Re: [Xen-devel] Hvm Guest Image

[Mats Petersson <mats@xxxxxxxxxxxxxxxxx>]

At 09:34 17/07/2007, Xen Xen wrote:
> Well the problem is that i want to insert modules compiled from the 
> unmodified drivers into the hvm guest.
> But there is a  problem  with the module version of both the hvm 
> guests kernel and the dom0 kernel where i am compiling them. So i 
> would need the same kernel running as dom0 to run as hvm guest. Any 
> way i can do it??
If you want to run the same kernel, then you shouldn't be using 
HVM-mode [there's no advantage in doing that if your goal isn't to 
run a "standard distro as it comes on the media"].
If you still want to run HVM, you need to have two different kernels 
+ related modules, as the modules in Dom0 are compiled with the 
modified header files (and some have the source modified too) to 
allow them to behave nicely in a para-virtual environment (e.g. 
calling hypercalls to the Xen kernel when a standard kernel "just 
gets on with it").
There is work on coming up with a "para-virt-ops" kernel, which will 
"know" whether it's running on a hypervisor or not, and "adjust" it's 
internal functionality to suit the environment it's run in, but 
that's not ready for use yet [There was a 44-patch-set sent in today 
to this mailing list for possible inclusion in the Linux-mainstream kernel].
By the way, the best way to build unmodified drivers is to add the 
source-code to your installed guest-kernel, and build them. It should 
work reasonably well even with earlier versions of the kernel - as 
long as it's 2.6 and reasonably resent - 2.6.9 may not be new enough, 
but something a few steppings newer should be fine.
Alternatively, take the linux-2.6.18.tar.bz2 that is downloaded 
during the build, untar it outside the xen-tree, add the unmodified 
drivers and build that.
--
Mats


> On 7/17/07, Mats Petersson 
> <<mailto:mats@xxxxxxxxxxxxxxxxx>mats@xxxxxxxxxxxxxxxxx> wrote:
> At 08:56 17/07/2007, Xen Xen wrote:
> >the xen source directory that i downloaded has a ref-linux-2.6.18 directory.
> >Is that the unmodified linux that i can use to install a hvm guest??
>
> I don't know if the ref-linux-2.6.18 is suitable to build - it's
> there as a "base" for the modifications for para-virtual Linux that
> you need at least for Dom0.
>
> Well, the general way to use HVM is to install from a CDROM/DVD (or
> ISO-file image instead of a CD/DVD) with a complete distro of Linux
> (RedHat, SuSE, Debian, etc).
>
> Where do you get the rest of your Linux distro from? Doesn't that
> come with a kernel that you can use? That would be my suggestion.
>
> --
> Mats
>
>
> >On 7/17/07, Mats Petersson
> ><<mailto:mats@xxxxxxxxxxxxxxxxx><mailto:mats@xxxxxxxxxxxxxxxxx>mats 
> @planetcatfish.com> wrote:
> >At 06:08 17/07/2007, you wrote:
> >
> > >I downloaded the xen source from the xen site did a make world and
> > >make install to get the 2.6.16.33-xen kernel.
> > >I made a initrd for the same and booted into it.
> > >I want to now set up a hvm guest with the same image( 2.6.16.33-xen)
> > >but grub gives me a unsupported executable format error 13?
> > >Cant i use the same image for a hvm guest ?
> >
> >
> >For HVM guests, you need an unmodified OS, so you can't use the same
> >kernel as with a PV guest. [Unless you load Xen in the guest that is
> >- but for most people that adds extra overhead for no extra gain, so
> >that's probably not such a good suggestion]
> >
> >---
> >Mats
> >
> >
> > >Thanks
> > >_______________________________________________
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> Xen-devel@xxxxxxxxxxxxxxxxxxx><mailto:Xen-devel@xxxxxxxxxxxxxxxxxxx>Xen-devel@xxxxxxxxxxxxxxxxxxx
> > > http://lists.xensource.com/xen-devel
> >
> >
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