Re: [XenARM] Initial porting on Xscale - George G. Davis - com.xensource.lists.xen-arm

3 messages in com.xensource.lists.xen-armRe: [XenARM] Initial porting on Xscale

From	Sent On	Attachments
ROSSIER Daniel	28 Sep 2007 11:55
George G. Davis	02 Oct 2007 08:05
ROSSIER Daniel	03 Oct 2007 10:03

Subject:	Re: [XenARM] Initial porting on Xscale
From:	George G. Davis (gda...@mvista.com)
Date:	10/02/2007 08:05:00 AM
List:	com.xensource.lists.xen-arm

On Fri, Sep 28, 2007 at 08:55:41PM +0200, ROSSIER Daniel wrote:

Hello,

We have now started the port of XEN on a Xscale/PXA270 processor (actually using
a Colibri board from Toradex).

For those w/o ARM target hardware and/or lacking hardware based debuggers, I'ld recommend using QEMU for bringup and debugging of Xen on ARM. In fact, I'ld recommend using QEMU even if you have the hardware and tools. Using QEMU for this task is quite convenient since gdbserver support is builtin so low-level target debugging can be performed on your development host with no ARM hardware and/or ARM debugging tools required. Alas QEMU may not include support for your specific target.

Ongoing work consists at porting the bootstrap code from XEN on the ARM without
enabling the virtualization mechanisms. The goal is to have a software infrastructure which is compliant
with the XEN tree organization and to have the right init code which works on the target machine.

In summary, what we are doing is to have the bootstrap code which gives the hand
to the XEN initialization code, which in turns starts the primary domain-0 Linux.

The init code will be strongly inspired from Daniel Ferstay's work as well as
the standard ARM arch-dependent code from the vanilla kernel (we're considering the 2.6.18 version).

Have you considered using linux-2.6.23-rc as a starting baseline? It already includes DomU paravirt support for x86. So perhaps this would be a good base line to start adding ARM paravirt support?

Then, we will gradually enable the virtualization part of the code (scheduler,
memory manager, etc.) in the hypervisor and adapt the bootstrap code accordingly. How will the XEN concepts be mapped on the ARM
remain an open issue, but for sure the work from Daniel Ferstay and your feedback and contribution will definitively help. I think we may also
consider the approaches presented by other ARM-target hypervisors such as
Iguana/L4, Jaluna, etc.

I hope to be able to post a first patch for the 2.6.18 kernel pretty soon.

I hope we're able to collaborate on this but I'm unable to make any commitments at this time. : (

Any hints, comments, suggestions, contributions are highly welcome and helpful.

Thanks a lot