Re: HVMlite ABI specification DRAFT B + implementation outline

[David Vrabel <david.vrabel@citrix.com>]

On 09/02/16 16:15, Jan Beulich wrote:
>>>> On 09.02.16 at 16:06, <stefano.stabellini@eu.citrix.com> wrote:
>> On Tue, 9 Feb 2016, Jan Beulich wrote:
>>> Will STAO be sufficient for everything that may need customization?
>>> I'm particularly worried about processor related methods in DSDT or
>>> SSDT, which - if we're really meaning to do as you say - would need
>>> to be limited (or extended) to the number of vCPU-s Dom0 gets.
>>> What's even less clear to me is how you mean to deal with P-, C-,
>>> and (once supported) T-state management for CPUs which don't
>>> have a vCPU equivalent in Dom0.
>>
>> It is possible to use the STAO to hide entire objects, including
>> processors, from the DSDT, which should be good enough to prevent dom0
>> from calling any of the processor related methods you are referreing to.
>> Then we can let Xen do cpuidle and cpufreq as it is already doing.
>>
>> Would that work? Or do we still need Dom0 to call any ACPI methods for
>> power management?
> 
> We want two things at once here, which afaict can't possibly work:
> On one hand we want Dom0 to only see ACPI objects corresponding
> to its own vCPU-s. Otoh we need Dom0 to see all objects, in order
> to propagate respective information to Xen.

Could dom0 query Xen for the machine ACPI tables via a hypercall?

David