Re: [Xen-devel] [virtio-dev] Re: VIRTIO - compatibility with different virtualization solutions

[Rusty Russell <rusty@xxxxxxxxxxx>]

Anthony Liguori <anthony@xxxxxxxxxxxxx> writes:
> On Thu, Feb 20, 2014 at 4:54 PM, Rusty Russell <rusty@xxxxxxxxxxx> wrote:
>> On the other hand, if we wanted a more Xen-like setup, it would looke
>> like this:
>>
>> 1) Abstract away the "physical addresses" to "handles" in the standard,
>>    and allow some platform-specific mapping setup and teardown.
>
> At the risk of beating a dead horse, passing handles (grant
> references) is going to be slow.
...
> I really think the best paths forward for virtio on Xen are either (1)
> reject the memory isolation thing and leave things as is or (2) assume
> bounce buffering at the transport layer (by using the PCI DMA API).

Xen can get memory isolation back by doing the copy in the hypervisor.
I've always liked that approach because it doesn't alter the guest
semantics, but it's very different from what Xen does now.

Cheers,
Rusty.


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