Hi,

this is how you can overclock a VIA C3 from 800MHz to 1000MHz in linux environnement.

The idea is to recompile the cpufreq associated to this type of processor. If you are lucky in the distribution you are using, it come as a module and you only have to compile the module. Otherwise you have no choice but to recompile the whole kernel.

Modification has to be done in :

arch/x86/kernel/cpu/cpufreq/longhaul.c

the driver is expecting the CPU to boot at mas FSB multiplier (

446: /* Get max multiplier - as we always did.
447: * Longhaul MSR is usefull only when voltage scaling is enabled.
448: * C3 is booting at max anyway. */

)

on my board ( VIA EPIA SP8000 ), FSB is 133MHz and startup multiplier is 6.
if I want to overclock to ~1GHz , I can set the max multiplier from 6 to 8 by doing :

449: maxmult = mult +20;

This file has not been modified in ages, so the line numbers should match for most of you.

OC’ing more than this lead to instability issues for me.