Re: [Xen-devel] Questions about PVHv2/HVMlite

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 05/16/2017 11:52 AM, Gary R Hook wrote:
> On 05/15/2017 09:54 PM, Boris Ostrovsky wrote:
>>
>
> Possibly stupid question time...
>
>> On 05/15/2017 03:51 PM, Gary R Hook wrote:
>>
>>>   2) Or, perhaps more importantly, what distinguishes said guest?
>>
>> Simplifying things a bit, it's an HVM guest that doesn't have device
>> model (i.e. qemu) and which is booted directly (i.e. without hvmloader)
>
> So, an unmodified/stock kernel which would rely upon a typical (i.e. its
> own grub) bootloader. The magic comes from the PVH drivers?

Typically there is no bootloader (or, one might say, the hypervisor is
the bootloader). You indicate which kernel to boot in the config file
(just like for PV guests).

I believe there is some work going on with OVMF that will make it boot
in PVH mode. It will then mount the guest filesystem and load the
kernel. I think that's what Andrew was referring to.

>
>> domU PVH support has been added in 4.11 kernel so you don't have it.
>
> You refer to the drivers?

The drivers are the same as what we use for PV-HVM. It's kernel itself
(mostly the startup code) that was modified.

>
>> An PVH guest's config looks something like
>>
>>     kernel="/root/64/vmlinux"
>
> May I ask from whence this kernel came?

One of 4.11's rcs. Make sure you set CONFIG_XEN_PVH in your .config file.

-boris


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