Re: [PATCH 2/2] kvm tools: Add virtio-9p

Sasha Levin
2011-05-26T15:30:08Z

On Thu, 2011-05-26 at 08:22 -0700, Venkateswararao Jujjuri wrote:
> On 05/26/2011 07:36 AM, Sasha Levin wrote:
> > On Thu, 2011-05-26 at 07:28 -0700, Venkateswararao Jujjuri wrote:
> >> Any progress on this? May I get more detailed instructions on how
> >> you did this trick? Basically booting on 9P/VirtIO.
> >>
> >> Thanks,
> >> JV
> >>
> > Ofcourse. This change didn't go into tools/kvm/ since we only support
> > the legacy 9p2000 protocol at the moment, which means that even though
> > we can boot - it's quite unusable to work with.
> >
> > The trick is pretty simple: You need to name your virtio transport
> > "/dev/root" (I think it's currently named "local" in qemu). Once it's
> > named this way, boot with the following kernel cmdline added:
> > "root=/dev/root rootflags=rw,trans=virtio,version=9p2000 rootfstype=9p
> > rw" (You should be able to change version to one of the 9p2000
> > extensions).
> Ah I guess you are making use of rootfstype.
> So in this setup basically the virtio transport you create
> is /dev/root instead of "kvm_9p" correct?

Yes, exactly.

> Also your dir will be / ?
>
> i.e Start KVM with '--virtio-9p /'. ?

It can be '/', but I'd suggest against trying to boot your hosts root
device within a guest (unless in RO mode maybe).

I've mounted a disk image to some directory on the host and booted that
directory for testing.

> > I've noticed that the transport *has* to be named "/dev/root", naming it
> > something else (and adjusting the "root=" parameter) doesn't seem to
> > work.
> >
> > Also, if it's named "/dev/root" I couldn't mount it as a simple
> > filesystem from within a guest - not as root.
> >
>

--

Sasha.