cvs commit: src/sys/dev/acpica acpi_cpu.c

[John Baldwin]

On Wednesday 17 March 2004 09:50 pm, Nate Lawson wrote:
> On Wed, 17 Mar 2004, John Baldwin wrote:
> > On Wednesday 17 March 2004 04:49 pm, Nate Lawson wrote:
> > > njl         2004/03/17 13:49:47 PST
> > >
> > >   FreeBSD src repository
> > >
> > >   Modified files:
> > >     sys/dev/acpica       acpi_cpu.c
> > >   Log:
> > >   Fix border error to allow systems that specify 100 for latency also
> > > use C2 and 1000 to use C3.
> > >
> > >   Submitted by:   Bruno Ducrot <ducrot at poupinou.org>
> > >   Tested by:      Scott Lambert <lambert at lambertfam.org>
> >
> > Hmm, the BIOS on my laptop uses those values when the C states are
> > disabled (according to the BIOS text).  That is, my BIOS lets me turn C2
> > and C3 on and off.  When turned on, it uses the values 1 and 85 for the
> > latency, and when off it uses 100 and 1000.  Note that the kernel never
> > uses C3 on this machine by the way with these latencies:
> >
> > hw.acpi.cpu.cx_supported: C1/1 C2/1 C3/85
>
> That's incorrect behavior.  See Table 5-8 of the ACPI 2.0 spec (at or near
> page 102).  Have you actually done an acpidump -t both with and without C2
> disabled in your BIOS to see what it does?  Perhaps the manual is wrong
> and it does the right thing.  In any case, your failure mode (not being
> able to disable Cx states in BIOS) is not as bad as others (not being able
> to use C2 when it's supported.)  You can always keep using the sysctl to
> disable C2 and/or C3.

What about the second problem I reported that the kernel doesn't ever use C3 
on this machine?

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org