Re: [Xen-users] Match between Dom0 and DomU PV

["Fajar A. Nugraha" <fajar@xxxxxxxxx>]

On Wed, May 27, 2009 at 12:47 AM, Chris 'Xenon' Hanson
<xenon@xxxxxxxxxxxxxx> wrote:
> Here's my real question: how much match-up must there be between the kernel 
> of the Dom0
> and of the PV DomU?

Newer kernels and hypervisors should be able to work even when their
version are not exact match, provided that:
- they are new enough (Xen >= 3.1 should be enough)
- they are architecturally compatible (64bit hypervisor can work with
64bit and 32bit PAE kernel, but 32bit hypervisor can only work with
32bit kernel)

> Here, I have a Debian 5 x64 (2.6.26-2-xen-amd64) Dom0 and Ubuntu 8.04
> x86-32 (2.6.24-23-xen) DomU. It seems to be known that that 2.6.24-23-xen is 
> the problem,
> and 2.6.28.8 is recommended.

Really? by 2.6.28.8 I assume you mean pv_ops kernel. It works, but not
all features of -xen kernel is available on pv_ops kernel yet. See
http://wiki.xensource.com/xenwiki/XenParavirtOps

Have you tried the suggestions on the previous thread? from my
experience Debian's kernel (or RHEL's kernel, if you're feeling
adventurous) works quite nicely as domU kernel for Ubuntu. Plus you
don't have to compile anything.

>
>  Before I go recompile my DomU, I'm curious how closely they have to match? 
> Like, if I
> have a newer Xen version in the DomU or the Dom0, do they get along ok?

They should work OK. Some of the combinations I have on my setup :
- Xen 3.3.1 and Xen 3.3.4 hypervisor, kernel from RHEL (xen 3.1.2+) as
both dom0 and domU, Debian kernel as domU.
- Opensolaris (Xen 3.1.4) hypervisor and dom0, RHEL (xen 3.1.2+) and
Debian (xen 3.2.1?) kernel as domU.

All of them are 64bit.

>
>  I also have little experience with x64 Linux -- I presume I can't just boot 
> my Ubuntu
> 8.04 (x86-32) DomU using the 2.6.26-2-xen-amd64 kernel my Dom0 uses, because 
> that DomU is
> an entirely 32-bit Ubuntu, and the Dom0 is a 64-bit Debian kernel, right?

It should work, but you might have some problems with kernel
module-userland interaction (e.g. using iptables).
Try http://packages.debian.org/lenny/linux-image-2.6.26-2-xen-686

-- 
Fajar

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