Re: [Xen-devel] Inter-domain shared memory facility in Xen? - Haifeng He - com.xensource.lists.xen-devel

9 messages in com.xensource.lists.xen-develRe: [Xen-devel] Inter-domain shared m...

From	Sent On	Attachments
David Stone	30 Oct 2007 12:50
Akio Takebe	30 Oct 2007 21:00
Haifeng He	30 Oct 2007 23:24
Akio Takebe	31 Oct 2007 00:27
David Stone	01 Nov 2007 06:40
Daniel Stodden	01 Nov 2007 07:13
Derek Murray	01 Nov 2007 07:16
David Stone	01 Nov 2007 08:30
Mark Williamson	02 Dec 2007 20:21

Subject:	Re: [Xen-devel] Inter-domain shared memory facility in Xen?
From:	Haifeng He (heha...@gmail.com)
Date:	10/30/2007 11:24:35 PM
List:	com.xensource.lists.xen-devel

Hi,

I had a similar question on another email thread and I have a following question. If I understand correctly, I need to change the kernels of domUs to make the sharing happen (explicitly call those APIs). Is it possible to do the sharing without changing domUs? In another word, is it possible to let Xen, the hypervisor, to perform the sharing transparently without modifying domUs. For example, Xen can share all the identical pages among domUs and apply Copy-On-Write on them. I guess, it requires changes inside the Xen's memory management. Any suggestion on how it may be possible?

Thanks

Haifeng

On 10/30/07, Akio Takebe <take...@jp.fujitsu.com> wrote:

Hi,

Hopefully this question belongs in xen-devel and not xen-users:

Is there any kind of inter-domain shared memory facility in Xen? E.g. an API callable from DomU user-mode that would cause the system sets up two DomU's page tables so they a range of virtual addresses in both resolve to the same set of machine pages?

You may be able to use grant table. Grant table can make shared memroy.

If you want to share memory between dom0 and domU, you can use the following fanction.

1. HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref) and gnttab_grant_foreign_access() It is kernel API used in blk split driver.

2. xc_map_foreign_range() It is dom0 user API used in xc_core.c. It can share memory between dom0 user vaddr and domU guest maddr.

If you want to share memory between domU user vaddr and the other domU's, you need to make the API.

Best Regards,