[asterisk-dev] ztxen a zaptel timer for XEN virtual domains

[Michael Cargile]

In order to get Asterisk to work in our XEN virtual domains we created
ztxen. This is currently just ztdummy with the RTC stuff removed. We
created versions for both 1.2.17.1 and 1.4.2.1 (though they would
probably work with some earlier versions). You however do need to have
your kernel compiled with the timer interrupt set to 1000Hz for these to
work. 

We have not done very extensive testing with them at present, just
placed a few phone calls while the system was under load and listened to
a few recordings. The domU domains we used this with were both using the
2.6.18 kernel as well as the dom0 domain. One had the 1.2.17.1 asterisk
version and the other had 1.4.2.1. We plan on doing more extensive
testing with them in the near future as we are going to be creating a
VICIDIAL domU which uses a number of MeetMes as well as IAX trunks
(though this will probably only use the 1.2.17.1 version of asterisk).

The main reason to create a new modules for it was that we plan in the
future to actually rework the whole module so that if you load it in
your dom0 domain as well as your domU domains it would take any zaptel
timing source on the dom0 domain and pass it to the domU domains. This
way they would all be running off the same timing source and would be
far more accurate. It would also work with kernels that have the kernel
interrupt timer set to something other than 1000Hz. This seemed far more
elegant than reworking ztdummy to just check if it is being compiled in
a domU domain and if so not use the realtime clock.

You can find the patches and the bug this is fixing here:
http://bugs.digium.com/view.php?id=9592

We would appreciate any ideas, suggestions, critisism, hatemail, death
threats, ... that anyone has regarding ztxen in its current or future
form.

Michael Cargile
Explido Software
http://www.explido.us