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

["Cui, Dexuan" <dexuan.cui@xxxxxxxxx>]

Keir Fraser wrote:
> On 19/10/2009 15:46, "Cui, Dexuan" <dexuan.cui@xxxxxxxxx> wrote:
> 
>>> 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". 
>> 
>> BTW: from my crash log, you can see the bogus info -- actually the
>> host doesn't support SC, QI and IR.
>> (XEN) Intel VT-d Snoop Control supported.
>> (XEN) Intel VT-d DMA Passthrough not supported.
>> (XEN) Intel VT-d Queued Invalidation supported.
>> (XEN) Intel VT-d Interrupt Remapping supported.
>> (XEN) I/O virtualisation enabled
> 
> Ah, hm, well maybe you need that too. Actually I checked in a slightly
> broader check as c/s 20342, which checks that
> !list_empty(acpi_drhd_units). If you have no such units then
> initialising IOMMU support is rather pointless. And if you did not do
> ACPI bootstrap then you cannot have parsed any units. So the check is
> at least as strong as checking !acpi_disabled, I think.
> 
> Hopefully everyone will be happy that this unlikely corner case,
> requiring the user to have actually shot themselves in the foot by
> manually specifying two contradictory boot parameters, is now solved
> to their satisfaction. ;-) 
Yes, I think 20342 should fix the issue. :-)

Thanks,
-- Dexuan


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