On 17/01/08 02:45, John Summerfield wrote:
> Jan Iven wrote:
..
>> SL4 can then run as a domU, with some caveats (cannot mix 32/64 bit
>>  doms).
> 
> I'm not sure about that. I run 64-bit Fedora 8 on Intel, and run
> several 32-bit guests.

Sorry - I was unclear and perhaps wrong.  As stated on
http://www.linuxtopia.org/online_books/centos5/centos_5_xen_virtualization/centos5_ch-virt-hw-support.html

> With Red Hat Virtualization, 32-bit hosts runs only 32-bit
> paravirtual guests. 64-bit hosts runs only 64-bit paravirtual guests.
> And a 64-bit full virtualization host runs 32-bit, 32-bit PAE, or
> 64-bit guests. A 32-bit full virtualization host runs both PAE and
> non-PAE full virtualization guests.

This could have changed with 5.1 -  Red Hat claims on
http://www.europe.redhat.com/rhel/virtualization/ that 5.1 now has

> # The ability to run 32-bit para-virtualized guests on x86-64 systems running in 64-bit mode.
(I guess they are talking about the dom0 here)

DELL seems to agree that mixing may be problematic:
http://www.dell.com/downloads/global/power/ps4q07-20070547-DeLaRosa.pdf

> Note: Red Hat virtualization only fully supports
> matching host/guest architectures—that
> is, environments in which both the host and
> guest OS are either 32-bit or 64-bit operating
> systems. Running a 32-bit guest OS on a 64-bit
> host OS is supported only with paravirtualization,
> and running a 64-bit guest OS on a 32-bit
> host OS is not supported.

I guess all this together shows that "there may be issues", which is 
what I tried to convey..

Regards
jan