Date: Thu, 4 Feb 2010 17:29:18 -0500 From: John Baldwin <jhb@freebsd.org> To: Andriy Gapon <avg@icyb.net.ua> Cc: freebsd-acpi@freebsd.org Subject: Re: acpi_cpu: _PDC vs _OSC Message-ID: <201002041729.18714.jhb@freebsd.org> In-Reply-To: <4B6B4689.4020708@icyb.net.ua> References: <4B698DD8.4010404@icyb.net.ua> <201002041657.52232.jhb@freebsd.org> <4B6B4689.4020708@icyb.net.ua>
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On Thursday 04 February 2010 5:13:29 pm Andriy Gapon wrote:
> on 04/02/2010 23:57 John Baldwin said the following:
> > On Thursday 04 February 2010 2:42:47 pm Andriy Gapon wrote:
> >> - * TODO: evaluate failure of _OSC.
> >> + * On some systems evaluation of _OSC/_PDC dynamically
> >> + * loads the _PSS and other methods.
> >> */
> >
> > I would only say _OSC here. I don't think we've seen any systems that
load
> > something when _PDC is invoked, only when _OSC is invoked.
>
> Actually, I think that the way it's written should be OK.
> I've seen a few DSDTs where both are present and both do the same thing.
> E.g.:
>
> Scope (\_PR.CPU0)
> {
> Name (HI0, Zero)
> Name (HC0, Zero)
> Method (_PDC, 1, NotSerialized)
> {
> Store (CPDC (Arg0), Local0)
> GCAP (Local0)
> Return (Local0)
> }
>
> Method (_OSC, 4, NotSerialized)
> {
> Store (COSC (Arg0, Arg1, Arg2, Arg3), Local0)
> GCAP (Local0)
> Return (Local0)
> }
> ...
>
> Looks like CPDC is "Convert _PDC" and COSC is "Convert _OSC" and GCAP is
"G...
> capabilities", whatever "G..." could mean.
But is GCAP loading an additional SSDT? That is what the "loading something"
refers to and I think we've only observed that occurring with _OSC. I'd
rather we only document unexpected quirks that someone has actually reported
and not assume that just because an _OSC method on some box did it, there's
bound to be a _PDC method on some other box that does it. In truth, the
comment is probably not needed now anyway since this will always do _OSC
first.
--
John Baldwin
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