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Date: Fri, 07 Nov 1997 16:20:35 -0800
From: Julian Elischer <julian@whistle.com>
Organization: Whistle Communications
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To: Robert Eckardt <roberte@MEP.Ruhr-Uni-Bochum.de>
CC: "David E. Cross" <dec@phoenix.its.rpi.edu>, hackers@FreeBSD.ORG
Subject: Re: Newest Pentium bug (fatal)
References: <199711080009.BAA00399@ghost.mep.ruhr-uni-bochum.de>
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Robert Eckardt wrote:
> 
> It was David E. Cross who wrote:
> > 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.
> [...]
> > > 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)
> 
> Just tested:
>      CPU: Pentium (133.64-MHz 586-class CPU)
>        Origin = "GenuineIntel"  Id = 0x52c  Stepping=12
>        Features=0x1bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8>
> 
> It crashes (just lost my most recent mailbox, though I had synced!).
> This is 2.2.2-RELEASE.
> 
> I also tested DOS-6.2 w/ TurboC-2.0
> in 8088/8086-model it still reacts on Numlock and Ctrl-Alt-Del.
> in 80186/80286-mode it crashes too.

in 8086 mode, does adding a '0xc3' on the end of the sequence make
any difference?