Hi, all! I just both a new laptop and of course installed Linux on it. It has a Intel Celeron M processor, and I can't quite figure out what it is capable of. I'm running kernel 2.6.11. The only power saving feature I have managed to get working is frequency scaling using the p4-clockmod module. When I install it I get the warning:
p4-clockmod: Warning: Pentium M detected. The speedstep_centrino module offers voltage scaling in addition of frequency scaling. You should use that instead of p4-clockmod, if possible. p4-clockmod: P4/Xeon(TM) CPU On-Demand Clock Modulation available If I try to load the speedstep_centrino module, I get the error: FATAL: Error inserting speedstep_centrino: No such device What I've managed to find out, is that the Celeron M processors don't have the 'SpeedStep' technology, it's only included in the Pentium Ms. But excluding some marketing talk, I couldn't figure out what EXACTLY 'Speedstep' ot 'Enchanced Speedstep' is. The most useful doc I got my hands on is a feature comparision table of the Celeron M and Pentium M processors at http://support.intel.com/support/processors/mobile/pm/sb/CS-007967.htm According to this my CPU does not have 'SpeedStep' but has Mobile Voltage Positioning - MVP IV. It has family/model/stepping of 6/13/16 and is identified (incorrectly, I think) as a DOTHAN_B0 by speedstep_centrino.c. Here's the output of 'cat /proc/cpuinfo': processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 13 model name : Intel(R) Celeron(R) M processor 1.30GHz stepping : 6 cpu MHz : 162.168 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr mce cx8 apic mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss tm pbe bogomips : 2555.90 Is MVP the official name for what in the linux kernel is refered to as voltage scaling? Does this CPU have 'voltage scaling' and if yes, how can I get it to work under Linux. If the Celeron Ms have frequency scaling (which they obviously do) and MVP (supposedly voltage scaling), then what is this '(Enchanced) SpeedStep' thing which they don't have? Any ideas/solutions are welcome! Best regards, Rado
