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

[Paolo Bonzini]

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.

While these registers can be separated from the ACPI code in QEMU...

> and I speculate that there is some IRQ
> assigned to an ACPI event that causes some AML code to be interpreted by
> your OS.

... QEMU does exactly this, it uses the "general purpose event" (GPE)
mechanism to trigger the parsing of the AML.  When you hot-plug/unplug a
CPU or memory, an SCI (system control interrupt - the ACPI IRQ) is
triggered in the guest and that's not entirely disconnected from ACPI.

Perhaps you could treat it as a shared level-triggered interrupt in DT?
 I don't know.

> Wouldn't it be a matter of QEMU putting the right AML table
> fragments in place to wire this up then?

Yes.

Paolo