Build procedure for cpufreq

1) download the advanced cpufreq patch from http://www.brodo.de/cpufreq/advanced.html
3) copy the 2.4.21-pre4 kernel tree to <dir1> and to <dir2>
4) apply patch-2.4.21-pre4-cpus_allowed to <dir1>
4) apply cpufreq-2.4.21-pre4-2_allowed to <dir2>
6) make distclean in each dir
7) diff between <dir1> and <dir2> to build the patch
8) rediff it against 2.4.21-pre5 (ignore the single rej)