Re: [Qemu-devel] [RFC v1 1/2] arm: Add the cortex-a9 CPU to the a9mpcore device

[Peter Crosthwaite]

On Tue, Jun 17, 2014 at 6:05 PM, Paolo Bonzini <address@hidden> wrote:
> Il 17/06/2014 09:16, Stefan Hajnoczi ha scritto:
>
>> > The bigger issue though is how do you do an N:1 mapping. The container
>> > should only have 1 "midr" prop, but it should mirror to all contained
>> > CPUs. Should we add multiplicity to the aliasing feature?
>>
>> If we'll need 1:N alias properties in other places too.

Well A15 MPCore is the obvious one. Any homogeneous n-way container
that wants to forward props could make use of this.

>
>
> I think in the case it's the contained object that should look for a midr
> property in the parent, and possibly create an alias to the parent's midr
> property.
>

This sounds too difficult to me. How do you define whether a contained
object is allowed to go looking into a parent for suitable aliasing
oppurtunities without container level knowledge?

The contained object should also be able to create it's property
regularly in cases where the parent does not provide an aliasable
which adds some ugly iffery to the contained's init fn.

Ultimately I think the container should remain in full control and do
the 1:N aliasing in a loop when appropriate.

And some further food for thought, if we throw Andreas' heterogenous
MPCore idea (one of the tangent topics on this thread) in the mix, a
container will want to potentially alias the same property on two
different children to two different props on the child. The child
simply cannot handle this without knowing too much about it's
container.

Regards,
Peter

> Paolo
>