Re: [Xen-devel] Guidance for PVHv2 usage?

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Mon, May 29, 2017 at 10:28:03AM -0700, PGNet Dev wrote:
> On 5/29/17 10:03 AM, Roger Pau Monné wrote:
[...]
> > In any case, please
> > hold off before trying Dom0, it's still not in a working state.
> 
> Does "hold off" -- in this fuzzy interim -- simply mean -- do NOT specify any 
> dom0=XXX?  Or to specify dom0=pvh, or somesuch?

dom0=pvh is what should be used once it's finished. Right now there's
no PVHv2 Dom0 support in Linux, and the Xen side is not finished. If
you manage to get this booting, you are going to hit a panic in Xen
code [0].

> >> and in Guest.cfg
> >>
> >>    builder = 'linux'
> >>    kernel = '/usr/lib/grub2/x86_64-xen/grub.xen'
> >>    xen_platform_pci = 1
> >>    device_model_version = 'qemu-xen'
> >>    ...
> > 
> > I'm not really sure what this guest is, PV I assume?
> 
> Heh.  Well, that's a good question.
> 
> It WAS hvm, and now it's TRYING to be PVHv2.  It's booted atm as SOMETHING 
> ... I suppose it's 'still' PVH.

I think you booted a PV guest.

> That^ config IS what I *used* to use for PVH on Opensuse ...
> 
> > builder = 'linux' is not a valid option [0].
> 
> It is -- or at least, WAS -- for Opensuse's Xen:
> 
>    https://lists.opensuse.org/opensuse-virtual/2016-01/msg00004.html
> 
> Also referenced here:
> 
>    https://patchwork.kernel.org/patch/9368403/

I think builder='linux' should be builder='generic' on the examples
above. It simply works because it's ignored and builder='generic' is
used as the default value.

[...]
> > you will have to
> > direct boot into the kernel you wish to use. For example a suitable
> > config file for PVHv2 would be:
> > 
> > builder='hvm'
> > device_model_version='none'
> > 
> > kernel='/path/to/kernel'
> > ramdisk='/path/to/initrd'
> 
> 
> so, just to be clear, for PVHv2, we'll use =HVM, not PVH (=generic), builder? 
> Even given that PVHv1 is not available anymore, and it _sounds_ like PVHv2 
> will "replace" PVH?

For PVHv2 we want to use "pvh=1" in the config file. Sadly this is not
yet implemented, so the only way to boot a PVHv2 guest is using:

builder='hvm'
device_model_version='none'

Roger

[0] 
http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/x86/hvm/dom0_build.c;hb=HEAD#l1093

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