RE: [Xen-devel] [BUNDLE] Testing a simpler inter-domain transport

["Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>]

Hi Fred --

My recollection is that we agreed (with the IBM PPC guys also)
that dom0 should use virtual-physical (VP), except for DMA
which would be forced to use a software IOMMU.

Note that Rusty's idt code replaces the existing VBD/VNIF
and grant table mechanism, so it would be nice to ensure
it is more portable before it becomes part of the Xen core.

Dan

> -----Original Message-----
> From: Yang, Fred [mailto:fred.yang@xxxxxxxxx] 
> Sent: Monday, February 06, 2006 1:48 PM
> To: Magenheimer, Dan (HP Labs Fort Collins); 
> xen-devel@xxxxxxxxxxxxxxxxxxx
> Cc: Rusty Russell; xen-ia64-devel
> Subject: RE: [Xen-devel] [BUNDLE] Testing a simpler 
> inter-domain transport
> 
> Dan,
> 
> From Xen summit, isn't it to be more P2M liked approach due to
> consideration on driver domain and domain0 needs to get P2M for
> VBD/VNIF?   
> 
> Don't remember there is decision on taking Hypercall only approach and
> dropped P2M table lookup.  Any justification here?
> 
> -Fred
> 
> Magenheimer, Dan (HP Labs Fort Collins) wrote:
> > (I'm sure you meant PPC *and* ia64 ;*)
> > 
> > On just a quick skim, one thing to note:
> > 
> > IIRC from the summit, domain0 and driver domains for
> > neither PPC nor ia64 will have a p2m lookup table so
> > a p2m translation will require a hypercall. So
> > while virt_to_machine is cheap for domains on x86,
> > it is not on PPC and ia64.  If HYPERVISOR_share can
> > take physical addresses instead of machine addresses
> > (with Xen doing the phys_to_machine part of the
> > translation), I think the code would work better
> > for PPC and ia64, as well as better hide the
> > virtual->physical->machine memory abstraction.
> > 
> > Dan
> > 
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> 
> 

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