Re: [Qemu-devel] RFC: ACPI, HPET._CRS, MacOSX vs. WinXP

[Paolo Bonzini]

Il 20/01/2014 22:25, Gabriel L. Somlo ha scritto:
> 
>  "Implementation Note
>   Place the routine that identifies the operating system in an _INI method
>   under the \_SB scope so that _OSI can run as early as possible. This
>   placement is important because the operating system makes features
>   available based on the string argument to the _OSI method."
> 
> It all depends on what the document's author meant by "the operating
> system" which "makes features available". Because somewhere earlier in
> the document they say:
> 
>  "Recent versions of the ACPI spec have extended the use cases of
>   the _OSI method beyond host operating system version identification.
>   However, Windows supports _OSI only for the use of identifying the host
>   version of Windows that is running on the system."

I read that as referring to things like _OSI("3.0 Thermal Model").  It
means (the way I read it) that Windows will not publish that kind of
_OSI string.

I think it is safe to assume that no OSPM will do those crazy things
with OS-defined _OSI strings (it's quite plausible that they do it with
feature _OSI strings).

First, because IMHO it is completely insane.

Second, because the current DSDT would also be theoretically broken with
an OSPM that does strange things with _OSI.  We never call _OSI, so the
OSPM could presume that it should "disable all features".

Paolo