Re: [Xen-devel] Inter-domain shared memory facility in Xen?

["Haifeng He" <hehaifeng2nd@xxxxxxxxx>]

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 <takebe_akio@xxxxxxxxxxxxxx> 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,
>
> Akio Takebe
>
>
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>

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