Xen users - Dec 2007 - Xen on RHEL 5.1 to para-virt Ubuntu Gusty

Hello once again ;)

  I''m looking for any information (tutorial / howto) to run Ubuntu
(Gutsy)
on a RHEL 5.1 XEN (2.6.18-53.1.4.el5xen)
  I tried to install the para-virt Ubuntu from a remote mounted cd-rom
available by HTTP like I did to install a paravirtualized RHEL 5.1
inside the RHEL Xen ;)

  Thanks by advance for any info!

   LMJ


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Le Wed, 19 Dec 2007 09:51:06 +0100 (CET),
"L.M.J." <linuxmasterjedi@free.fr> a écrit :
> Hello once again ;)
> 
>   I''m looking for any information (tutorial / howto) to run Ubuntu
(Gutsy)
> on a RHEL 5.1 XEN (2.6.18-53.1.4.el5xen)
>   I tried to install the para-virt Ubuntu from a remote mounted cd-rom
> available by HTTP like I did to install a paravirtualized RHEL 5.1
> inside the RHEL Xen ;)
> 
>   Thanks by advance for any info!
> 
>    LMJ
Hello,

  I didn''t had an reply, I''m trying again to see if I have
more luck.
   -> Howto para-virt Ubuntu Gusty 64 on RHEL 5.1 Xen 64

  Thanks by advance!


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>   I''m looking for any information (tutorial / howto) to run Ubuntu
(Gutsy)
> on a RHEL 5.1 XEN (2.6.18-53.1.4.el5xen)
>   I tried to install the para-virt Ubuntu from a remote mounted cd-rom
> available by HTTP like I did to install a paravirtualized RHEL 5.1
> inside the RHEL Xen ;)
Well, there are various ways you can tackle this.

I typically use an HVM install (full virtualisation) of Ubuntu onto RHEL 
initially, since this is convenient and well supported by the virt-manager 
tool.  I then convert this into a paravirtualised install if I want at a 
later date.  This is an approach I quite like.

Or, there''s a tool called "debootstrap" that will create a
basic debian (or
ubuntu) filesystem in a directory.  You can put this onto a virtual disk by 
simply mounting the filesystem on that disk into dom0 (e.g. using the lomount 
utility from qemu, which is supplied with Xen) and then running debootstap 
against that directory.

You ought to be able to chroot into that filesystem subsequently and use 
apt-get to install a Xen-aware domU kernel and initrd.  When you''re
done with
editing the filesystem in dom0, umount it so that the guest can use it 
safely.

Finally in dom0 you can create a config file to boot that virtual disk and use 
pygrub to find and load the kernel from the guest''s filesystem.

Hopefully one of those methods will suit you!  Let us know if you need more 
help.

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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>>   I''m looking for any information (tutorial / howto) to run
Ubuntu
>> (Gutsy)
>> on a RHEL 5.1 XEN (2.6.18-53.1.4.el5xen)
>>   I tried to install the para-virt Ubuntu from a remote mounted cd-rom
>> available by HTTP like I did to install a paravirtualized RHEL 5.1
>> inside the RHEL Xen ;)
>
> Well, there are various ways you can tackle this.
>
> I typically use an HVM install (full virtualisation) of Ubuntu onto RHEL
> initially, since this is convenient and well supported by the virt-manager
> tool.  I then convert this into a paravirtualised install if I want at a
> later date.  This is an approach I quite like.
Sound nice because I already have a full virtualized Ubuntu on RHEL at the
moment. How did you switch to paravirt? Do you just install the Ubuntu Xen
kernel and reboot?
> Or, there''s a tool called "debootstrap" that will create
a basic debian
> (or ubuntu) filesystem in a directory.  You can put this onto a virtual
> disk by simply mounting the filesystem on that disk into dom0 (e.g. using
> the lomount utility from qemu, which is supplied with Xen) and then
> running debootstap against that directory.
>
> You ought to be able to chroot into that filesystem subsequently and use
> apt-get to install a Xen-aware domU kernel and initrd.  When
you''re done
> with editing the filesystem in dom0, umount it so that the guest can use
> it safely.
>
> Finally in dom0 you can create a config file to boot that virtual disk and
> use pygrub to find and load the kernel from the guest''s
filesystem.
>
> Hopefully one of those methods will suit you!  Let us know if you need
> more help.
>
> Cheers,
> Mark
Allright, in a second time, I will check out the debootstrap method,
I''m
already aware about it because I tried Xen on Ubuntu''Dom0 ;) I just
have
to install debootstrap on RHEL : I will test this at the end of the week.
Thanks & Merry christmas to everybody ;)


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>>>   I''m looking for any information (tutorial / howto) to
run Ubuntu
>>> (Gutsy)
>>> on a RHEL 5.1 XEN (2.6.18-53.1.4.el5xen)
>>>   I tried to install the para-virt Ubuntu from a remote mounted
cd-rom
>>> available by HTTP like I did to install a paravirtualized RHEL 5.1
>>> inside the RHEL Xen ;)
>>
>> Well, there are various ways you can tackle this.
>>
>> I typically use an HVM install (full virtualisation) of Ubuntu onto
RHEL
>> initially, since this is convenient and well supported by the
>> virt-manager
>> tool.  I then convert this into a paravirtualised install if I want at
a
>> later date.  This is an approach I quite like.
>
> Sound nice because I already have a full virtualized Ubuntu on RHEL at the
> moment. How did you switch to paravirt? Do you just install the Ubuntu Xen
> kernel and reboot?
Anyone could help me out on this question please? How switch from fullvirt
to paravirt like Mark seems to do.

 Thanks!

>> Or, there''s a tool called "debootstrap" that will
create a basic debian
>> (or ubuntu) filesystem in a directory.  You can put this onto a virtual
>> disk by simply mounting the filesystem on that disk into dom0 (e.g.
>> using
>> the lomount utility from qemu, which is supplied with Xen) and then
>> running debootstap against that directory.
>>
>> You ought to be able to chroot into that filesystem subsequently and
use
>> apt-get to install a Xen-aware domU kernel and initrd.  When
you''re done
>> with editing the filesystem in dom0, umount it so that the guest can
use
>> it safely.
>>
>> Finally in dom0 you can create a config file to boot that virtual disk
>> and
>> use pygrub to find and load the kernel from the guest''s
filesystem.
>>
>> Hopefully one of those methods will suit you!  Let us know if you need
>> more help.
>>
>> Cheers,
>> Mark
>
> Allright, in a second time, I will check out the debootstrap method,
I''m
> already aware about it because I tried Xen on Ubuntu''Dom0 ;) I
just have
> to install debootstrap on RHEL : I will test this at the end of the week.
> Thanks & Merry christmas to everybody ;)
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>
>


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> > I typically use an HVM install (full virtualisation) of Ubuntu onto
RHEL
> > initially, since this is convenient and well supported by the
> > virt-manager tool.  I then convert this into a paravirtualised install
if
> > I want at a later date.  This is an approach I quite like.
>
> Sound nice because I already have a full virtualized Ubuntu on RHEL at the
> moment. How did you switch to paravirt? Do you just install the Ubuntu Xen
> kernel and reboot?
Almost that, yeah.

Installed the Ubuntu Xen kernel, then I had to shut down and modify the domain 
config.  I''m using flat file configs and with these you need to
properly
shutdown and recreate the domain in order for config file changes to have an 
effect.

The config modifications change the builder argument to "linux" rather
than
hvm and deleted the "kernel=" line because it was no longer needed.  I
may
also have added bootloader="/usr/bin/pygrub" but I don''t
think this is
actually necessary.

That''s all i can think of for the moment, but I''ve probably
missed something
or other.  It was fairly simple all the same though.

I''ve occasionally pondered modifying the Xen tools to make it possible
(and
easy) to "dual boot" between PV and HVM modes.  Do you think this
would be
useful?
> Allright, in a second time, I will check out the debootstrap method,
I''m
> already aware about it because I tried Xen on Ubuntu''Dom0 ;) I
just have
> to install debootstrap on RHEL : I will test this at the end of the week.
> Thanks & Merry christmas to everybody ;)
debootstrap compiles and runs on non-Debian systems so this should work for 
you.  It probably won''t configure things quite as nicely / completely
as
using the full Ubuntu installer and then converting would have done but it 
ought to get to an install in the end (fingers crossed) and it is quite 
convenient.

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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Mark Williamson wrote:
>> Sound nice because I already have a full virtualized Ubuntu on RHEL at
the
>> moment. How did you switch to paravirt? Do you just install the Ubuntu
Xen
>> kernel and reboot?
> 
> Almost that, yeah.
> ...
> I''ve occasionally pondered modifying the Xen tools to make it
possible (and
> easy) to "dual boot" between PV and HVM modes.  Do you think this
would be
> useful?
*very* useful; I''ve had no end of trouble booting the same image in
both
PV and HVM modes, and I''ve given up. a manual change is hard enough -
on
F8, after using virt-install, I have to change fstab, mess with SELinux, 
modprobe.conf, inittab, and so on, get a new initrd, label (and 
enable?!) the swap partition, and so on. Even after that lot I don''t 
think a virt-install-created PV image will boot up as HVM. I can''t 
understand why this lot should be necessary. You end up with a 
non-standard distribution which is difficult to understand or maintain 
(and apps running in the DomU would have to *really* dumb if they can''t
figure out that they''re running virtualised).

 From the user perspective, this would be a great thing to have. It 
would be nice to start with a stock install (perhaps one you dual-booted 
from previously), boot it as an HVM DomU, and then gradually 
paravirtualise it if/when necessary, changing back if you get it wrong. 
Ideally, all the necessary changes should be hidden in the kernel, where 
the user can''t see them. I think this would probably take out 90% of
the
complexity of using Xen for new users, for what should be a fairly 
modest effort.

Evan

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