Difference between revisions of "Clean Core"

Revision as of 01:10, 24 August 2007

Introduction

This page is meant to document the efforts to turn the LMCE core into one or more "services" that are automaticly started at boot time. In other words we would like to get rid of the Launch Manager application, and it's dependency uppon a graphic environment, at least for starting a (dedicated) core machine.

Due to the lack of documentation we will have to figure a lot of things out on our own. Please don't be shy to add any related knowledge you have, we don't really know what we're doing, so why should you? At least by adding stuff here we'll be able to build uppon each others experience without having to reverse-engineer the wheel every time. And who knows, one day we might even achieve our common goal.

Runlevels

Runlevels are an easy way to change how the system boots. LinuxMCE uses runlevel 2 for normal operation (depending on the selections you made during installation) and runlevel 1 is used for rescue mode. The runlevels 0 and 6 are used for doing a shutdown or a reboot. Which leaves the runlevels 3, 4 and 5 free for us to experiment with.

Setting the default runlevel

The default runlevel is 2, unless specified otherwise in the /etc/inittab file, here is an example on how to create such a file (it will override an existing one):

cat >/etc/inittab << EOF
# WARNING: Do NOT set the default runlevel to 0 (shutdown) or 6 (reboot).
id:2:initdefault: # LinuxMCE
#id:3:initdefault: # KDE
#id:4:initdefault: # Core
#id:5:initdefault: # Unused
EOF

This specifies a default runlevel 2 (which it already was without this file anyway), you can use your favorite text editor to edit it to your desire when you permanently want to switch.

Selecting a runlevel at boottime

Since changing a text file to switch back and forth every time isn't very comfortable, here is a way to do it from the boot-menu. First we need to replace one of upstart's files, /etc/event.d/rc-default. (It's not a big addition, but I didn't like the way it was written originally, so I just rewrote most of it.)

cat >/etc/event.d/rc-default <<EOF
# rc - runlevel compatibility
#
# This task guesses what the "default runlevel" should be and starts the
# appropriate script.

start on stopped rcS

script
        runlevel --reboot || true


        if grep -q -w -- "-s\|single\|S" /proc/cmdline
        then
                RL="S"
        else
                RL="$(sed -n -e "s/.*runlevel=\([1-5]\).*/\1/p" /proc/cmdline || true)"
        fi

        if [ -z "$RL" -a -r /etc/inittab ]
        then
                RL="$(sed -n -e 's/^id:\([1-5]\):initdefault:.*/\1/p' /etc/inittab || true)"
        fi

        if [ -z "$RL" ]
        then
                RL="2"
        fi

        telinit $RL

end script
EOF

Now edit [i]/boot/grub/menu.lst[/i] with your favorite editor as follows:

Comment out the hiddenmenu option (this will show you the menu without having to press esc)

## hiddenmenu   
# Hides the menu by default (press ESC to see the menu)
#hiddenmenu

Copy the first boot target once for every runlevel you want to be able to start, and modify it to look something like this:

title           LMCE 1.1 (0704) Launch Manager
root            (hd#,#)
kernel          /boot/vmlinuz-2.6.20-15-generic root=UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx ro quiet splash runlevel=2
initrd          /boot/initrd.img-2.6.20-15-generic
quiet
savedefault

title           LMCE 1.1 (0704) KDE
root            (hd#,#)
kernel          /boot/vmlinuz-2.6.20-15-generic root=UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx ro quiet splash runlevel=3
initrd          /boot/initrd.img-2.6.20-15-generic
quiet
savedefault

title Ubuntu, kernel 2.6.20-15-generic

root            (hd#,#)
kernel          /boot/vmlinuz-2.6.20-15-generic root=UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx ro quiet splash 

initrd /boot/initrd.img-2.6.20-15-generic quiet savedefault

to be continued soon...

Known Information

• In Starting CORE software automatically. Beta1.1 bobpaul wrote on June 24, 2007 [1]:

you'll find all of the LinuxMCE scripts in /usr/pluto/bin. 
Two very interesting scripts are Start_X.sh (which I assume you already found?) and StartCoreServices.sh

My guess would be you could disable the Start_X script. 
This can be done from the web interface and goto Advanced: Software: Boot Sequence. 
Untick the box for Start_X. 
Then, manually launch /usr/pluto/bin/StartCoreServices.sh from some init script. 
I think that should do what you originally asked for, but I haven't tried it myself.

• A request for more information on the forum was posted by KingCrab: How does a core system start?. If you don't want to sign up for the wiki or feel uncomfortable editing this page you could leave a message there.

• More to come...

Version Specific Notes

This seems like a good place to add information specificly related to a certain version of LMCE.

LMCE 1.1 RC1

The current test version.

Personal Notes

So... what did you try, and how did it work out?

I've tried the way bobpaul described in his post, but unfortunately working with the Start_X box didn't change anything for me. Then I tried it the "old linux way" ;-) I removed the S99kdm script from /etc/rc2.d, giving me a text login at bootup. Next step was to modify the /etc/rc.local by adding /usr/pluto/bin/StartCoreServices.sh. After next bootup the login web page was up again. This is the point I stopped testing and tried to get more information on startup before moving on... (done with beta2 and rc1)

-- KingCrab

I looked on a dedicated core, but the Start_X box was already unticked in the web interface for the core. So I looked at "/etc/rc2.d/S99kdm" which turned out to be a symlink to a non-existant file. In the end I just rebooted to "rescue" mode and launched "/usr/pluto/bin/StartCoreServices.sh" by hand. After taking controll with "screen -r" I discover that the DCERouter is unable to connect to the MySQL server.

I reboot the machine to single usermode again to have a clean starting point, this time I decide to change to runlevel 3 with the command "telinit 3". LinuxMCE is only fully started in runlevel 2 so there are no screen sessions to attach to except for the "VoiceMailMonitor" one (obviously started by /etc/rc3.d/S99voiceMailMonitor). After launching "/usr/pluto/bin/StartCoreServices.sh" by hand again I see 2 additional screen sessions for "discovery" and "DCERouter", none of the sessions seem to show errors. The script itself however ended with the message "ERROR: Couldn't attach to DCOP server".

The web-admin appears to fully work, and so does booting a diskless Media Director. Storage might not fully work yet though, as there are still 2 pluto related scripts (symlinked) in "/etc/rc2.d" that I haven't started yet, "StorageDevices_SambaRadar.sh" and "StorageDevices_StatusRadar.sh" but I'm not entirely sure if they normally even get started since they don't have the usual S## prefix.

I tested this using a dedicated core installation of LMCE-1.1B2 running under VMWare as described in: Testing with VMWare, which I still had lying around.

-- Zaerc 15:53, 2 August 2007 (MST)

Not entirely unrelated, but I stumbled onto this neat trick. If you have installed your LinuxMCE hybrid as a "A dedicated LMCE System" so that it starts automaticly after boot you can switch to starting LinuxMCE from the desktop icon (and back) with these instructions. For this the otherwise unused runlevel 3 is used. Basicly this hack just activates the backup-config of KDE in another runlevel, and then sets that runlevel as the default, this way it's easy to switch back and forth.

These instructions require root privileges!

1. Change the /etc/rc3.d/S99kdm symlink to point at ../init.d/kdm.saved.
2. Create an /etc/inittab configuration file to start runlevel 3 by default (there should be none to start with, but you may want to check to be certain, if it already exists you can skip this step and edit it as described below).
3. Reboot the machine.

ln -sfv ../init.d/kdm.saved /etc/rc3.d/S99kdm

cat >/etc/inittab << EOF
# WARNING: Do NOT set the default runlevel to 0 (shutdown) or 6 (reboot).
#id:2:initdefault: # LinuxMCE
id:3:initdefault: # KDE
#id:4:initdefault: # Unused
#id:5:initdefault: # Unused
EOF

reboot

You should be greeted by the KDE login screen, after logging in with the user you created during the Kubuntu installation, you should be able to start LinuxMCE with the icon as one normally would after a "Primary used as PC" type of installation.

If you want to change the default runlevel again, simply use your favorite text editor (as root) to uncomment one of the other lines in the /etc/inittab created earlier. WARNING: Do NOT set the default runlevel to 0 (shutdown) or 6 (reboot), if you do your system will either immediately shutdown or reboot! This can be fixed, but just don't do it ok?

I did this on my LinuxMCE-1.1RC1 hybrid installation, which was installed as a dedicated LMCE machine.

-- Zaerc 18:29, 4 August 2007 (MST)

And why stop there? (apart from that it's getting light outside again). I decided to try KingCrabs approach with an other runlevel.

1. replace Startup_Core-Hybrid with StartCoreServices and save the result in a new file.
2. remove the link that starts "kdm" in runlevel 4
3. make a symlink in runlevel 4 to start our modified script

sed -e 's/Startup_Core-Hybrid/StartCoreServices/' /etc/init.d/kdm >/etc/init.d/lmce-core
rm -v /etc/rc4.d/S99kdm
ln -sfv ../init.d/lmce-core /etc/rc4.d/S99lmce-core

Now you can use the /etc/inittab trick described above and reboot. To change the default runlevel back to as it was you set it to runlevel 2, deleting the /etc/inittab file completely should have the same effect (deleting could break non-Kubuntu systems though if they rely on this file).

Not all services might be properly started yet, this is experimental! These start scripts might also still need to be started for full operation:

diff rc2.d/ rc4.d/
Only in rc2.d/: S10powernowd.early
Only in rc2.d/: S23instcheck.sh
Only in rc2.d/: S98LMCEUpdate
Only in rc2.d/: S990start_avwizard
Only in rc2.d/: S99kdm
Only in rc4.d/: S99lmce-core
Only in rc2.d/: S99stop-readahead
Only in rc2.d/: StorageDevices_SambaRadar.sh
Only in rc2.d/: StorageDevices_StatusRadar.sh

After booting a diskless media director I see a bunch of CIFS VFS errors on the console, but I have seen plenty of those before I even got started. The web-admin seems to work, the diskless MD plays media, however X10 lighting and the mobile orbitter on my phone, as well as restarting the core from the UI or web-admin don't seem to work, so were not quite done yet.

In the end I changed the default runlevel back to 2 and everything works as it did before and I can control the lights with the mobile again...

-- Zaerc 22:17, 4 August 2007 (MST)