DragonFly kernel List (threaded) for 2007-10
DragonFly BSD
DragonFly kernel List (threaded) for 2007-10
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Re: pmap of amd64


From: Joerg Sonnenberger <joerg@xxxxxxxxxxxxxxxxx>
Date: Sat, 13 Oct 2007 14:54:21 +0200
Mail-followup-to: kernel@crater.dragonflybsd.org

On Fri, Oct 12, 2007 at 07:54:16PM -0700, Matthew Dillon wrote:
>     (1) We can map a page containing the address of the per-cpu globaldata
>         structure and use %fs in the trap code:
>  
>         movq	$SOME_FIXED_CONSTANT_ADDRESS,%fs

You don't have to play such games on AMD64 -- the swapgs instruction is
normally used by traps and system calls to load a well-defined address
base for that. Note that gs is expected to be used for, but that is a
minor detail.

Joerg



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