RE: [Xen-users] Mixing architectures--64bit master, 32bit clients?

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Steven Timm
> Sent: 13 March 2007 18:09
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-users] Mixing architectures--64bit master, 
> 32bit clients?
> 
> 
> Has anyone successfully run the 64-bit Xen hypervisor (open source 
> version) with
> 32-bit xen virtual machines? If so, are there any pointers to a
> how-to of what to do, and things you should avoid?

This works fine in HVM (full virtualization) in any recent release of
Xen (e.g. 3.0.4 or 3.0.3).

Para-virtual model doesn't allow mix of hypervisor and guest modes, so
hypervisor and all guests (Dom0 and others) will have to be the same,
either 64-bit, 32-bit PAE or 32-bit non-PAE. This is being worked on in
xen-unstable, where you should be able to run 32-bit PAE on 64-bit
(32-bit non-PAE is a bit more complicated because the page-tables are
different between 32-bit non-PAE and 64-bit, whilst 32-bit PAE uses the
same page-table format). 

3.0.5 should have 32-bit PAE on 64-bit working (fingers crossed). 

Of course, for many purposes, 64-bit guests will run 32-bit apps
perfectly fine (just like it does on "bare-metal 64-bit systems"). There
are exceptions, but if you're not running particularly unusual setups in
your guests, you may want to try that as an approach. Some people,
reportedly, even install 32-bit distributions and just upgrade the
kernel itself to 64-bit with good results [although this is not what I
would recommend]. 

--
Mats
> 
> Thanks
> 
> Steve Timm
> 
> 
> -- 
> ------------------------------------------------------------------
> Steven C. Timm, Ph.D  (630) 840-8525
> timm@xxxxxxxx  http://home.fnal.gov/~timm/
> Fermilab Computing Division, Scientific Computing Facilities,
> Grid Facilities Department, FermiGrid Services Group, 
> Assistant Group Leader.
> 
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