@clvic
First: of course, I have tried on both
http://www.linux-laptop.net/ and
http://www.linlap.com/ but without success.
Second: if you could remember how to force insertion, that would be nice (even if i decide not to exploit it it is something one should be familiar with). As I remember there was some lilo option to instruct kernel to run certain options at boot. I should take a look at lilo's documentation.
Third: output from /proc/cpuinfo shows that my CPU has Enhanced SpeedStep capabilities (it is "est" flag in the flags list):
fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts pni monitor ds_cpl est tm2 ssse3 cx16 xtpr lahf_lm
@Ilgar
The idea has been to set up as much as possible without recompiling the kernel or compiling the new one. What you've suggested could solve the problem but I am trying to avoid that solution.
@keefay
Indeed it is, but if you modprobe acpi_cpufreq it calls the right module acpi-cpufreq.ko, so I don't think this causes problem. In fact I have tried to modprobe acpi-cpufreq and I have got the same problem. Nevertheless the correct syntax is as you noted and should be used.