John Summerfield wrote:
> Jan Iven wrote:
>> 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)
> 
> Well, I did mention my experience is on F8:-) I've only one system with
> hardware virtualisation, and its first level OS is Fedora 8.
> 
> I use it to answer questions such as "Can I take this windows system run
>   it on different hardware without it barfing because it's become
> unactivated?" and to similarly play with Windows domains.
> 
> I seem to have an inordinate array of problems:-( Fortunately, Fedora
> has two virtualisation technologies, there's also KVM, and sometimes one
> works when the other does not.
> 

Just so you know, because this was discussed on Fermi's mailling list.

The xen in SL 5.1 is 3.0.3, the same as RedHat's.

RedHat's original release announcement said that you can run 32 bit 
paravirtualized guests on 64 bit xen hosts.
RedHat's engineers then quickly said "No it doesn't, don't do it.  We need to 
change the announcement."

Last time I checked, RedHat hadn't changed the announcement, so we ran some 
testshere at Fermi.

On SL5 is technically possible to get a 32 bit guest paravirtulized guest 
running on a 64 bit host.  But don't do it.  It will crash.  The longest we 
ever got one to stay  up was 5 minutes.  Most won't even fully boot before 
crashing.

We had some users that needed 32 bit guests on 64 bit hosts, so they updated to 
the latest stable xen (3.1.x I believe) and they were able to do it, and it 
seemed to be stable.

Fedora 8 (and possibly 7) has the latest xen in it, so it most likely that they 
have the version that will do 32 bit guests on 64 bit hosts.

Troy
-- 
__________________________________________________
Troy Dawson  [log in to unmask]  (630)840-6468
Fermilab  ComputingDivision/LCSI/CSI DSS Group
__________________________________________________