[coreboot] coreboot specific ACPI table

[Aaron Durbin]

On Mon, Apr 18, 2016 at 10:17 PM, Julius Werner <jwerner at chromium.org> wrote:
> I think we should only export the coreboot table location and size
> through ACPI and then read everything else from there. That way we can
> share almost all of the kernel driver code with ARM and just need a
> tiny platform-specific stub to look up the table location first. If we
> add all the information into an actual ACPI table, we're building an
> x86-only solution again. (A generic, platform-independent coreboot
> driver could just as easily export the stuff we want into sysfs.)
>

That's fine. The only thing I was concerned about was implementing an
ACPI table proper or try to do some ACPI device shenanigans like the
ramoops device. coreboot doesn't currently have a ACPI ID assigned to
it. If we go with a ACPI device coreboot should apply for an ACPI ID.
I personally think the coreboot ACPI table seems more straight
forward, but I was wondering if people knew of any downsides to going
that route.

> For comparison, the coreboot device tree interface on ARM
> (https://lkml.org/lkml/2014/6/16/622, unfortunately never picked up by
> the maintainers but still used on Chromebooks today) only exports
> start address and size of the coreboot table and the whole CBMEM area,
> so maybe ACPI should just match that. (I guess if CBMEM is referenced
> by the coreboot table like Aaron said, we could also drop that part.)