paravirtualized 32-bit on 64-bit host?

[Jose R R]

On 3/18/08, Furnish, Trever G <TGFurnish at herffjones.com> wrote:
>
> > -----Original Message-----
> > From: redhat-list-bounces at redhat.com
> > [mailto:redhat-list-bounces at redhat.com] On Behalf Of Jose R R
> > Sent: Friday, March 14, 2008 12:43 PM
> > To: General Red Hat Linux discussion list
> > Subject: Re: paravirtualized 32-bit on 64-bit host?
> >
> > On 3/7/08, Furnish, Trever G <TGFurnish at herffjones.com> wrote:
> > >
> > > Anyone managed to get a paravirtualized 32-bit guest working on a
> > > 64-bit redhat host?  The RHEL5.1 release notes claim
> > there's preview
> > > support for it.  If by "technology preview" they mean, "We tried it
> > > and it didn't work", then yeah, I guess there's support.  But I'm
> > > having no luck. :-(
> > >
> > >
> > >
> http://www.redhat.com/docs/manuals/enterprise/RHEL-5-manual/release-no
> > > te
> > > s/RELEASE-NOTES-U1-x86_64-en.html
> > >
> > > Anyone else fairing better?
> > >
> > > --
> > > Trever
> > >
> >
> > Well last year I installed a 32-bit WinXP instance under
> > 64-bit OpenSuSE host implementation of Xen.
> > Of course, proprietary technology is not actually
> > paravirtualized, but rather fully virutalized with the help
> > of the (AMD CPU in my specific case) hardware extensions.
> > You can find an overview of what I did, if interested of course, at:
> > http://www.metztli-it.com/blog/index.php?blog=4&title=open-sou
> > rce-on-sun-microsystems-sun-ultr-20&more=1&c=1&tb=1&pb=1
> >
> >
> > Regards,
> >
> > Jose R Rodriguez
> > http://www.metztli-it.com
>
>
> Thanks, Jose.  I was hoping to avoid full virtualization due to the
> reported performance impacts, but perhaps that'll just have to wait.
> And you were the only one who even responded -- much appreciated!
>
>
>
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 If you read my evaluation of the entry
level Sun machine, you were aware that
my initial intention was to install the thin layer of the XenSource
Xen hypervisor implementation on the "bare metal" of the entry level Sun
workstation.  That was back when XenSource released
XenExpress, XenServer (Windows VMs only), and
XenEnterprise, version releases 3.2.x on 32-bit architecture only.


Well, XenSource released an upgrade implementation of the
Xen hypervisor in the summer of 2007,
XenServer 4, that runs natively in 64-bit
architecture, supporting both 32-bit full- and
paravirtualized guests as well as 64-bit guests –all mixed within the same
XenServer 64-bit mode environment.

If you were to install XenServer 4 in your 64-bit
server(s), you could control your susequently
created (or migrated and/or converted from a
physical instance) full- or paravirtualized
virtual machine guests  from an Windows
(client) machine hosting XenSource's administration
console (also called XenCenter).


Note that you would have (at least) three options, depending on which
32-bit RH kernel you

are attempting to run paravirtualized in the XenSource 64-bit environment.


The first option is that the paravirtualized 32-bit
kernel might be already available, either
from Red Hat itself, or from a third party.   For instance,
XenSource has shipped some modified Linux kernels with its products
since (at least) version 3.x.


Second option is to install directly from the Linux
distribution media into a 32-bit guest vm.
 You will only need to have hardware
assisted support for the installation phase.  Afterwards, XenServer can
"Xenify" the kernel, effectively converting it into
paravirtualized mode so that it can be run closer to "bare metal
installation" performance level.


The third option is that certain RHEL, like 4.1 and 4.4, will be
paravirtualized on the
fly if you first place the installation media contents
into a network installation source repository.   Subsequently, you would use
the administration console (or XenCenter) to
install from that repository directly into your virtual machine server(s)'
vm instance.


Ok, almost forgot.  If you currently are running
your RH distro in an physical box, you
could use an utility (P2V) to paravirtualize
an existing operating system physical instance
into a virtual machine instance.  You could save the image and subsequently
transfer that into your 64-bit XenServer environment.


The unifying theme in RH, Novell, Oracle, and Sun, (and Debian and others)
is the open source Xen hypervisor.  It
is the implementation of the former that is the differentiator in the
competing vendor/free offerings.

Citrix acquired XenSource but you can still find information and download a
limited Express starter edition, as well as a trial of the enterprise class
product from < http://www.xensource.com >

By the way, VirtualIron (< http://www.virtualiron.com >) has also an 64-bit
implementation of Xen that may suit your purpose.  Notwithstanding, we are a
Citrix/XenSource partner and thus more familiar with the product.

Additional sources for your perusing:

< http://lists.xensource.com/archives/html/xen-users/2007-07/msg00838.html >

< http://wiki.xensource.com/xenwiki/HVM_Compatible_Processors >

Best of luck!


Jose R Rodriguez

http://www.metztli-it.com