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

[Juergen Gross]

On 03/11/17 20:00, Boris Ostrovsky wrote:
> On 11/03/2017 02:40 PM, Juergen Gross wrote:
>> On 03/11/17 19:35, Boris Ostrovsky wrote:
>>> 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.
>> But isn't the zeropage already being built? I admit that setting subarch
>> isn't a big deal, but using another entry with a passed-through pvh
>> start struct isn't either...
> 
> I don't follow, sorry. My understanding is that zeropage will be built
> by PVH-enlightened grub so part of this process would be setting the
> subarch bit.

My reasoning was based on Roger's remark:

"OTOH if Linux is capable of booting from the native entry point inside
of a PVH container, we would only have to port OVMF and grub in order
to work inside of a PVH container, leaving the rest of the logic
untouched."


Juergen