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

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 05/15/2017 03:51 PM, Gary R Hook wrote:
> So I've been slogging through online docs and the code, trying to
> understand where things stand with PVH.
>
> I think my primary questions are:
>   1) How do I identify a PVHv2/HVMlite guest?
[root@dhcp-burlington7-2nd-B-east-10-152-55-52 ~]# dmesg | grep PVH
[    0.000000] Booting paravirtualized kernel on Xen PVH
[root@dhcp-burlington7-2nd-B-east-10-152-55-52 ~]#


>   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)
> I've got Xen 4.9 unstable built/installed/booted, and am running 4.10
> kernels on my
> dom0 and guests.
domU PVH support has been added in 4.11 kernel so you don't have it.


> I've gotten a guest booted, and a basic Ubuntu 14.04 installed from a
> distro ISO onto a
> raw disk (a logical volume). All good.
>
> If I use the example file /etc/xen/example.hvm to define a simple guest
> (but no VGA:
> nographic=1), I see that I have a qemu instance running, which I expect,
> along with some
> threads:
This is exactly the thing that PVH guests won't have. You are likely 
booting a regular HVM guest.
An PVH guest's config looks something like

        kernel="/root/64/vmlinux"
        builder="hvm"
        device_model_version="none"
        extra="root=/dev/xvda1 console=hvc0"
        memory=8192
        vcpus=2
        name = "pvh"
        disk=['/root/virt/f22.img,raw,xvda,rw']

(note device_model_version)

-boris



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