RE: [Xen-devel] Migrate/Save of 32-bit domU Broken on Xen 3.1.2 64-bit dom0

["Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>]

Joshua --

Why do you need so much memory on dom0?  Are you thinking
that the total memory available to guests is limited to
what dom0 has?  Or are you running some memory-hungry
applications on dom0?

Note that 64-bit Xen + 32-bit Dom0 will support both 32-bit
and 64-bit domU's. (Oracle VM uses this configuration by
default on 64-bit capable machines.)  And save/restore/migration
has been tested to work for this (with the patch Kurt posted).

Dan

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx]On Behalf Of Joshua West
> Sent: Friday, January 18, 2008 4:06 PM
> To: Keir Fraser
> Cc: Kurt Hackel; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] Migrate/Save of 32-bit domU Broken 
> on Xen 3.1.2
> 64-bit dom0
> 
> 
> Dang, doesn't work in Xen 3.1.3-rc1 (like you said/expected), with or
> without Kurt's patches.
> 
> Hmm... I thought 32-bit paravirtualized domU's on 64-bit dom0's were
> supported in Xen 3.1.x?  Or am I mistaken?
> 
> Perhaps standard features such as start/shutdown/pause of 32-bit PV
> domU's on 64-bit dom0's are supported, but not the more advanced
> management features like save and migrate - and I was just 
> unclear from
> the beginning?
> 
> And of course... the final question that all developers hate... when
> s/could one _hope_ (not expect!) to see save/migrate functionality of
> 32-bit PV domU's on 64-bit dom0's? :-D
> 
> Our whole reason for moving to 64-bit dom0's was to utilize 32GB of
> memory, instead of the 16GB limitation on 32-bit PAE dom0's.  We can't
> convert all of our virtual machines (100+) to 64-bit linux as its too
> much work and some actually have to be 32-bit due to vendor supplied
> software (Oracle, Zimbra, etc).  I suppose we'll wait to move 
> to 64-bit
> until [live] migration is available, as its used quite 
> frequently in our
> machine rooms.
> 
> Thanks for all of your help Keir and Kurt.
> 
> Keir Fraser wrote:
> > Looking at the issues that need to be handled to support 
> this, it cannot be
> > expected to work.
> >
> >  -- Keir
> >
> > On 18/1/08 22:13, "Joshua West" <jwest@xxxxxxxxxxxx> wrote:
> >
> >
> >> Ahh.  Well, I'm building xen-3.1.3-rc1 right now and I'll 
> see how that goes.
> >>
> >> Keir, have you seen this issue before?  Where one cannot 
> xm save/migrate
> >> a 32-bit domU on a 64-bit dom0?  Or is this expected to 
> work and just
> >> doesn't go well for me?
> >>
> >> Keir Fraser wrote:
> >>
> >>> On 18/1/08 22:05, "Joshua West" <jwest@xxxxxxxxxxxx> wrote:
> >>>
> >>>
> >>>
> >>>> Just to make sure the patches aren't the cause of this new error
> >>>> message, I'm going to see what happens with Xen 
> 3.1.3-rc1 w/o patches.
> >>>>
> >>>> Kurt, Keir, everybody else... any ideas as to why "xm 
> save" (and thus
> >>>> "xm migrate") of 32-bit domU's does not work on 64-bit 
> dom0's?  Has
> >>>> anybody found this to be successful in the past?
> >>>>
> >>>>
> >>> The extent of the patches that Kurt posted indicate its 
> pretty unlikely to
> >>> work without considerable code modification. I guess 
> those patches aren't
> >>> quite fully baked yet, unfortunately, or haven't been 
> written with your
> >>> precise case in mind.
> >>>
> >>>  -- Keir
> >>>
> >>>
> >>>
> >>>
> >
> >
> >
> 
> 
> --
> Joshua West
> Systems Engineer
> Brandeis University
> http://www.brandeis.edu
> 
> 
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> http://lists.xensource.com/xen-devel
>


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