On Tue, 16 Dec 2003 08:43:48 -0500 "andy@epox.org" andy@epox.org wrote:

This is strictly a bios only feature supported by all retail Clawhammer and Newcastle cores.

The BIOS needs to supply an usable PST table (many don't unfortunately), but it is actually handled on linux by a kernel driver (powernow-k8) and cpufreqd. When you have a working PST table it should just work out of the box on 9.0/AMD64. It will only work on Athlon64 boxes, no Opteron or FX.

The BIOS also does some power management using C* states and SMM code and ACPI, but these are not what Cool'n'Quiet refers to.

When the PST table is ok and you have the right CPU you should see a message like:

powernow-k8: version 1.00.08 - September 26, 2003 powernow-k8: Found AMD Athlon 64 / Opteron processor supporting p-state transitions powernow-k8: voltage stable time: 5 (units 20us) powernow-k8: p states on battery: 0 - all available powernow-k8: ramp voltage offset: 2 powernow-k8: isochronous relief time: 3 powernow-k8: maximum voltage step: 0 powernow-k8: pll lock time: 0x2 powernow-k8: maxfid: 0xa powernow-k8: maxvid: 0x0 powernow-k8: numpstates: 0x3 powernow-k8: 0 : fid 0x0, vid 0xa powernow-k8: 1 : fid 0x8, vid 0x6 powernow-k8: 2 : fid 0xa, vid 0x2 powernow-k8: currfid 0xa, currvid 0x2 powernow-k8: cpu_init done, current fid 0xa, vid 0x2

in /var/log/boot.msg. You can then either let cpufreqd do the work based on the load average or change the frequency manually using rccpufreqd low/high

-Andi