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>]

Miroslav Rezanina wrote:
>>> 
>>> Hi Dexuan,
>>> you're right. We should print warning. In your patch, I do not
>>> understand why you put comment only in setup_dom0_devices function.
>>> There is more calling of domain_context_mapping and we check NULL
>>> also in domain_context_unmap and reassign_device_ownership. We
>>> should put warning in there too, shouldn't we?
>> 
>> The warnings are silly, if we believe find_matched_drhd_unit() should
>> not
>> return NULL in those cases. Since obviously we wouldn't know what to
>> do in
>> that case: bailing and doing nothing, while convenient and requiring
>> little
>> thought to implement, probably causes other subtler problems later on
>> since
>> those remap functions are supposed to actually do something! Crashing
>> immediately is the nice thing to do here: nice for the poor developer
>> who
>> may have to debug this case sometime in the future, in the hopefully
>> unlikely event our belief turns out to be false.
>> 
>> I'll be applying Dexuan's original replacement patch.
>> 
>>  -- Keir
>> 
> 
> I retest version with removed NULL checks and in this case, my system
> crashes. So there has to be checks for NULL or something else is
> wrong. 
> 
> Regards,
> Mirek
Hi Mirek, 
Do you mean: with changeset 20338: 5f28661bb2bb and "acpi=off iommu=1", xen 
crashes in your host?
Can you post the entire serial log?

Thanks,
-- Dexuan

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