Re: [PATCH 1/10] Cr4 is valid on some 486s

[Linus Torvalds <torvalds@osdl.org>]

On Tue, 15 Nov 2005, Zachary Amsden wrote:
> 
> It's not overkill in the virtualization context, and there are (struggling,
> but infinite possibilities) opportunities for native here as well.

No, there are almost no opportunities for native.

Especially with SMP, doing on-line code switching is really really nasty. 
You basically have to shut down all CPU's to make sure there are no races 
with other CPU's executing the code while it's being rewritten.

I'd be very very nervous about it. It would have to be some major 
performance feature for it to make sense over a simple "switch function 
pointers around" approach.

		Linus
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