[et-mgmt-tools] Xen, New VM wizard, paravirt vs full virt

[Cole Robinson]

On 06/25/2009 07:52 PM, Craig Miskell wrote:
> Hi,
>   I'm running virt-manager 0.7.0 on Ubuntu, connecting using SSH to
> libvirt running on Debian Lenny Xen-3.2.1 (please, no flames :))
> 
> The trouble is, when I go to create a new VM using the wizard, no
> install options are available because:
> 1) "Network install" is not available unless the connection is local, and
> 2) Local install media and  Network boot (PXE) are not available because
> of the following line in create.py (around line 340):
> is_pv = (self.capsguest.os_type == "xen")
> 
> I changed that line to:
> is_pv = False
> because Xen can do Full Virtualisation these days.  And I'm then able to
> create local CD install of a full virtualisation VM, which boots and
> works perfectly.
> 

This was a bug that should now be fixed upstream. I'd recommend you file a bug
with debian, with a link to the following commit:

http://hg.et.redhat.com/cgi-bin/hg-virt.cgi/applications/virt-manager--devel/rev/6374136c6247

> Three questions:
> 
> 1) Am I missing something, or is the is_pv definition just historical?

Nope, it serves a use in the code: if the host machine doesn't support
fullyvirt (possibly due to hardware restrictions), we need to limit the
install options.

> 2) What's wrong with doing a "Network install" when you're not local; I
> thought (please correct me if wrong) that a Network Install involved
> passing a URL to some sort of install repository; why would that need
> local access.

Because a network install has to fetch a boot kernel and initrd from the URL,
and we have no way to tell the remote machine to fetch these locations.

> 3) Why is it not possible to do a Local Install media or PXE boot with a
> para-virtualised guest?
> 

Because AFAIK xen PV guests on linux do not support CD or PXE booting.

HTH,
Cole