[OpenAFS-devel] i386_xenlinux26?

[Kyle Moffett]

On Jun 28, 2005, at 15:29:23, Troy Benjegerdes wrote:
> On Tue, Jun 28, 2005 at 01:50:37PM -0400, Jeffrey Hutzelman wrote:
>> Unfortunately, one of the properties of our current build system  
>> is that
>> for a different ${ARCH}, you have to have a different sysname.  So  
>> our
>> choices basically are to do a "port" with a sysname like  
>> i386_xenlinux26
>> (which would be consistent with how we handled UML), or wait for the
>> cleanups of which you speak, and hope the result will be the  
>> elimination of
>> arch/xen in favor of a config option.
>
> I think it would be less trouble for everyone in the long run to wait
> for the removal of arch/xen. If someone needs to hack up the openafs
> build system, maybe put a patch on the openafs web site, or someother
> place, but it probably shouldn't be put in the mainline cvs.

Agreed.

>> It's worth noting that the approach used by Xen requires an  
>> architecture
>> with more than two privilege levels, and while i386 and its  
>> relatives have
>> that feature, relatively few other architectures do.  So, it may  
>> be quite
>> some time before we see a xen for any other architecture.
>
> I'm not so sure.. Even if the Xen/x86 approach requires multiple
> priviledges, a virtualization system can work just fine using with the
> core virtual machine code running as priviledged, and everything else
> running upriviledged, and haveing the VM trap the 'illegal  
> instruction'
> handler to emulate priviledged operations. This is what Mac-on- 
> Linux does.
>
> http://www.maconlinux.org/

UML uses this trick as well

> There's even a note on the xen-users list about IBM working on a  
> Power5
> port.
>
> http://lists.xensource.com/archives/html/xen-users/2005-05/ 
> msg00433.html

The Power5 is a very different matter, because there, IIRC, Xen can use
the hypervisor to handle most of the work.  I think IBM even has Power5
systems that can run 2 or more copies of Linux independently, without
_any_ virtualization software (although I could be mistaken).

Cheers,
Kyle Moffett

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