)
Subject: Re: WARNING: Serious Pentium Bug
9 Nov 1997 05:04:41 -0800 :
Message-ID: <199711091248.HAA29549.cygnus.gnu-win32@p2.acadia.net>
Mime-Version: 1.0
To: <gnu-win32 AT cygnus DOT com>

As a point of curiosity, what is this program supposed to do?  It looks
like it is assigning a pointer to function to a character array.  Possibly
for assember instructions?  What is it about the code that crashes a
Pentium?

> > There is a SERIOUS bug in all pentium CPUs. The following 
> > code will crash any machine running on a pentium CPU, MMX or no 
> > MMX, any speed, regardless of OS (crash as in instant seize, hard 
> > reboot the only cure):
> > 
> > char x [5] = { 0xf0, 0x0f, 0xc7, 0xc8 };
> > 
> > main ()
> > {
> >        void (*f)() = x;
> >        f();
> > }
> > 
> > This require no special permissions to run, it works fine with
> > average-joe-userspace permissions. I have verified this, it works.
> > Demand a new CPU from Intel.
> > 

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