Xen in Hardy

[Aurélien Naldi]

On Wed, Apr 2, 2008 at 11:43 PM, Leandro Pereira de Lima e Silva
<leandro at limaesilva.com.br> wrote:
> Sander,
>
> That's what I did:
> - I was trying to create a virtual machine with hardy on it (hardy on the
> host too) using xen-create-image.
> - xen-tools isn't coming with hooks for installing hardy (I've already
> filled a bug report about that), so I tried symlinking hardy.d to edgy.d
> just like the symlinks from feisty.d and gutsy.d.
>  - Runned: xen-create-image --force --fs ext3 --image-dev
> /dev/group/volume_root --memory 512 --passwd --swap-dev
> /dev/group/volume_swap --dist hardy --mirror
> http://br.archive.ubuntu.com/ubuntu --gateway gateway_ip_addr --ip ip_addr
> --netmask netmask_addr --hostname hostname_addr, where "group/volume_root",
> "group/volume_swap", "gateway_ip_addr", "ip_addr", "netmask_addr",
> "hostname_addr" are actually other things that I've changed to get some
> privacy.
>  - Tried to boot, but initramfs can't find the root.
> - Fixed a few things on the configuration file generated by xen-create-image
> (tried different combinations, this is how it ended):
>   - Add "root        = '/dev/sda2 ro'" after the memory line.
>    - Fixed the disk section that just contained "',sda1,w'," inside of it,
> at the end it became:
>       disk        = [ 'phy:group/volume_swap,sda1,w',
> 'phy:group/volume_root,sda2,w' ]
>  - Add "xenblk" to /etc/initramfs-tools/modules and recreated the initrd
> file. (the same as the above item, what seemd to work after a few
> tentatives)
> - Runned xm create -c hostname_addr
> - Machine starts to boot and hangs at:
>   * Running local boot scripts (/etc/rc.local)                            [
> OK ]
>
> - Switched to gutsy (in xen-create-image), thinking that maybe it hangs
> because of some new hook needed for hardy.
> - Got the same problem that I had with hardy.

Your guest probably doesn't hang, it just doesn't show the login
prompt. You will get one by adding the following to your
/etx/xen/guest-name.cfg:

extra = "console=tty"


Incidently, I have been playing just yesterday with xen in hardy and
encountered the same problems.
The next one for me is that the guest can't connect to the net, even
if an eth0 shows up. The problem seems to be related to the new kernel
in hardy as the very same host using gutsy kernel works just fine.

More info on https://bugs.launchpad.net/ubuntu/+source/xen-3.2/+bug/204010

I would like to take the occasion to ask about the future of xen in
ubuntu. A while ago a switch to kvm was announced. I would like to
know if xen will still be supported or if it will be deprecated at
some point.
The nice thing with kvm is its simplicity when running unmodified
guests, but it is much slower than xen when running "xen-enabled"
guests. Xen has a number of other advantages:
- the xen-create-image scripts make building new guests with xen much
easier and faster than with kvm!
- xen can use real devices easilly, I'm not even sure that kvm can (it
requires full disk image, doesn't it ?)

as a result, xen is so much easier to use and efficient for my use
case (always running a few systems, without graphical interface).

 I see few options for xen in hardy
* fully supported, which requires to fix the bugs discussed in this
thread (missing hardy hooks, missing xenblk in initramfs/kernel and
broken xennet in the latest kernel)
* supported, which requires a bit less work (i.e. reverting to gutsy
kernel to fix the xennet bug)
* deprecated, which would be a bad regression if kvm doesn't get a LOT
of attention (which is probably not doable in time)

is the plan one of these options or an alternate one ? And then what
is the plan in the long run ? The fedora guys seem to be working
toward integrating as much of the huge and dirty xen patch in the
vanilla kernel. If they succed the state of xen in every distrtib
would be greatly improved IMHO. Is canonical able/willing to help this
effort ?

Sorry for the long worries/ranting, I hope it doesn't feel harsh for
the people working on xen in ubuntu as it really doesn't intend to:
thanks for your work so far, I just would like to get more hints about
the future and didn't find any recent  "official" discussion about
this.

Regards.

-- 
Aurélien Naldi