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

[Paolo Bonzini <pbonzini@redhat.com>]

On 12/11/2014 15:10, Mark Rutland wrote:
>>> We can't just pick-and-mix
>>> portions of ACPI and state that it's specified and standard.
>>
>> But that's what you already do if you want to build ACPI tables from DT.
>>  You are already picking-and-mixing the variable portions of the ACPI
>> tables and make a DT bindings for them.
> 
> I don't follow. I argued _against_ trying to build ACPI tables from DT
> because the two don't quite match up anyway. I argued _against_ trying
> to convert ACPI tables to DT in prior discussions for similar reasons.

Sorry, that was not you-Mark, but more you-ARM.

And in fact I'd tend to agree with you, but if there are people that
want not to use ACPI or UEFI or both, I think it's better if the UEFI
firmware swallows the same pill and builds ACPI from DT.

> In addition to fixing up the other specs which are affected by this
> (e.g. how we describe those additional CPUs). There's also some
> de-ACPIing to be done in addition to de-x86ification, and we need to be
> careful to ensure we have access to all the information we require in
> the absence of ACPI, and that we have a well defined behaviour on both
> sides of the interface for what would previously have been implicit in
> ACPI.

Yes, I agree.  On the QEMU side the de-ACPIfication would have to be
done anyway (no GPE because of the reduced hardware), but you need extra
de-ACPIfication for stuff like the SRAT.

> I'm not saying that this is impossible. It's just a greater body of work
> than modifying one spec.

No doubt about that.

Paolo