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Date: Fri, 14 Feb 2003 15:25:15 +0100 (MET)
From: Peter Finderup Lund <firefly@diku.dk>
To: Robert Dewar <dewar@gnat.com>
cc: tjm@codegen.com, <discuss@x86-64.org>, <linux-kernel@vger.kernel.org>,
       <peter@jazz-1.trumpet.com.au>
Subject: Re: [discuss] Re: [Bug 350] New: i386 context switch very slow
 compared to 2.4 due to wrmsr (performance)
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On Fri, 14 Feb 2003, Robert Dewar wrote:

> > > The only way to get from long-mode back to legacy-mode is to reset the
> > > processor.  It can be done in software but you will likely lose interrupts.
> >
> > Smartdrv.sys and triple-faults come back, all is forgiven!  ;)
>
> I have an idea, perhaps we can make the keyboard controller recognize a special
> command that will reset the processor :-) :-)

What if there was an undocumented instruction otherwise only used for
testing and CPU in-circuit-emulation to load all the internal state of the
CPU from memory?  Maybe that would work?

-Peter




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