Setting Up Xen Console in Later Versions of Ubuntu Without /etc/inittab

Posted by Tres Fri, 25 Apr 2008 10:03:00 GMT

After Edgy, Ubuntu (6.10) replaced init with upstart. Upstart uses files located in /etc/event.d/ to do what old /etc/inittab entries used to do.

Taking a peek in /etc/event.d/ you’ll see that different run levels are represented by different files. In addition, tty entries are maintained here.

If you’re running Xen, and are having problems with your console access, you’ll need to create /etc/event.d/xvc0 and insert the following:

# xvc0 - getty
#
# This service maintains a getty on xvc0 from the point the system is
# started until it is shut down again.

start on runlevel 2
start on runlevel 3

stop on runlevel 0
stop on runlevel 1
stop on runlevel 4
stop on runlevel 5
stop on runlevel 6

respawn
exec /sbin/getty 38400 xvc0

If you want to retain the ability to hop into the domU without needing to authenticate, make sure that you bypass getty login and spawn a shell:

exec /sbin/getty -n -l /bin/bash 38400 xvc0 

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SSH Doesn't Start on Ubuntu error: PRNG is not seeded

Posted by Tres Fri, 25 Apr 2008 06:45:00 GMT

If you’re trying to start up an Ubuntu environment and seeing

 * Starting OpenBSD Secure Shell server sshd   PRNG is not seeded

when Ubuntu tries starting OpenSSH, make sure that the /dev/random and /dev/urandom entries have read+write permissions for user,group and other.

chmod 666 /dev/urandom /dev/random

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Ubuntu Gutsy Issues on Xen After apt-get upgrade

Posted by Tres Fri, 21 Dec 2007 12:16:00 GMT

After doing an apt-get upgrade on a Gutsy VM recently, I found that ye olde 4gb seg fixup messages had found their way back into dmesg and were all over the console. I quickly apt-get install libc6-xen only to be told that it didn’t exist…

Hmm…

A little investigating and I found that Gutsy didn’t ship with Xen libc, and as of this writing, they are still listed as Proposed.

So the choice was pretty clear, either mv /lib/tls or downgrade the libc we just upgraded to (libc6-xen 2.6.1-1ubuntu10) so it matched with the available lib6c xen package (libc6-xen 2.6.1-1ubuntu9). Personally, I think having the package installed is the right way to go, so I did:

 apt-get remove libc6
 apt-get install libc6=2.6.1-1ubuntu9 libc6-xen=2.6.1-1ubuntu9

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Fixing 4gb seg fixup in Dapper Ubuntu LTS

Posted by Tres Tue, 18 Dec 2007 03:36:00 GMT

Later versions of Ubuntu can be fixed with the easy

apt-get install libc6-xen

But when you run this on 6.06 LTS, the package is unavailable. In order to fix this problem, you just need to do this:

 echo 'hwcap 0 nosegneg' > /etc/ld.so.conf.d/libc6-xen.conf && ldconfig

Of course, any processes that were started before this fix was made will still write the following to syslog:
4gb seg fixup, process xxxx(pid xxxx), cs:ip 73:xxxxxxxx

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Install Ubuntu 7 on a 800X600 Screen

Posted by Tres Wed, 13 Jun 2007 06:57:00 GMT

Trying to install Ubuntu on a new Dell Dimension today I found 1024x768 isn’t available. This makes it impossible to unstall Ubuntu 7 because the installer window is larger than the viewable space. The next buttons aren’t visible.

Changing font size didn’t work.

Rebooting with the monitor disconnected didn’t work.

My co-worker Pierre clued me in to the answer: hold down alt and drag the installer window with the mouse so the buttons become visible.

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