systemd service units and udev rules for managing the AXIA - ALSA soundcard driver for Livewire services.
Paravel Systems offers an AXIA - ALSA
Soundcard Driver for
Livewire (also
known as Axia IP Audio Driver for Linux) which consists out of a Linux kernel
module (snd-axia) and three related daemons (axialwrd, axiaadvd and
axiagpr).
The axia-alsa CentOS
RPM provides a
SysV-style init script (axiad) and an auto-generated systemd service unit
wrapper (axiad.service). Apart from being only a wrapper around the
SysV-style init script, everything is bundled into one script (module loading,
device node creation and the start of the three daemons). Furthermore
the daemons will all be started with root privileges and the startup options
are hard coded into the init script.
These were the reasons and main motivations for re-creating the start-up of the services in a more modern and flexible fashion.
- Dedicated systemd services (no SysV wrapper) with configurable startup options.
- One systemd service unit per service
axialwrd.service- Axia Livewire Routing Daemonaxiaadvd.service- Axia Advertising Daemonaxiagpr.service- Axia GPIO Bridge for Livewire/Control Surface control
snd-axiaKernel module loading via standard systemd modules-load.d mechanism.- Automatic
/dev/axia0device node creation via udev upon module loading - Minimization of
rootprivileges - firewalld service file (for IGMP and Livewire Routing Protocol)
A valid serial number (license) for the Axia IP-Audio Driver for Linux from Paravel Systems is required.
The systemd service units and udev rules are packaged for CentOS 7 and are available on Radio RaBe's Audio Packages for Enterprise Linux repository. They can be installed as follows:
# Install the RaBe APEL repository configuration
curl -o /etc/yum.repos.d/home:radiorabe:audio.repo \
http://download.opensuse.org/repositories/home:/radiorabe:/audio/CentOS_7/home:radiorabe:audio.repo
# Import the Paravel-Broadcast GPG key
rpm --import \
http://download.paravelsystems.com/CentOS/7com/RPM-GPG-KEY-Paravel-Broadcast
# Install the Paravel-Commercial repository configuration
curl -o /etc/yum.repos.d/Paravel-Commercial.repo \
http://download.paravelsystems.com/CentOS/7com/Paravel-Commercial.repo
# Install the required packages (axia-alsa-cli contains the lwlicense command)
yum install systemd-axia-alsa axia-alsa-cli
# Reload the systemd manager configuration
systemctl daemon-reload
# Register your license
lwlicense <SERIAL-NUMBER>Afterwards, reboot your system or manually load the kernel module (modprobe snd-axia), then follow the Usage section.
To install the files manually, use the provided Makefile and set
the prefix to / (which will install the files directly into the root of your
system):
# Install all files
make prefix=/ install
# Create the axia service user and group
userName='axia'
useradd --comment "${userName} system user account" \
--home-dir /dev/null \
--no-create-home \
--system \
--shell /sbin/nologin \
--user-group \
"${userName}"
# Import the Paravel-Broadcast GPG key
rpm --import \
http://download.paravelsystems.com/CentOS/7com/RPM-GPG-KEY-Paravel-Broadcast
# Install the Paravel-Commercial repository configuration
curl -o /etc/yum.repos.d/Paravel-Commercial.repo \
http://download.paravelsystems.com/CentOS/7com/Paravel-Commercial.repo
# Install the required axia-alsa packages
yum install axia-alsa axia-alsa-cli
# Reload the systemd manager configuration
systemctl daemon-reload
# Register your license
lwlicense <SERIAL-NUMBER>Afterwards, reboot your system or manually load the kernel module (modprobe snd-axia), then follow the Usage section.
The axia-alsa kernel module and its related /dev/axia0 device node should
be automatically loaded and created upon boot. You can check that with the
following commands.
Check that the module was loaded:
lsmod | grep snd_axiasnd_axia 24539 2
snd_pcm 106416 2 snd_axia
snd 83432 8 snd_timer,snd_pcm,snd_seq,snd_seq_device,snd_axia
Check that the device node was created by udev
ls -la /dev/axia0crw-r--r--. 1 root root 247, 0 Sep 11 22:09 /dev/axia0
The axia-alsa kernel module parameters (such as the number of virtual
livewire devices) can be changed within /etc/modprobe.d/snd-axia.conf
In case you have a local firewall active, make sure that you allow at least the
IGMP protocol. This is required for IGMP
snooping to work and allows the axialwrd daemon to maintain multicast
subscriptions of the audio and sync streams.
For remote control of the audio routes via the Livewire Routing Protocol, the
TCP port 93 needs to be allowed as well.
If you use firewalld, the required rules can be added via the included firewalld service file:
# Replace YOUR-ZONE with your actual zone name or omit --zone= to use the
# default zone
firewall-cmd --permanent --zone=YOUR-ZONE --add-service=axialwrd
firewall-cmd --reloadThis will add the following iptables/netfiler rules:
-A IN_YOUR-ZONE_allow -p tcp -m tcp --dport 93 -m conntrack --ctstate NEW -j ACCEPT
-A IN_YOUR-ZONE_allow -p igmp -m conntrack --ctstate NEW -j ACCEPT
Consider restricting access to the Livewire Routing port (tcp/93) to a specific management IP address or range.
The three Axia daemons can be managed with the following commands.
# Start the axialwrd service
systemctl start axialwrd.service
# Stop the axialwrd service
systemctl stop axialwrd.service
# Restart the axialwrd service
systemctl restart axialwrd.service
# Get the status of the axialwrd service
systemctl status axialwrd.service
# Show log messages of the axialwrd service
journalctl -u axialwrd.service
# Tail the log messages of the axialwrd service
journalctl -u axialwrd.service -f# Start the axiaadvd service
systemctl start axiaadvd.service
# Stop the axiaadvd service
systemctl stop axiaadvd.service
# Restart the axiaadvd service
systemctl restart axiaadvd.service
# Get the status of the axiaadvd service
systemctl status axiaadvd.service
# Show log messages of the axiaadvd service
journalctl -u axiaadvd.service
# Tail the log messages of the axiaadvd service
journalctl -u axiaadvd.service -f# Start the axiagpr service
systemctl start axiagpr.service
# Stop the axiagpr service
systemctl stop axiagpr.service
# Restart the axiagpr service
systemctl restart axiagpr.service
# Get the status of the axiagpr service
systemctl status axiagpr.service
# Show log messages of the axiagpr service
journalctl -u axiagpr.service
# Tail the log messages of the axiagpr service
journalctl -u axiagpr.service -fThe startup options for all three Axia daemons can be changed within the
systemd environment
file
located at /etc/axia/systemd-env.conf. Refer to the daemon's respective
--help output for a list of supported startup options and remember to restart
the respective system service unit after making a change to this file.
The following example startup configuration, instructs axialwrd and axiaadvdto use the eth1 network interface rather than the default of eth0:
# Systemd environment file for the Axia services
# Axia Livewire Routing Daemon (axialwrd) startup options, see
# 'axialwrd --help' for supported options.
AXIALWRD_OPTS="-i eth1"
# Axia Advertising Daemon (axiaadvd) startup options, see 'axiaadvd --help' for
# supported options.
AXIAADVD_OPTS="-if eth1"
Zabbix users can import the Zabbix Axia ALSA Soundcard Driver for Livewire monitoring templates in order to monitor the various components of the Axia IP Audio Driver for Linux.
The following commands might help on debugging.
Systemd service units status:
systemctl status axialwrd.service
systemctl status axiaadvd.service
systemctl status axiagpr.service
systemctl status sys-module-snd_axia.deviceCheck that the kernel module has been loaded and the device node was created.
udev sysfs info:
udevadm info /sys/module/snd_axiaP: /module/snd_axia
E: DEVNAME=/dev/axia0
E: DEVPATH=/module/snd_axia
E: MAJOR=247
E: MINOR=0
E: NAME=axia0
E: SUBSYSTEM=module
E: TAGS=:systemd:
E: USEC_INITIALIZED=18014
udev add event test:
udevadm test -a add /sys/module/snd_axia[...]
Reading rules file: /usr/lib/udev/rules.d/90-snd-axia.rules
[...]
IMPORT 'snd-axia.sh --env' /usr/lib/udev/rules.d/90-snd-axia.rules:11
starting 'snd-axia.sh --env'
'snd-axia.sh --env'(out) 'NAME=axia0'
'snd-axia.sh --env'(out) 'MAJOR=247'
'snd-axia.sh --env'(out) 'MINOR=0'
'snd-axia.sh --env'(out) 'DEVNAME=/dev/axia0'
'snd-axia.sh --env' [2793] exit with return code 0
RUN 'snd-axia.sh --mknod' /usr/lib/udev/rules.d/90-snd-axia.rules:11
created db file '/run/udev/data/+module:snd_axia' for '/module/snd_axia'
ACTION=add
DEVNAME=/dev/axia0
DEVPATH=/module/snd_axia
MAJOR=247
MINOR=0
NAME=axia0
SUBSYSTEM=module
TAGS=:systemd:
USEC_INITIALIZED=18014
run: 'snd-axia.sh --mknod'
Unload module index
Unloaded link configuration context.
udev helper script tests:
# Create udev env vars
/usr/lib/udev/snd-axia.sh --env
# Create the /dev/axia0 device node
/usr/lib/udev/snd-axia.sh --mknod
# Remove the /dev/axia0 device node
/usr/lib/udev/snd-axia.sh --rmnodNetwork status and debugging:
# List socket binding
ss -apn | grep -i axia
# List socket bindings on legacy systems
netstat -anp | grep axia
# Firewall (if active)
firewall-cmd --zone <ZONE> --list-all
iptables -nvL
# Display multicast group membership information for IPv4
ip -4 maddr
# Display multicast group membership information for IPv4 on legacy systems
netstat -gn4
# Package dump
tcpdump -i <DEVICE> -nn -vvv 'net 239.0.0.0/8'systemd-axia-alsa is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, version 3 of the License.
Copyright (c) 2017 - 2018 Radio Bern RaBe