Re: [Xen-users] Converting the full-virtualization to para-virtualize

Mark Williamson
2007-12-02T18:14:08Z

> I got a question here. Can I install a full-virtualized fedora 7 as dom0
> then convert it into para-virtualized?
>
> It''s because I had tried faced so many errors when installing the
> para-virtualized  fedora7 with the nfs server.

I assume you meant installing a paravirtualised F7 as domU, not dom0?  (if it
were dom0 you could just use the F7 installer and specify that you wanted
virtualisation).

Converting it in this way should be fairly straightforward.  Use yum in your
domU and get it to install the F7 Xen-enabled guest kernel (don''t
install the
Xen package itself, you don''t want the hypervisor or tools).  This may
configure a guest entry in grub automatically, or you may have to add one for
your guest kernel and initrd manually - I''ve not used F7 much, so
I''m not
sure.  Then you need to change the configuration for the domain to be
paravirtualised...

I assume you''re using virt-manager?  I don''t know if the
version in F7 stores
config files in /etc/xen/?  In which case you could just copy / alter those
config files to conform to a PV guest.  If not, I understand you can
use "virsh" to dump the config file into XML form, then modify it,
then
reload that file to change the config used for the domain.

To convert it to PV you''ll basically want to remove all the HVM-isms
(e.g.
stuff like the ioemu devices, the hvmloader, the builder, etc may need to be
changed) and add in the relevant PV-isms (e.g. different syntax for
describing virtual framebuffer, "linux" builder, pygrub bootloader,
device
names changed to xvd*).

Then if you boot the domain with xm create -c you ought to see the pygrub
screen appear; select the Xen-enabled grub entry that you installed.  It
should boot (fingers crossed).

If you keep a copy of the original HVM config you should be able to switch
between the two fairly easily for debugging purposes.  If you installed the
guest to use partitions, not LVM, then it''s trivial to mount the
guest''s
filesystem from dom0 to make tweaks.

Cheers,
Mark

--
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