[Xen-devel] Re: [PATCH] Fix xen hang on intel westmere-EP

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 23/08/2011 04:52, "Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx> wrote:

>> Further I'm opposed to introducing further instances of legacy brute- force
>> PCI
>> bus scans.
>> 
>> And I don't think you got something along these lines accepted into Linux,
>> did
>> you? It ought to be DMI based there, too.
> I don't know why you think using DMI is a better way? For BDF based way, we
> only need to know the device ID. But for DMI base way, I don't know which
> condition should be matched.
> 
> Actually, the best way to solve it is to enable the ACPI mode in Xen instead
> of in dom0. For enable ACPI, we need to write the value from FADT.ACPI_ENABLE
> to SMI_CMD. After writing the value, the SMI ownership will be disable by ACPI
> hardware and it also will disable some logic which is able to cause SMI. For
> example, the legacy USB circuit will be masked too. Because at this point,
> there have no need to use legacy usb emulation. This is also what linux
> upstream did. But I think it is too complicated to port this logic to xen.
> Anyway, if you have interesting, you can add this logic to xen and there have
> no need for this patch again.

It sounds like quite a good idea, and not very complicated at all. The main
concern would be potential other fall out from making the change.

 -- Keir



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