Re: Booting a NetBSD 4 domU on a Linux dom0?

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Wed, Mar 28, 2007 at 05:35:36PM -0400, Chris Ross wrote:
> 
>   I did some googling around, and found mostly information in the  
> archives of this mailing list.  I hope this isn't a question that's  
> been answered "too many times".
> 
>   The information I found seemed to mostly deal with running a  
> NetBSD dom0, of course, and with older versions of NetBSD.

The changes to use a linux dom0 should only be marginal, and you'll spot
them easily (device names in the config file, mostly) if you already have
a linux domU running.

> I have  
> NetBSD 4ish (the current top of the netbsd-4 branch) built, and want  
> to run it on a big machine I have at work running Xen 3.0.3 with an  
> Ubuntu 6.06 userland.  This is an amd64 machine, running on a machine  
> with HVM support, so it can do full virtualization, but I don't want  
> it to.

Running 32 or 64bit linux ? NetBSD/Xen only runs on 32bit hosts for now.

> 
>   What would I have to do to create a domU that I could install  
> NetBSD onto?  Does the ISO generated with the new 'iso-image'  
> build.sh target know how to boot a para-virtualization aware kernel  
> on a machine?

For Xen native domU, the kernel is loaded from dom0's filesystem.
the disk/cdrom/whatever images used for virtual disks are only used once
the kernel is running.
What you need to do the install is the netbsd-INSTALL_XEN3_DOMU.gz kernel.
Once the install is complete, halt the domU and boot it with
netbsd-XEN3_DOMU.gz

> I don't want to end up running fully virtualized,  
> which I suspect is what would happen with a GENERIC kernel.  Is it  
> even possible/practical to run para-virtualized with i386 on an amd64  
> machine?

This I don't know, I've never tried it on a 64bit OS. I ran NetBSD/i386
on a para-virtualized guest on a i386 dom0, and it's as fast as a native Xen
guest for CPU-bound tasks. I/O are slow.

> If I build amd64 netbsd-4 code, can that run under a linux  
> dom0 (2.6.16.29-xen) ?

No, we don't have 64bit support in Xen yet.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--