> > > Hey, > > > > > > you can set the maximum C-state to use using the > > > "processor.max_cstate=<value>" parameter. > No need to > > > recompile. > > > > Thanks for your kind reply. > > > > A stupid qustion: > > <value> is a numeric value as 1 , 2 , 3 > (i.e. processor.max_cstate=1 ) > > or is a string like C1 , C2 , C3 (i.e. > processor.max_cstate=C1 ) ? > > It's the former. I'd suggest you try max_cstate=2 first, as > that might save > power, reduce heat and still not interfere with the serial > device. MMhh , there is a problem in my kernel 2.6.24 (Ubuntu 8.04.3 original) [ 0.000000] Kernel command line: root=UUID=27d1e179-62d3-4996-878e-e4a456bd45f4 ro quiet splash acpi=force processor.max_cstate=2 [ 0.000000] Unknown boot option `processor.max_cstate=2': ignoring This is a known problem related to Ubuntu 8.04, solved here: http://www.inliniac.net/blog/2008/07/25/fixing-noise-on-ubuntu-hardy-804-aka-setting-max_cstate.html Really my idea is that my serial problems are involved with C3 state: 800 microsec. latency and cache loss. So I agree with your suggestion to use max_cstate=2. But it doesn't work: serial overrun still there. max_cstate=1 works fine : no overrun at all. C2 state is buggy too. I don't know if it's a hardware problem or acpi code problem, but with C1 it works fine and I'm happy :-) -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
