Re: acpivga(4) v. MI display controls

[Jukka Ruohonen <jruohonen%iki.fi@localhost>]

On Fri, Oct 15, 2010 at 08:26:34AM +0300, Jukka Ruohonen wrote:
> The task is not trivial. On modern x86, practically *everything* that
> attachs has an ACPI counterpart. In a way we are thinking this backwards:
> the attachment should perhaps be done via ACPI that has information about
> the "natural" device tree (I recommend to boot with ACPIVERBOSE option and
> observe the output). This is how it is supposedly done in Windows. And
> consequently, *most* (MI) drivers that work on x86 need to eventually call
> (MD) ACPI callbacks, and vice versa. Bringing this all together in a clean
> (MI) implementation is hard and requires substantial changes, to say the
> least.

As an addition, due reasons stated above, I object anything that tries to
make a case for a single driver from acpi(4) -- be it acpivga(4), acpicpu(4),
or the ISA and PCI cases discussed previously. This should be solved once
and for all, for all acpi(4) and for all pci(4), isa(4), ... Otherwise we
end up with god-awful mess.

If such a solution comes to existence, we are happy to refactor acpi(4).
During the ten years that ACPI has been in NetBSD, several people have tried
a solution without much success. I have personally tried twice, and failed
already at the self-criticism stage.

- Jukka.