Re: [Xen-devel] We still have to disable vtd for old chipset?

["Neo Jia" <neojia@xxxxxxxxx>]

I just tried it by removing the checking. The following is from my xm
dmesg. Does those warning matter?


(XEN) [VT-D]iommu.c:1722: Queued Invalidation hardware not found
(XEN) [VT-D]iommu.c:1722: Queued Invalidation hardware not found
(XEN) [VT-D]iommu.c:1722: Queued Invalidation hardware not found
(XEN) [VT-D]iommu.c:1722: Queued Invalidation hardware not found
(XEN) [VT-D]iommu.c:1730: Interrupt Remapping hardware not found
(XEN) [VT-D]iommu.c:1730: Interrupt Remapping hardware not found
(XEN) [VT-D]iommu.c:1730: Interrupt Remapping hardware not found
(XEN) [VT-D]iommu.c:1730: Interrupt Remapping hardware not found
(XEN) I/O virtualisation enabled
(XEN) [VT-D]iommu.c:1241:d32767 context_context_mapping: nested PCI
bridge not supported: bdf = 0:9:0 sec_bus = 3 sub_bus = 7
(XEN) [VT-D]iommu.c:1241:d32767 context_context_mapping: nested PCI
bridge not supported: bdf = 3:0:0 sec_bus = 4 sub_bus = 6
(XEN) *** LOADING DOMAIN 0 ***


Thanks,
Neo

On Tue, Jun 3, 2008 at 8:36 AM, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> wrote:
> Kay, Allen M writes ("RE: [Xen-devel] We still have to disable vtd for old 
> chipset?"):
>> It should work assuming your BIOS is reporting VT-d correctly.  At least
>> the page table sharing should no longer be the issue.
>
> Are you sure ?  My understanding (admittedly half-remembered from some
> technical note that came with the motherboard replacement to bring our
> pre-C0 pre-production VT-d system up to date) was that the iommu page
> table format is different in the pre-C0 chipsets.
>
> That would explain why pagetable sharing between iommu and normal mmu
> is not possible with those chipsets.  But it also makes those pre-C0
> chipsets completely incompatible with all of the code in Xen, because
> Xen doesn't know anything about those pre-C0 pagetables ?  (And isn't
> going to be taught.)
>
> Ian.
>



-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

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