Subject: Keyboard and mouse problems in Xen after enabling est driver.
To: None <>
From: Juraj Hercek <>
List: port-xen
Date: 08/21/2006 19:22:59
Hello people,

I've been experimenting with xen3 dom0 a bit in a way that I can run est 
(enhanced speedstep) driver in dom0 on my PentiumM notebook. I did it 
because I hate the fan noise poisoning my life when cpu gets hot during 
my plays with xen. The best way to limit cpu heat is to set frequency to 
600MHz which is possible with having est driver working in dom0.

The main task was to enable reading/writing msr registers from dom0 
using dom0_op(dom0_op_t *op) administrative function (changed rdmsr() 
and wrmsr() in cpufunc.h file) and then incorporating est into code. 
After I have done all the stuff mentioned above, I found out that i) I 
can set frequency and voltage on cpu in dom0, but ii) keyboard and mouse 
got crazy... :(

The keyboard have some strange problem with repeat rate, when lowering 
frequency from 2000 -> 600 I experienced double (sometimes also tripple) 
keystrokes on console. When I returned frequency back to 2000 everything 
is fine (similary with other frequencies from range 600-1800). Also, 
mouse has some problems because I get 'pms0: resetting mouse interface' 
or something like that on console effectively preventing me from having 
comfortable X session.

I poke a bit into wscons driver since it seems to be related to the 
problem. There are couple of lines that use "hz" parameter which could 
potentially cause my headaches but I didn't get farther...

Anyways I would like to know your opinion(s) regarding following questions:
1) Why the est driver doesn't cause problems in standard kernel?
2) Is there a way to avoid problems with mouse/keyboard (without 
disabling frequency scaling)?