Re: [git pull] drm patches for 2.6.27-rc1

[Linus Torvalds]

On Sat, 18 Oct 2008, Jon Smirl wrote:
> 
> Is it possible to use a segment register to map the whole aperture on
> 32b?

No. Segment registers don't extend the virtual address space, they can 
only limit visibility into the one single 32-bit one.

IOW, segment registers don't actually extend addressing in any way, they 
only limit it. There's a reason why people don't use them (except as a 
strange base register for things like per-cpu or per-thread variables, and 
that is not to extend the address space, but to avoid wasting precious 
_useful_ registers on that).

			Linus
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