Re: [Xen-devel] [help]: handling IO instructions for hybrid

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 08/02/2012 18:17, "Mukesh Rathor" <mukesh.rathor@xxxxxxxxxx> wrote:

> On Mon, 06 Feb 2012 19:41:23 +0000
> Keir Fraser <keir.xen@xxxxxxxxx> wrote:
> 
>> On 07/02/2012 02:26, "Mukesh Rathor" <mukesh.rathor@xxxxxxxxxx> wrote:
>>> 
>>> I am figuring io access for hybrid guests, dom0 and domU. I see
>>> that there are two ways: PV -> emulate_privileged_op(), or hvm
>>> handles via handle_mmio()/handle_pio(). I am not familiar with
>>> either one, and would help me lot if anybody expert in that can
>>> suggest which way hybrid should go, both dom0 and domU. Any
>>> suggestions would help. If there are any docs on this, that would
>>> be great too.
>> 
>> Probably the PV route, for dom0 and domU. Really most things you want
>> to do, the PV route is going to be the right way (unless you are
>> PVHVM'ing certain things, e.g., like using EPT assistance for
>> pagetable handling).
>> 
>>  -- Keir
> 
> Thanks Keir. Just to confirm, the hybrid should continue to request
> iopl of 1, right?

I'm not sure it matters since the hybrid guest runs in ring 0 of non-root
context I believe? Since ring 1 is in that case unused, it doesn't matter
whether iopl is 0 or 1.

 -- Keir



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