lkml.org 
[lkml]   [2004]   [Feb]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: IOMMUs was Re: Intel vs AMD x86-64
On Tue, Feb 24, 2004 at 09:50:02AM -0600, richard.brunner@amd.com wrote:
>
> > -----Original Message-----
> > From: Andi Kleen [mailto:ak@suse.de]
>
>
> > On Opteron the IOMMU code (ab)uses the built in AGPv3 GART in
> > the CPU, which
> > was originally intended for AGP. AMD converted it to be able
> > to remap PCI especially for Linux, which I think deserves applause.
> >
> > It works surprisingly well even though it was not designed as
> > a real IOMMU. Of course one of the main advantages of a real
> > IOMMU - preventing arbitary memory corruption from broken
> > devices - is lost because the remapping table is just a hole
> > in the memory. I'm
> > secretly hoping that when there is more support for Linux at
> > chipset vendors they will someday add a bit to isolate all
> > traffic that doesn't go through the GART from the main
> > memory. This way you could get a much more reliable system
> > that can tolerate broken PCI devices at a moderate
> > performance penalty.
>
> Andi is being modest. It was he and Andrea Arcangeli who convinced
> me we had a problem. We found a way to trick the AGP
> GART hardware into helping, and then they turned it into a
> "real" solution and helped us work the warts out of the BIOS
> to enable it.

Yowza! Open source helping to make better processors. :-D
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:01    [W:0.032 / U:0.264 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site