Re: [Xen-devel] Xen PVH support in grub2

[Boris Ostrovsky]

On 11/03/2017 02:23 PM, Juergen Gross wrote:
> On 03/11/17 19:19, Boris Ostrovsky wrote:
>> On 11/03/2017 02:05 PM, Juergen Gross wrote:
>>> So again the question: how to tell whether we are PVH or HVM in
>>> init_hypervisor_platform()? ACPi tables are scanned way later...
>> Can we make grub/OVMF append a boot option?
>>
>> Or set setup_header.hardware_subarch to something? We already have
>> X86_SUBARCH_XEN but it is only used by PV.  Or we might be able to use
>> hardware_subarch_data (will need to get a buy-in from x86 maintainers, I
>> think).
> But wouldn't this break the idea to reuse the native boot paths in
> grub/OVMF without further modifications?

WDYM? We will have to have some sort of a plugin in either one to build
the zeropage anyway. So we'd set hardware_subarch there, in addition to
other things like setting memory and such.

-boris

>
> I'd rather have a way to ask the hypervisor whether we are in PVH mode
> (e.g. via CPUID or a hypercall to test for a devicemodel having itself
> registered).
>
> In case we need to set an indicator in zeropage I'd opt for reusing
> X86_SUBARCH_XEN.
>
>
> Juergen