Re: Question to recent xentools3 update

[Juergen Hannken-Illjes <hannken%eis.cs.tu-bs.de@localhost>]

On Fri, Mar 28, 2008 at 11:53:35AM +0100, Christoph Egger wrote:
> On Thursday 27 March 2008 19:55:15 Manuel Bouyer wrote:
> > On Thu, Mar 27, 2008 at 06:48:29PM +0100, Juergen Hannken-Illjes wrote:
> > > Pygrub opens the device once and the kernel doesn't allow a second open.
> > >
> > > For my setup with "disk = [ 'phy:/dev/raid0f,0x1,w' ]" I got an EBUSY
> > > when pygrub tried to open the block device.  I don't understand enough of
> > > Xen to say where this disk gets opened (xenbackendd, xbd device ...).
> >
> > The backend opens it before pygrub is started, yes.
> >
> > > > Isn't it possible to pass pygrub an edited version of the device name
> > > > or have pygrub edit it itself? If we were to use the non-raw device for
> > > > pygrub and the raw device for qemu-dm, would things work?
> > >
> > > If a Xen config with "disk = [ 'phy:/dev/rraid0f,0x1,w' ]" works and no
> > > other Xen component opens the corresponding block device this could work.
> > >  As my Xen machine is in production now, I cannot test it.
> >
> > I don't think it would work without a lot of work on the backend device
> > (I'm not even sure if it's possible). The backend assumes it was given a
> > block device, because it uses struct buf.
> 
> According to pkgsrc/sysutils/xentool3/patches/patch-dk, pygrub is now
> using a raw device  while the guests use the block device at the same time.
> So if I understand it correctly, it is possible to open /dev/raid0f
> and /dev/rraid0f at the same time?

Yes, only the block device cannot be open multiple times.  The raw device
allows concurrent opens.

-- 
Juergen Hannken-Illjes - hannken%eis.cs.tu-bs.de@localhost - TU Braunschweig 
(Germany)