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

[Peter Maydell]

On 5 November 2014 09:58, Claudio Fontana <address@hidden> wrote:
> Please correct me if I am wrong, my understanding at the moment is that
> for X86 there is an ACPI implementation in hw/acpi, with the table generation
> happening in hw/i386/acpi-build.c .
> Couldn't there be some unification where part of the infrastructure for
> ACPI is reused, with arch-specific code specializing for X86 and ARM?
> Why are ACPI tables created for X86, but cannot be created likewise for ARM?

Because then for ARM boards we'd be creating a description of the
hardware twice, once in device tree and once in ACPI, which seems
like unnecessary duplication.

> We need ACPI guest support in QEMU for AArch64 over here, with all features
> (including the ability to run ACPI code and add specific tables), for
> ACPI-based guests.

The plan for providing ACPI to guests is that we run a UEFI BIOS
blob which is what is responsible for providing ACPI and UEFI
runtime services to guests which need them. (The UEFI blob finds
out about its hardware by looking at a device tree that QEMU
passes it, but that's a detail between QEMU and its bios blob).
This pretty much looks like what x86 QEMU used to do with ACPI
for a very long time, so we know it's a feasible approach.

thanks
-- PMM