Re: PCIe device pass-through - No IOMMU, Failed to deassign device error

[Chris Wright <chrisw@sous-sol.org>]

* Kenni Lund (kenni@kelu.dk) wrote:
> 2010/1/26 Kenni Lund <kenni@kelu.dk>:
> > 2010/1/26 Chris Wright <chrisw@sous-sol.org>:
> >>
> >> Again, VT (or VT-x) isn't the same as VT-d.  So to be sure, you can
> >> grep dmesg for DMAR and IOMMU to verify that the chipset actually has
> >> VT-d support, that it's enabled, and that it's not broken (there are
> >> quite a few broken BIOS out there that case the IOMMU to be unusable).
> >
> > dmesg | egrep (DMAR|IOMMU)
> > This information should _really_ be added to the wiki at
> > http://www.linux-kvm.org/page/How_to_assign_devices_with_VT-d_in_KVM
> >
> > Knowing this, it's quite easy for a user to determine if his system
> > has VT-d support, _before_ following the guide, compiling own kernel,
> > setting up qemu-kvm, unbinding and rebinding PCI devices, just to have
> > qemu-kvm 0.12.2 tell him that the system has no IOMMU (much better
> > than 0.12.1, agreed, but it's a bit late in the process to find out
> > :))
> 
> Doh, I didn't consider if the kernel compilation probably were needed
> to give any output - nevertheless, I still think this should be added
> to the wiki, even if it's the case. Perhaps a short text describing
> what you should look for.

Sure, I added a short snippet.

thanks,
-chris