Re: ACPI C4 support

[Pavel Machek <pavel-AlSwsSmVLrQ@public.gmane.org>]

Hi!

> > [mailto:acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org] On Behalf Of 
> > Stefan Behlert
> > > No.  pblk_length is 0 or 6.  Not 5 nor 7 ;)
> > 
> > Sorry, I don't understand: We've a Laptop with a DSDT with
> >   Processor (\_PR.CPU0, 0x01, 0x00001010, 0x07)
> > in it.
> > Comment from the responsible BIOS-team:
> > "Our processor block object is 7 bytes in length because we 
> > also support
> >  C4 (P_LVL4) which is at <P_BLK>+6.  Therefore, the 
> > size/length must be
> >  reported as 7 and not 6."
> > 
> > Is the '7' the BIOS-developer mentioned the same '7' as 
> > mentioned by you?
> 
> This is wrong.
> 
> There is confusion here because what older systems do on C3 is different
> from what more recent systems do on C3, at the electrical level. I know
> at least internally the improved C3-like state was called "C4" but to
> the OS it just looks just like C3, and the value for C4 should go in
> P_LVL3. P_BLK length should remain 6.
> 
> The only way to get more than C1, C2, and C3 is via the _CST object.
> 
> Please tell the BIOS developer this. I have an old BIOS developers guide
> version that agrees with them but I just asked the experts internally
> and they said no.

If there is old BIOS guide telling them to use length of 7, could we
make Linux accept that? Its likely a lot of developers have read
that...

Allowing length of 7 is one line change; if we do it, such notebooks
will be able to use C1..C3, but not C4. That does not seem too bad...

								Pavel
-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]


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