Re: ACPI DSDT language

[Jan Slezak <jan.slezak-aRb0bU7PRFPrBKCeMvbIDA@public.gmane.org>]

Ducrot Bruno píše:
> 
> On Wed, Jan 29, 2003 at 10:33:52AM +0100, Ing. Jan Slezak wrote:
> > Ducrot Bruno pí?e:
> > >
> > > On Tue, Jan 28, 2003 at 11:47:03AM +0100, Jan Slezak wrote:
> > > > Hi,
> > > >
> > > > I would like to know what way should be buffers handled when are passed as arguments to
> > > > ACPI methods. I don't have a time to read the ACPI specs so I hope someone knows.
> > > >
> > > > I find out by tracing my /_TZ/TMP method that they are passed by value so following
> > > > construction (part of my original DSDT slightly modified) doesn't work (PNPG called)
> > > > because PGET is not modified:
> > > >
> > > >     Method (SX33, 2, NotSerialized)
> > > >     {
> > > >         If (LLess (Arg1, SizeOf (Arg0)))
> > > >         {
> > > >             CreateByteField (Arg0, Arg1, SX20)
> > > >             Store (Something, SX20)
> > > >         }
> > > >     }
> > > >
> > > >     Method (PNPG, 1, NotSerialized)
> > > >     {
> > > >       .
> > > >       .
> > > >         Name (PGET, Buffer (8) {})
> > > >         SX33 (PGET, 2)
> > > >         Return (PGET)
> > > >     }
> > > >
> > >
> > > Why don't make something like that instead:
> > >
> > >     Method (PNPG, 1, NotSerialized)
> > >     {
> > >       .
> > >       .
> > >         Name (PGET, Buffer (8) {})
> > >         Store (something, Index(PGET, 2))
> > >         Return (PGET)
> > >     }
> > >
> > > (unless 'something' is not 8-bits long, though)
> > >
> > > --
> > > Ducrot Bruno
> > >
> > > --  Which is worse:  ignorance or apathy?
> > > --  Don't know.  Don't care.
> >
> >
> > Sure, it is possible and I modified my DSDT in a similar way, but I want
> > to know if the original DSDT is correct (by specs, let's say
> > theoreticaly). I don't want to beat my notebok manufacturer and get the
> > answer "it is by spec" then.
> 
> Ah, yep, I have not read carrefully your first email.
> 
> By spec (2.0b, somewhere in 5.5.3 to 5.5.4):
> any namespace creation in a control method can only be acceded in the control method.
> 
> Here, the buffer PNPG will be created only for _internal_ use of PNPG.
> 
> When the SX33(PGET, 2) occur, the control method SX33 can not have direct
> access of PGET, but of a _local copy_ of the buffer (which is referenced by Arg0)
> but still only for _internal_ use of SX33.
> 
> Please note also that 'Return (PGET)' at end of PNPG control method will actually create
> a _copy_ for the caller of PNPG (the initial PGET will be destroyed at end of
> the method).
> 
> Cheers,
> 
> --
> Ducrot Bruno
> 
> --  Which is worse:  ignorance or apathy?
> --  Don't know.  Don't care.

Great! So I'm going to send my DSDT fix to Dell and ask them to apply it
to official BIOS.

Thanks,
Jan


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