Fwd: FreeBSD 11.1 xen trying to create linux domU instance

[Roger Pau Monné]

On Mon, Aug 21, 2017 at 10:56:33AM -0700, James E. Pace wrote:
> Hi,
> 
> I have a couple questions about running xen with FreeBSD 11.1 (amd64) as
> Dom0.  I am pretty new to this whole concept, so it is very likely I am not
> understanding something.
> 
> First, each time I boot the (physical) system, I have to tell the FreeBSD
> boot loader to turn on xen.  (That is, hit 6 to set options, then 7 to
> enable xen, then 1 to return to the main menu, then 1 to boot).  Is there a
> way to make this the default behavior?

Yes, you need to add the following to /boot/loader.conf:

xen_kernel="/boot/xen"

You can also set xen_cmdline if you want/need to pass any extra
command line arguments to Xen.

> 
> Second, I want to create a Linux domU instance.  I have been successful in
> getting a FreeBSD 11.1 domU running, but changing that config file to use a
> Linux CD doesn't boot (or crashes on boot?).  I've tried a couple linux
> distributions with similar results.
> 
> Here's my xen config file:
> 
> builder = "hvm"
> name = "xen-ubuntu"
> memory = 1024
> vcpus = 1
> vif = [ 'bridge=bridge0' ]
> disk = [
>     '/dev/zvol/pool/xen-ubuntu,,hda,rw',
                                 ^ try adding raw here.
>     '/pool/Downloads/ubuntu-15.10-desktop-amd64.iso,raw,hdc:cdrom,r'
>     ]
> vnc = 1
> vnclisten = "0.0.0.0"
> serial = "pty"
> 
> I created the backing filesystem with:
> zfs create -V20G -o volmode=dev pool/xen-ubuntu
> 
> "xl create foo.cfg" returns fine, and "xl list" shows the instance, but the
> running instance (via vncviewer) eventually spits out:
> 
> 4.130084] vbd vbd-5632: 19 xenbus_dev_probe on device/vbd/5632
> 4.130956] vbd vbd-5632: failed to write error node for device
> device/vbd/5632 (19 xenbus_dev_probe on device/vbd/5632)

It seems like the disk is failing to attach AFAICT. Try adding raw as
suggested above.

> 
> I suspect the linux kernel isn't booting because it can't figure out
> something about the zfs volume.  But I'm not sure, and I don't know how to
> work around it.
> 
> 
> Third, on my DomU FreeBSD guest, I'm trying to set up X / Gnome3.  The
> mouse pointer and the little dot are far apart; that is, the mouse isn't
> tracking my movements well.  I found several suggestions to add
> "usbdevice=tablet" to the config file, but that caused it to not respond to
> my mouse at all.  Suggestions?

This should be:

usbdevice=['tablet']

Roger.