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ilbh
23rd November 2006, 07:32 AM
what is that xen kernel stuff ?

galatei
23rd November 2006, 10:13 AM
Bryan Clark (bclark@redhat.com), Interaction Designer, Red Hat
15 Mar 2005
Xen is a virtualization technology available for the Linux™ kernel that lets you enclose and test new upgrades as if running them in the existing environment but without the worries of disturbing the original system. The author shows you how to install Xen using Fedora Core, but once installed, everything works the same in Xen on any distribution. Take a look at virtualization on Linux and see the benefits of having a sandbox for testing new software, as well as a playground for running multiple virtual machines on the same Linux box.

reference (http://www-128.ibm.com/developerworks/linux/library/l-xen/?pa--ca=dgr-lnxw02aXenTest)

Regards

texasducod
24th November 2006, 12:45 AM
I'm having a problem booting the "xen" kernel, it just goes to a black screen right after Starting Dev at boot. However if I choose the non xen kernel it boots fine...where should I look for answers?

Does this mean my system is on it's way down and I'll have to do another re-install soon? I hope not.
or does it just mean that I cant run software in that "xen sandbox" any longer? What exactly is the "sandbox"?

marko
24th November 2006, 01:38 AM
Bryan Clark (bclark@redhat.com), Interaction Designer, Red Hat
15 Mar 2005
Xen is a virtualization technology available for the Linux™ kernel that lets you enclose and test new upgrades as if running them in the existing environment but without the worries of disturbing the original system. The author shows you how to install Xen using Fedora Core, but once installed, everything works the same in Xen on any distribution. Take a look at virtualization on Linux and see the benefits of having a sandbox for testing new software, as well as a playground for running multiple virtual machines on the same Linux box.

reference (http://www-128.ibm.com/developerworks/linux/library/l-xen/?pa--ca=dgr-lnxw02aXenTest)

Regards

Not everything works fine in Xen, powernow under AMD64 doesn't work on Xen
Mark

2541
27th November 2006, 03:43 AM
Not everything works fine in Xen, powernow under AMD64 doesn't work on Xen
Mark

Hi marko!

Is this the reason for my Athlon64 machine telling me it cannot adjust the cpu frequency when running a xen-kernel? It keeps the frequency to 801 mhz.

thanks 2541

marko
27th November 2006, 04:40 AM
2541:

Yes, You'll see a message about a cpu frequency problem
in the xterm. On my machine is was bad enough it was
hard to shut down because I couldn't see what I was typing.
I changed my /etc/rc.d/rc.local to figure out if the kernel is xen
and only load powernow if it's not running a xen kernel:


#!/bin/sh
# rc.local
# This script will be executed *after* all the other init scripts.
# You can put your own initialization stuff in here if you don't
# want to do the full Sys V style init stuff.

touch /var/lock/subsys/local

UCMD="`uname -r`"
RC=`echo "$UCMD" | grep 'xen' | wc -c`
if [ $RC -eq 0 ]
then # if not xen, then allow powernow
modprobe cpufreq_ondemand
echo "ondemand" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo "ondemand" > /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor
fi


for the above to work, don't use cpuspeed (turn off cpuspeed via command
chkconfig cpuspeed off ). In the rc.local file above I'm loading the ondemand
governor module directly .

Mark

2541
27th November 2006, 05:45 AM
I changed my /etc/rc.d/rc.local the way you suggest and turned off cpuspeed, but the cpu frequency still is fixed at 801 mhz when booting into xen-kernel.

marko
27th November 2006, 06:14 AM
I changed my /etc/rc.d/rc.local the way you suggest and turned off cpuspeed, but the cpu frequency still is fixed at 801 mhz when booting into xen-kernel.

Yeah, my "fix" doesn't fix the problem, it just makes sure Fedora doesn't try
to run cpu throttling when the kernel is xen so I avoid the kernel freaking out
about the frequency and also makes sure it does do powernow when it's
ok (i.e. not a Xen kernel)

The only thing that will allow power throttling in Xen is if the
xensource coders can put the support in.

BTW, you do know that the rc.local script will only run at boot time
right?

Oh yeah, also, the rc.local script I showed is only appropriate for a dual
core or dual cpu computer (note the extra "echo" to cpu1 ). On
a single core pc you'd just use one echo statement

Mark

2541
27th November 2006, 06:18 AM
The only thing that will allow power throttling in Xen is if the
xensource coders can put the support in.

Mark
Thanks a lot for your explanation, Mark.

2541