CPU underclocking on Pentium M

[w_barnes]

Hello,

I'm using Knoppix on a Fujitsu laptop with a Pentium M processor and have noticed that Knoppix can underclock my cpu.
Specifically,

$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
1600000 1400000 1200000 1000000 800000 600000 400000 200000

I discovered the last two (400Mhz and 200Mhz) are below the nominal freq for the cpu after building Linux From Scratch on my laptop and checking the same file.

I did a little research and found there are several ways to underclock the cpu. How does Knoppix do it? I use the conservative freq governor for normal operation and powersave when on battery and would like to underclock when using LFS.

Thanks,
Walter