[Xen-users] Re: Perfect setup for Xen hypervisor 64bits, dom0 32bits and domUs 32 or 64 bits on a Debian Lenny, at last!

[Thiago Camargo Martins Cordeiro <thiagocmartinsc@xxxxxxxxx>]

Hi!

 Every day I learn a bit more about the Xen, I think... WTF! This software is awesome!

 My new Debian Lenny dom0 32bits on top of a Xen Hypervisor 64bits and two guests:

lenny01:~# uname -a
Linux lenny01 2.6.26-1-xen-686 #1 SMP Wed Nov 26 23:50:09 UTC 2008 i686 GNU/Linux

# Guest01 is a Debian Lenny created with xen-tools, but  with my
# self compiled Linux 2.6.27.9 from kernel.org (32bits domU)

lenny01:~# xm console guest01
guest01:~# uname -a
Linux guest01 2.6.27.9-tcmc-8.12-guestxen-1 #1 SMP Thu Dec 18 00:43:41 UTC 2008 i686 GNU/Linux

# My Ubuntu Intrepid Ibex 8.10 Server (NOT virtual - aka JeOS) 64bits domU.
# Guest02 is a Intrepid manually converted from a HVM.
# I was wondering that I can use the SAME kernel of the HVM in a PVM! Just changing dom0 configurarion file...
# Never had able to do that before! Amazing!

lenny01:/mnt# xm console guest02
root@guest02:~# uname -a
Linux guest02 2.6.27-7-server #1 SMP Fri Oct 24 07:20:47 UTC 2008 x86_64 GNU/Linux
^^^ This is a PVM domain! With default kernel from Ubuntu!   O_O

 I'm sure it's time to use PV-Grub...     =)

 I have a little question here:

 To get this Intrepid 64bits domU, I first install it from ISO using HVM domain, but since Intrepid kernel has a Xen support build into it,

how to boot the ISO image in a PVH domain

 In this setup, we can't use xen-tools com dom0 32bits to create a 64bits domU, xen-tools do some ugly chroots...

Regards,
Thiago

2008/12/17 Thiago Camargo Martins Cordeiro <thiagocmartinsc@xxxxxxxxx>

Dear friends!

 I must share this setup!  

 I was wondering to setup a really nice dom0, more like Citrix XenServer does...

 My server have 32G of RAM.

 First, I do NOT want a dom0 64bits because it will have only ~512M of RAM (dom0_mem=512M at GRUB), and has we know, it's not a good idea to have a 64bits system with low memory.

 Second, kernel 2.6.26 used by Debian doesn't have a good support for 64bits under Xen, only 2.6.27 have this support implemented in mainline Linux.

 But how to do this? I mean, how can I have a 32bits dom0 with a 64bits Hypervisor if Debian doesn't have 64bits packages on a 32bits systems? It's pretty simple!

1) Get the latest Debian Lenny i386 at http://www.debian.org/devel/debian-installer/ ;

2) ONLY Install a standard system at tasksel;

3) Optional: add contrib and non-free components to your sources.list;

4) Install Xen 32bits first: aptitude install xen-linux-system-2.6.26-1-xen-686;

5) Configure your dom0 memory in GRUB and do update-grub;

6) Configure "dom0-min-mem" and "dom0-min-mem" according to your environment;

7) Reboot into your new 32bits Hypervisor.


 Your system will be like this:

lenny01:~# uname -a
Linux lenny01 2.6.26-1-xen-686 #1 SMP Wed Nov 26 23:50:09 UTC 2008 i686 GNU/Linux

lenny01:~# xm info | grep xen_caps
xen_caps               : xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p

 But I know my new HP can run 64bits virtual machines, so, here we goes:

1) Log as root in your dom0;

2) Get new 64bits Hypervisor from Debian amd64 tree at http://packages.debian.org/lenny/amd64/xen-hypervisor-3.2-1-amd64/download ;
wget http://ftp.br.debian.org/debian/pool/main/x/xen-3/xen-hypervisor-3.2-1-amd64_3.2.1-2_amd64.deb

3) Install your new Hypevisor with dpkg:
lenny01:~# dpkg --force-all -i xen-hypervisor-3.2-1-amd64_3.2.1-2_amd64.deb

4) Verify your GRUB menu;

5) Reboot into your new 64bits Hypervisor with a 32bits dom0.

 You will get two Xen boot options in your next boot, one for each arch.

 Now I have:

lenny01:~# grep dom0_mem /boot/grub/menu.lst
# xenhopt=dom0_mem=512M
kernel          /xen-3.2-1-amd64.gz dom0_mem=512M
kernel          /xen-3.2-1-i386.gz dom0_mem=512M

lenny01:~# uname -a
Linux lenny01 2.6.26-1-xen-686 #1 SMP Wed Nov 26 23:50:09 UTC 2008 i686 GNU/Linux

lenny01:~# xm info | grep xen_caps
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64

 If someone knows a better procedure to got this running, I will appreciate!
 I don't know it this will bring me unexplained problems, anyone knows if this is Ok?

 That't it! Xen is so CoOL!

Best Regards,
Thiago

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