Re: Possible Pentium MMX CPU bug?

Thomas Wouters (thomas@xs4all.nl)
Fri, 28 Nov 1997 18:31:34 +0100 (CET)


On Fri, 28 Nov 1997, linux kernel account wrote:

> > (centurion:~) # ./mw_bug
> > testing bug ... no Pentium MMX 'missed write' bug in this CPU.
> >
> > And I have a Stepping 3 Pentium/MMX 200. Compiled the program with both gcc
> > 2.7.2.1 (Standard RedHat version) and with egcs-2.90.17p (pgcc) with various
> > optimizations, ran it under kernel 2.0.30 (standard RedHat version) and
> > 2.1.66.

> Perhaps PGCC silently fixes the problem..

No: the problem was that the standard redhat kernel is compiled with -D386
instead of -D586. The 2.1 kernel doesn't expose the bug. Compiling a new
2.0.32 kernel (with pgcc, but with gcc IMO would yield no difference) did
expose the bug.

So the 'bug' or 'feature' is definately there.