/proc/sys/cpu interface and elanfreq on linux 2.4.20

Hello,

I applied a cpufreq patch (http://www.codemonkey.org.uk/projects\
/cpufreq/cpufreq-2.4.21-2.gz) to a linux 2.4.20 tree without any problems, and compiled with the following (default) settings for an AMD Elan cpu:

    CONFIG_CPU_FREQ=y
    CONFIG_CPU_FREQ_TABLE=y
    CONFIG_CPU_FREQ_PROC_INTF=y
    CONFIG_CPU_FREQ_GOV_USERSPACE=y
    CONFIG_CPU_FREQ_24_API=y
    CONFIG_ELAN_CPUFREQ=m

The just created module `elanfreq.o' has been loaded smoothly into the kernel, and in /proc/cpufreq I can see

          minimum CPU frequency  -  maximum CPU frequency  -  policy
CPU  0         1000 kHz (  1 %)  -      66000 kHz (100 %)  - performance

But I wonder about why both /proc/sys/cpu/0/speed-min and -max contain zero, and speed' always shows the maximum frequency. If I echo a value out of the list in elanfreq.c into speed', there is no reaction, elanfreq_target() will not be called (with one exception:
When initializing, the value specified by `max_freq' will be set twice via elanfreq_target).

Am I missing something, does perhaps "deprecated interfaces" mean, the userspace access via /proc/sys/cpu might not work?

Michael Teichgräber

According to /usr/src/linux/Documentation/cpufreq/user-guide.txt :

"These are files (/proc/sys/cpu/0/* ) for deprecated interfaces to cpufreq, which offer far less functionality."

Many functionality are missing (have a look on user-guide for more details) but the userspace stuff works. In fact you just forgot to activate it. To do so (you must be root):

$ echo -n "0%0%100%userspace" > /proc/cpufreq

and then you should have

$ cat /proc/sys/cpu/0/*
66000
66000
1000

Now you can echo the frequency you want in /proc/sys/cpu/0/speed ! Enjoy !!!

Mike

Thanks, this made it work.

Michael