On Tue, 2009-01-13 at 13:39 -0800, Chris Wright wrote:
* Dave Jones (davej(a)redhat.com) wrote:
> On Tue, Jan 13, 2009 at 09:55:27PM +0100, Gerd Hoffmann wrote:
> > Bill Nottingham wrote:
> > > Here's some proposed config changes.
> > Jumping on the wagon ;)
> > Can we enable CONFIG_DMAR please? This turns on the IOMMU on intel
> > boxes, using VT-d. Called "DMA Remapping" in intel speak, this is
> > the config option name comes from. Advantages:
> > (1) 32bit PCI devices can DMA to memory above 4G, thus the need for
> > swiotlb (i.e. bounce buffers) is gone.
> > (2) It allows kvm to pass through PCI devices to guests securely.
> The last time we tried this, it blew up a lot due to broken BIOSes.
> Maybe it's been improved enough to tolerate them, so we can probably
> give it a spin in rawhide for a while to see what happens.
Upstream was still broken as recently as Friday for bad BIOSes (x200s in
this case). Wonder if opt-in via cmdline would be helpful?
This is now believed to be fixed, and I've re-enabled DMAR in rawhide.
I see Chuck has applied the fix to F-10 already, and we'll look at the
question of re-enabling DMAR there later. For now you still need to boot
F-10 with 'intel_iommu=on'.
David Woodhouse Open Source Technology Centre
David.Woodhouse(a)intel.com Intel Corporation