4 messages in com.xensource.lists.xen-develRE: Guest-visible phys2mach part of X...| From | Sent On | Attachments |
|---|---|---|
| Tian, Kevin | 29 Dec 2005 18:20 | |
| Magenheimer, Dan (HP Labs Fort Collins) | 30 Dec 2005 11:13 | |
| Kevin Fox | 30 Dec 2005 13:00 | |
| Ewan Mellor | 30 Dec 2005 14:38 |
| Subject: | RE: Guest-visible phys2mach part of Xen arch-neutral API? was:[Xen-devel] Uses of &frame_table[xfn] |
|---|---|
| From: | Magenheimer, Dan (HP Labs Fort Collins) (dan....@hp.com) |
| Date: | 12/30/2005 11:13:48 AM |
| List: | com.xensource.lists.xen-devel |
Yes, that's the current status: No way to see underlying machine address in other domains and thus no way for driver domains.
Itanium cluster (~1000 nodes). I'm not sure if it would be possible to use Xen on the cluster without driver domains though. Just food for
Just to clarify: This doesn't say that there can't be driver domains. Driver domains would need to be implemented p==m, same as domain0, except they would need to be given a different EFI memory map. They have not been implemented on Xen/ia64 because they have not yet re-appeared in Xen/x86.
But I am intrigued by your statement... are you assuming that Xen and domain0 are both single-system-image across the 1000+ nodes? I think one of the difficulties with implementing driver domains is that Xen (in the hypervisor) needs to discover and somehow partition all the devices. This could be a real challenge for huge clusters.
Thanks, Dan
-----Original Message----- From: Kevin Fox [mailto:Kevi...@pnl.gov] Sent: Friday, December 30, 2005 9:35 AM To: Tian, Kevin Cc: Keir Fraser; Magenheimer, Dan (HP Labs Fort Collins); Xen Mailing List Subject: RE: Guest-visible phys2mach part of Xen arch-neutral API? was:[Xen-devel] Uses of &frame_table[xfn]
There has been some discussion about some day using Xen on our large Itanium cluster (~1000 nodes). I'm not sure if it would be possible to use Xen on the cluster without driver domains though. Just food for thought.
Kevin
PS. I'm fairly disappointed in the lack of focus that driver domains are receiving in Xen. I use them on several machines (one in production) and I think it counts among Xen's greatest features.
On Fri, 2005-12-30 at 10:16 +0800, Tian, Kevin wrote:
From: Keir Fraser [mailto:Keir...@cl.cam.ac.uk]
Sent: 2005年12月29日 21:48
On 29 Dec 2005, at 01:59, Tian, Kevin wrote:
IMO, I see the phys2mach mapping as a basic virtualization policy, instead of an architecture specific requirement. After adding phys2mach concept to XEN/IA64, we can reuse more common code without ifdef. Then correspondingly also need to add several necessary changes like x86: DMA, SWIOTLB, AGP, etc, to ensure legal machine address written into physical devices.
This seems to make sense to me. How does ia64/xen work right now? Machine addresses visible to domain0 and full virtualisation of addresses exposed to other domains (with no way of seeing underlying machine addresses)?
-- Keir
Yes, that's the current status: No way to see underlying machine address in other domains and thus no way for driver domains.
Thanks, Kevin
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