Re: Direct access to hardware

From: Horst von Brand (vonbrand@inf.utfsm.cl)
Date: Wed Jul 26 2000 - 09:15:38 EST

James Sutherland <jas88@cam.ac.uk> said:
> On 25 Jul 2000, Krzysztof Halasa wrote:

[...]

> > So what does the kernel (can) do to prevent this problem on defective
> > pentiums?

> Trap the defective instructions, and implement a replacement instruction
> in software.

How so? The kernel doesn't look at each instruction before it is
executed... it does clean up _after_ the fact, or arranges so that the bug
can be caught when it tries to bite (f00f case). This is _very_ different
from exhaustively checking beforehand (as is being adovocated here), and it
is done in cases where the fix is cheap (luckily). 

-- 
Dr. Horst H. von Brand                       mailto:vonbrand@inf.utfsm.cl
Departamento de Informatica                     Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria              +56 32 654239
Casilla 110-V, Valparaiso, Chile                Fax:  +56 32 797513

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