Mailing List Archive

PVH boot from net?
Hi it is possible to boot from net (PXE) with PVH mode? If yes, can you show me e example config? --------- Greetz
Re: PVH boot from net? [ In reply to ]
Hello,

On Sun, Jan 02, 2022 at 10:36:52PM +0100, Chris wrote:
> Hi it is possible to boot from net (PXE) with PVH mode?

I've been searching around for something like that and I don't
think it is possible.

I think you would have to add Xen PVH support to something like
iPXE.

https://ipxe.org/

You would then either boot iPXE directly as PVH kernel or else boot
PVH grub that then has iPXE as one of its options.

Whatever way you look at it nothing boots under PVH (or PV) without
being modified to do so, and I'm not aware of any PXE kernel that
has been modified that way.

That leaves HVM mode which probably has unmodified firmware that can
do PXE or else it can boot iPXE.

I would be very happy to be told I've missed a solution here.

Cheers,
Andy
Re: PVH boot from net? [ In reply to ]
Hi Chris!

Am 02.01.22 um 22:36 schrieb Chris:
> Hi
> it is possible to boot from net (PXE) with PVH mode?
> If yes, can you show me e example config?
>
Im not sure, what you are looking for. Would you

1. Start xen via ipxe and the start a domU client
2. Using ipxe in a pvh environment

for 1.: I didnt try this yet, but grub is able to start xen so it should
be also possible start xen (with linux as dom0) via ipxe. Then you
should be able to start a pvh client from the dom0 linux. The needed
device can easily be imported i.e. as iscsi devices, so that xen can
offer it.

for 2.: For using ipxe normally a Legacy-Bios or Uefi-Bios is needed.
But PVH per default starts the domU-client directly as i.e a binary with
ELF-header, so no "pxe" ist possible. But in future (I assume this is
work in progress), xen is able to start OVMF as uefi-Bios in PVH-mode so
OVMF is able to start i.e. ipxe for network boot. For this an ipxe-aware
virtual nic is needed (virtio), where I dont know the status quo.
Eventually ipxe is able to use virtio devices and can be built with
ELF-header, so it is startable directly in PVH-mode, but I also dont
know the status quo. You can make a try and see, what happens :-)

Regards,

Oliver
Re: PVH boot from net? [ In reply to ]
Hi Chis,

here is a solution for my first point I wrote in my last email:

https://ipxe.org/appnote/xenserver

Hth,

Oliver

Am 02.01.22 um 22:36 schrieb Chris:
> Hi
> it is possible to boot from net (PXE) with PVH mode?
> If yes, can you show me e example config?
> ---------
> Greetz
Re: PVH boot from net? [ In reply to ]
On Sun, Jan 2, 2022 at 9:38 PM Chris <mangel@gmx.de> wrote:

> Hi
>
> it is possible to boot from net (PXE) with PVH mode?
> If yes, can you show me e example config?
>

Theoretically you should be able to netboot w/ PVH using the same
techniques you would for PV. Description of that here:

https://wiki.xenproject.org/wiki/Xenpvnetboot

I haven't tested it myself however; if it doesn't work definitely let us
know.

-George