Re: [Xen-ia64-devel] [patch] calculate dom0 metaphysical load address correctly

[Jes Sorensen <jes@xxxxxxx>]

Isaku Yamahata wrote:
> On Thu, May 24, 2007 at 11:38:19AM +0200, Jes Sorensen wrote:
> P=M will break the current grant table api. It means all of virtual
> io device (balloon, vbd, vnif, ...) will be broken.
> What do you think about it?

Then we have to fix it - the Linux kernel requires this, it's not
optional. Sure it works for over simplified systems such as DIG, but
anything moderately advanced will break.

> In fact, Virtual Physical address model was introduced to
> resolve the grant table issue. And the ia64 default dma api and
> hp zx1 iommu are already paravirtulized.

There's much more to it than that. We need it for things like
alloc_pages_node() in the Linux kernel if we want any level of
performance.

>> In addition we want this
>> feature when we want to support multiple dom0's in the future.
> 
> Do you mean driver domain by "multiple dom0"?
> I.e. domain which can serves as backend.
> If so, it is already supported by pci backend/frontend driver.

I mean if we want to let individual dom's have direct access to a PCI
device. They will need to know where in the system it's physically
located.

Regards,
Jes



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