Re: [PATCH 0/2]Add Variable Page Size and IA64 Support in Intel IOMMU

[Bjorn Helgaas]

On Wednesday 01 October 2008 10:56:06 am Fenghua Yu wrote:
> The following two patches (Intel IOMMU generic patch and ia64 specific patch) together enable Intel IOMMU on IA64 platform. They are applied cleanly on the latest linux-next tree which contains Intel IOMMU interrupt remapping and VT-d driver KVM support code.

General comment (not ia64-related): it looks like you detect the
IOMMU using the static DMAR table.  Does the IOMMU also appear in
PCI config space or the ACPI namespace?  I expect it would, because
the fact that the DMAR table is static precludes any sort of hot-plug
to add or remove IOMMUs.

If it *is* in config space or the namespace, it would be good to
exercise that discovery path to help shake out firmware bugs.  For
example, arch/ia64/hp/common/sba_iommu.c uses acpi_bus_register_driver()
to discover HP IOMMUs.  I wouldn't hold the sba_iommu.c discovery code
(most of which I take the blame for) up as a shining example of how to
do things, but it shows the point.

Bjorn
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