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From: noname@noname.com
Newsgroups: comp.os.linux.advocacy
Subject: This code will lock up any P5 machine, even usermode Linux!  (F0 0F C7 C8)
Date: Thu, 06 Nov 1997 21:57:33 -0800
Organization: The University of Texas at Austin, Austin, Texas
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Hi,

        Check this out.  If you execute F0 0F C7 C8 on a P5 it will lock the
machine up.  This is true for any operating system including usermode
Linux.  It's pretty cool.  Basically, the opcodes are an invalid form of
cmpxchg8b eax with a lock prefix.  Has anyone seen this before?  The
problem doesn't show itself for the Pentium Pro or Pentium 2.