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

[Paolo Bonzini]

Il 21/01/2014 12:02, Michael S. Tsirkin ha scritto:
> > 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.
> 
> Insane, yes.
> This is however what windows does and this is what microsoft document
> explicitly says.

Yeah, that's what I would like a source for.  _How_ does Microsoft tweak
its ACPI implementation based on the set of feature bits that are
_OSI-probed?

But even that is not very important because...

> We restrict ourselves to a very small subset of the spec
> that seems to work well everywhere, and
> so far OSPMs seem to assume that's what no _OSI means.

... do we have reason to believe that adding _OSI("Darwin") will make
some OSPM *restrict* their features further?  I don't think so.

Besides being doubly insane to me, it contradicts the spec.  The spec
says that _OSI probes can be used by the OSPM to provide *more*
features, not less.  It says "OSPM can choose to expose new
functionality" based on the _OSI argument string.

So only Mac OS X has to be tested if we probe _OSI("Darwin").

Paolo