{"id":150,"date":"2009-02-03T18:29:19","date_gmt":"2009-02-04T01:29:19","guid":{"rendered":"http:\/\/www.kernelcrash.com\/blog\/?p=150"},"modified":"2009-06-23T16:32:34","modified_gmt":"2009-06-23T23:32:34","slug":"openvz-and-asterisk-and-pae","status":"publish","type":"post","link":"https:\/\/www.kernelcrash.com\/blog\/openvz-and-asterisk-and-pae\/2009\/02\/03\/","title":{"rendered":"OpenVZ and Asterisk and PAE"},"content":{"rendered":"

This post started out as a simple howto for installing Asterisk<\/a> in an OpenVZ<\/a> container on Debian Lenny<\/a>. It all started out well, as a test box I used my core2duo server running Debian Lenny, did an apt-get of the openvz kernel image that is already in the Lenny standard repository, downloaded an OpenVZ template for\u00a0 a minimal Lenny virtual machine (VM), got a VM running, installed asterisk using apt-get inside the VM, got it configured, then worked out how to install the zaptel modules (usiing the debian repository’s zaptel-source) in the host machine using module-assistant, and then getting the zaptel stuff recognised within the VM. And it all worked.<\/p>\n

However, setting it up on the core2duo box was just a test. I really wanted to set it up on my old Thinkpad T42. It’s been gathering dust since I bought the Macbook, and it seemed such a shame to have it doing nothing. I’ve had an old Thinkpad 600X running Asterisk for a while now. It runs natively (ie. not in a VM) and does the job, but it has a hand compiled kernel and Asterisk … and that kind of set up tends to put me off doing proper updates on it. Hence why I was liking Debian Lenny; modern kernel and Asterisk 1.4.x in the standard repository. And the T42 had a bit of horsepower with a 1GB of RAM and a 100GB drive, so I thought something like Asterisk could be virtualised on it.<\/p>\n

So step 1, install Lenny from CD on the T42 and ‘apt-get update’ , ‘apt-get upgrade’, then step 2 ; install the openvz kernel image;<\/p>\n

apt-get install linux-image-2.6.26-1-openvz-686<\/p><\/blockquote>\n

And reboot … and nothing. It would not boot. Obviously my Thinkpad did not like this kernel. It turns out that the Debian Lenny OpenVZ kernel is compiled with PAE<\/a> support compiled in. A core2duo has PAE support. The Pentium M in the Thinkpad does not support PAE.<\/p>\n

So what to do? I could go on about the other virtualisation techniques I tried here … but ultimately I liked the idea of OpenVZ; Simple kernel mod, light overhead, don’t need dedicated raw files on disk for VMs. I also liked that Lenny had a standard OpenVZ kernel in it’s repository, which ultimately meant ‘easy kernel updates’.<\/p>\n

So I thought I’d have\u00a0 a go at trying to recompile the Debian OpenVZ kernel with PAE turned off … in a supportable way. To me the easy way is to get a vanilla kernel from kernel.org, and add the patches from openvz.org. But I wanted to have a kernel closely approximating the latest apt-get’able Debian OpenVZ kernel.<\/p>\n

I’ve used make-kpkg to make my own debian kernels before, but that didn’t really work in this case.<\/p>\n

So here’s what I did (I got a lot of ideas from this post about Xen without PAE<\/a>);<\/p>\n

# get the source
\ncd \/usr\/src
\napt-get source linux-image-2.6.26-1-openvz-686<\/p><\/blockquote>\n

Now you should end up with a \/usr\/src\/linux-2.6-2.6.26 directory. It looks like a normal kernel extraction directory, but with a debian directory.<\/p>\n

cd \/usr\/src\/linux-2.6-2.6.26\/debian\/config\/i386
\nvi config.686-bigmem<\/p><\/blockquote>\n

Now I just searched for PAE in the partial config file and turned it off, as well as disabled the 64GB setting and enabled the 4GB one. Mine looks like this:<\/p>\n

CONFIG_HIGHMEM4G=y
\nCONFIG_HIGHMEM64G=n
\n## end choice
\nCONFIG_X86_PAE=n<\/p><\/blockquote>\n

Save that. Now do all the steps to apply patches, build the config, and compile to generate the kernel image and headers deb<\/p>\n

cd \/usr\/src\/linux-2.6-2.6.26
\nfakeroot debian\/rules debian\/build debian\/stamps<\/p>\n

# Removing these ABI files below is a cheap hack workaround to errors that are normally produced at the end of the compile<\/p>\n

rm debian\/abi\/2.6.26-1\/*
\nfakeroot make -f debian\/rules.gen binary-arch_i386_openvz_686<\/p><\/blockquote>\n

That last fakeroot command will take ten bazillion years to complete. Once complete you should end up with two deb files in \/usr\/src;<\/p>\n

linux-headers-2.6.26-1-openvz-686_2.6.26-13_i386.deb
\nlinux-image-2.6.26-1-openvz-686_2.6.26-13_i386.deb<\/p><\/blockquote>\n

Now install both of these;<\/p>\n

cd \/usr\/src
\ndpkg -i linux-headers-2.6.26-1-openvz-686_2.6.26-13_i386.deb
\ndpkg -i linux-image-2.6.26-1-openvz-686_2.6.26-13_i386.deb<\/p><\/blockquote>\n

And make sure you have the OpenVZ tools installed;<\/p>\n

apt-get install vzctl<\/p><\/blockquote>\n

And try rebooting<\/p>\n

This time it worked for me.<\/p>\n

And now (finally) we set up a virtual machine and install Asterisk in it.<\/p>\n

Download an OpenVZ template for Lenny from http:\/\/openvz.org\/download\/template\/cache<\/a>;<\/p>\n

debian-5.0-i386-minimal.tar.gz<\/p><\/blockquote>\n

You just put the tar.gz file in \/var\/lib\/vz\/template\/cache (ie. don’t extract it).<\/p>\n

Then its a case of picking a unique id for your VM (eg. 101) and doing\u00a0 something like;<\/p>\n

vzctl create 101 –ostemplate debian-5.0-i386-minimal –config vps.basic
\nvzctl set 101 –onboot yes –save
\nvzctl set 101 –hostname testmachine –save
\nvzctl set 101 –ipadd 10.1.2.3 –save
\nvzctl set 101 –nameserver 1.2.3.4 –save
\nvzctl start 101<\/p><\/blockquote>\n

The VM should start quickly and to get a sort of console you enter;<\/p>\n

vzctl enter 101<\/p><\/blockquote>\n

One thing that confused me initially is how networking works. The basic example above uses venet networking. I wasnt sure whether the IP address I specified should be on a seperate subnet or on the same subnet as my host machine. In the end, I used an IP address that was on the same subnet as my host machine. It doesn’t use brctl style bridging, but it effectively bridges the interface onto your network. I must admit I couldn’t find a decent explanation\/diagram of how OpenVZ networking works.<\/p>\n

Install asterisk in the VM;<\/p>\n

apt-get install asterisk<\/p><\/blockquote>\n

The install worked fine, but because of problems with Music On Hold in the past I wanted to set up ztdummy properly. This can be done.<\/p>\n

In the host machine I installed the zaptel modules per this debian howto<\/a><\/p>\n

apt-get install zaptel-source
\nmodule-assistant prepare
\nmodule-assistant auto-install zaptel<\/p><\/blockquote>\n

Afer you do that, do a ‘modprobe ztdummy’. The first time I tried this it didn’t work, because Lenny had downloaded the ‘official’ package for the OpenVZ kernel headers rather than the one that I generated. If that happens to you, dpkg -r the old package, and then install the headers deb that you created earlier. Then run the auto-install above again and double check that the ztdummy modules inserts cleanly. If you do a dmesg now, you should see something like;<\/p>\n

ztdummy: High resolution Timer started, good to go<\/p><\/blockquote>\n

So that gets ztdummy working from the host machine. We need to make it accessible from within the virtual machine. I looked at the following two howtos;<\/p>\n

http:\/\/wiki.openvz.org\/Asterisk_in_VE_with_debian_stable<\/a>
\nhttp:\/\/wiki.openvz.org\/Asterisk_from_source<\/a> (I just used the vzctl example commands they have)<\/p>\n

The big test of whether the ztdummy stuff is working from inside the virtual machine is to run zttest and hit ctrl-c after a few lines of output. Here’s how mine runs;<\/p>\n

root@lenny:\/# zttest
\nOpened pseudo zap interface, measuring accuracy…
\n99.996582% 99.975983% 99.984177% 99.983887% 99.984070% 99.984467% 99.984375%
\n99.984177% 99.979492% 99.984467% 99.981735% 99.983208% 99.984581% 99.982819% 99.983978%
\n99.982811% 99.977448% 99.983971% 99.983971% ^C
\n— Results after 19 passes —
\nBest: 99.997 — Worst: 99.976 — Average: 99.983484, Difference: 99.983484<\/p>\n

So the only bit remaining for me was to configure asterisk. I just copied files over from my old Asterisk server and got it going. The only issues I had;<\/p>\n