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RE: [Xen-devel] RE: [Xen-changelog] [xen-unstable]vt-d: Fixpanic in msi_msg_read_remap_rte with acpi=off

Keir Fraser wrote:
> On 19/10/2009 15:18, "Cui, Dexuan" <dexuan.cui@xxxxxxxxx> wrote:
>>> So sorry about that. I'll revert Dexuan's patch.
>>>  -- Keir
>> But, can't you reproduce the crash I mentioned before?
>> Please see the attached crash log -- I'm using c/s
>> 20341:ea34183c5c11 and with "iommu=1 acpi=off" and I use a DQ35 host.
>> Actually what I care is the " if ( acpi_disabled ) iommu_enabled =
>> 0". 
> Does this really save you though? 
Do you mean we can leave the crash mentioned in my crash.log as it it? Looks 
not a good idea.

> What if you specify just "iommu=1"
> on an ACPI system that doesn't have VT-d (and therefore declares no
> DHRD units)? 
In such a case, acpi_dmar_init() would return -ENODEV and clear iommu_enabled 
to 0;
later iommu_setup() would actually do nothing to try to enable VT-d, and would 
print  "I/O virtualisation disabled".
This is the expected correct behavior.

-- Dexuan

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