Re: [Qemu-devel] [Linaro-acpi] [RFC PATCH 0/7] hw/arm/virt: Dynamic ACPI v5.1 table generation

[Paolo Bonzini]

On 12/11/2014 13:18, Mark Rutland wrote:
> On Wed, Nov 12, 2014 at 11:48:27AM +0000, Paolo Bonzini wrote:
>>
>> On 12/11/2014 12:34, Christoffer Dall wrote:
>>> AFAIU ACPI already has a method for doing this
>>
>> It's not defined in the spec.  QEMU defines a bunch of registers to do
>> that, and provides AML that works with those registers.
> 
> Huh? SCI + AML is the method, and that's defined by the spec.

I thought Christoffer meant a method to do the actual hotplug, not just
to signal events.  If you want to "support the low-level interfaces in
the kernel for this anyway", you certainly need to know the details
underneath the AML.

>> Perhaps you could treat it as a shared level-triggered interrupt in DT?
>>  I don't know.
> 
> Putting an interrupt in DT is trivial. The hard part is the rest of the
> interface, which so far there is no specification for.

Have you looked at docs/specs/acpi_{cpu,mem}_hotplug.txt?  Writing a DT
binding for it is trivial too.  Or are we talking about two different
things?

Paolo