Xen users - Oct 2009 - switching kernel from dom0 to guest with pv-grub

anyone know of any type of instructions/howto for converting a quest from
using the dom0 kernel to something like pygrub or even better, pv-grub? Im
using CentOS as the dom0 and guest if that makes a diff.

 

Thanks,
Mark

 

 



_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

On Mon, Oct 19, 2009 at 02:17:52PM -0500, Mark Chaney
wrote:
>    anyone know of any type of instructions/howto for converting a quest
from
>    using the dom0 kernel to something like pygrub or even better, pv-grub?
Im
>    using CentOS as the dom0 and guest if that makes a diff.
> 
You could install a new guest with virt-install or virt-manager and
check the generated config file :)

virt-* installed centos/rhel/fedora PV guests use pygrub as a default.

Basicly it just means replacing the kernel/ramdisk/root/extra lines from
the cfgfile by bootloader= line.

-- Pasi


_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

I know how to do it from the config level, but im assuming I probably need
to install grub and download a xen kernel on the guest as well? They don’t
have any of that installed since they are currently using the kernel from
the dom0. Current config looks like this:

kernel = ''/XenConfigs/vmlinuz-vm2-xenU''
ramdisk = ''/XenConfigs/initrd.vm2.xenU.img''
memory = 2048
name = ''huffer''
vif = [ ''ip=xxx.xxx.xxx.xxx'' ]
address = ''xxx.xxx.xxx.xxx''
netmask = ''255.255.255.224''
disk = [''phy:/dev/VolGroup00/huffer_img,sda1,w'',
''phy:/dev/VolGroup00/huffer_swap,sda2,w'']
root = ''/dev/sda1 ro''

Just found out that the original guest you see above was created from
jailtime.org image, but with some additional config changes.

I am using a third party control panel for xen and I am trying to help them
figure out how to convert their images from using a dom0 type kernel setup
like this to being able to use pygrub or pv-grub. The problem is that really
needs one disk per filesystem, so it can mount and manipulate that
filesystem. Im hoping to find a way to convert their 20+ OS images into a
pv-grub compatible guest without having to recreate each guest from scratch.

I do see now that virt-install will allow you to specify additional disks,
though I am not 100% sure how the kickstart would know which disk is which,
plus im hoping I don’t have to go this route.

Hope my rambling makes sense. =)

-Mark


-----Original Message-----
From: xen-users-bounces@lists.xensource.com
[mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Pasi Kärkkäinen
Sent: Monday, October 19, 2009 3:52 PM
To: Mark Chaney
Cc: Xen-users@lists.xensource.com
Subject: Re: [Xen-users] switching kernel from dom0 to guest with pv-grub

On Mon, Oct 19, 2009 at 02:17:52PM -0500, Mark Chaney
wrote:
>    anyone know of any type of instructions/howto for converting a quest
from
>    using the dom0 kernel to something like pygrub or even better, pv-grub?
Im
>    using CentOS as the dom0 and guest if that makes a diff.
> 
You could install a new guest with virt-install or virt-manager and
check the generated config file :)

virt-* installed centos/rhel/fedora PV guests use pygrub as a default.

Basicly it just means replacing the kernel/ramdisk/root/extra lines from
the cfgfile by bootloader= line.

-- Pasi


_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users


_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

On Tue, Oct 20, 2009 at 4:15 AM, Mark Chaney <macscr@macscr.com>
wrote:
> I know how to do it from the config level, but im assuming I probably need
> to install grub
Not really. pygrub/pv-grub will simply read /boot/grub/menu.lst (which
you can create manually).
> and download a xen kernel on the guest as well?
Yes
> They don’t
> have any of that installed since they are currently using the kernel from
> the dom0.
for RHEL/Centos domU, you can simply run "yum install kernel-xen" from
within domU.
> The problem is that really
> needs one disk per filesystem, so it can mount and manipulate that
> filesystem.
It doesn''t matter. Using pygrub or dom0-located kernel does not change
your domU disk/filesystem layout.

Here''s my domU''s /boot/grub/menu.lst (relevant part only).
It''s
somewhat old, so just adjust to whatever kernel-xen version you have
installed.

default=0
timeout=5
title Red Hat Enterprise Linux Server (2.6.18-92.1.13.el5xen)
	root (hd0,0)
	kernel /boot/vmlinuz-2.6.18-92.1.13.el5xen ro root=/dev/hda1
	initrd /boot/initrd-2.6.18-92.1.13.el5xen.img

And here''s the relevant part of my domU''s config

disk = [ ''phy:/dev/rootVG/dns01lv,hda1,w'',
	''phy:/dev/rootVG/dns01swaplv,hda2,w'',
	]
bootloader="/usr/bin/pygrub"

The bootloader line replaces the previous kernel and ramdisk line.

-- 
Fajar

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users