Re: [Xen-devel] [PATCH v1 00/20] Make ACPI builder available to components other than hvmloader

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 07/07/2016 04:35 AM, Jan Beulich wrote:
>>>> On 06.07.16 at 18:32, <boris.ostrovsky@xxxxxxxxxx> wrote:
>> On 07/06/2016 12:04 PM, Roger Pau Monné wrote:
>>> On Tue, Jul 05, 2016 at 03:04:59PM -0400, Boris Ostrovsky wrote:
>>>> * Don't set HW_REDUCED_ACPI flags: this flag is only available starting 
>>>> with ACPI v5
>>> Hm, I still think HW_REDUCED_ACPI should be set for the time being, 
>>> considering that we don't provide PM timer or RTC for example. Not setting 
>>> this would be a violation of the ACPI specification, and would mean 
>>> introducing Xen specific hacks yet again to guest OSes, in order to disable 
>>> those devices.
>>>
>>> Is the fact that HW_REDUCED_ACPI was introduced in ACPI v5 a problem?
>> Yes, because we build v2 tables and they are somewhat different.
> So couldn't we switch to building v5 tables (or even v6) for PVH
> (and perhaps re-using the "acpi=" config setting to allow specifying a
> version - with any value above 1 indicating the requested version)? I
> certainly agree that setting a v5 flag in a v2 table is bad (best we can
> hope for is that any consumer would ignore such a flag).

Hmm... I thought earlier that v2 and v5(+) tables are different but now
that I went back this doesn't seem to be the case. It's v1 vs v2 that
changed formats.

If that's the case (I'll check more carefully) then yes, we can provide
PVH guests with higher versions.

-boris



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