Re: [Xen-devel] [PATCH] hvmloader / qemu-xen: Getting rid of resource conflict for OpRegion.

["G.R." <firemeteor@xxxxxxxxxxxxxxxxxxxxx>]

On Fri, Dec 21, 2012 at 3:50 AM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> On Thu, 2012-12-20 at 13:03 +0000, Keir Fraser wrote:
>> On 20/12/2012 10:41, "Ian Campbell" <Ian.Campbell@xxxxxxxxxx> wrote:
>> > Do we need to worry about what is in the "slop" at either end of a 3
>> > page region containing this? If they are sensitive registers then we may
>> > have a problem.
>>
>> In the hvmloader patch it is not worth it I think, one extra page of memory
>> hole is hardly a scarce resource.
>
> I didn't mean the wastage, I meant the contents (registers) at the
> physical addresses either immediately before or after the OpRegion.
>
The bad news is that we have no idea.
In section 2.3, the spec mentions that the firmware is responsible to
create the OpRegion upon boot.
So the layout may be firmware specific.

But I think we need to get confirmation from ACPI / firmware
experts.Who will that be?

Please remember that even the bundle potentially worsen the case, the
potential hole is already open
in the current code-base.
I think you should take action to evaluate the risk whether this patch
is accepted or not.

Thanks,
Timothy

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