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

[Peter Maydell]

On 30 October 2014 17:43, Alexander Spyridakis
<address@hidden> wrote:
> Currently, the virt machine model generates Device Tree information 
> dynamically based on the existing devices in the system. This patch series 
> extends the same concept but for ACPI information instead. A total of seven 
> tables have been
> implemented in this patch series, which is the minimum for a basic ARM 
> support.
>
> The set of generated tables are:
> - RSDP
> - XSDT
> - MADT
> - GTDT
> - FADT
> - FACS
> - DSDT
>
> The tables are created in standalone buffers, taking into account the
> needed information passed from the virt machine model. When the generation
> is finalized, the individual buffers are compacted to a single ACPI binary
> blob, where it is injected on the guest memory space in a fixed location.
> The guest kernel can find the ACPI tables by providing to it the physical
> address of the ACPI blob (e.g. acpi_rsdp=0x47000000 boot argument).

(Sorry, I should have waited for the cover letter to arrive before replying.)

I think this is definitely the wrong approach. We already have to
generate device tree information for the hardware we have, and having
an equivalent parallel infrastructure for generating ACPI as well
seems like it would be a tremendous mess. We should support guests
that require ACPI by having QEMU boot a UEFI bios blob and have that
UEFI code generate ACPI tables based on the DTB we hand it.
(Chances seem good that any guest that wants ACPI is going to want
UEFI runtime services anyway.)

thanks
-- PMM