Xenomai RTNet
Contents
General Information
Xenomai uses the RTNet stack to provide real-time Ethernet. RTNet provides deterministic versions of various protocols (UDP/IP, IMCP, ARP). Xenomai provides several real-time Ethernet drivers, the stack, and various tools. This document explains how to load a real-time Ethernet driver and perform basic tests. The links below will help augment this information as well as discuss programming using the RTnet stack.
Xenomai RTNet
Loading a RTNet driver
As with the other real-time drivers, the Linux driver must be detached from the interface before loading the real-time driver.
For example on IMX6 target, the fec device must be unbound from the Linux driver and attached to the real-time driver.
root@somimx6-xenomai:~# echo 2188000.ethernet > /sys/bus/platform/drivers/fec/unbind
root@somimx6-xenomai:~# echo 2188000.ethernet > /sys/bus/platform/drivers/rt_fec/bind
[ 86.762295] libphy: fec_enet_mii_bus: probed
[ 86.766586] RTnet: registered rteth0
 | Note: The warning posted about the clock when unbinding the Linux fec driver can be ignored. |
Xenomai provides a script to make launching rtnet easier. This will load the appropriate modules and bring up the interface.
root@somimx6-xenomai:~# rtnet -cf /etc/rtnet.conf start
[ 645.330848] initializing loopback...
[ 645.334487] RTnet: registered rtlo[ 645.355662] RTcfg: init real-time configuration distribution protocol
[ 645.375986] RTmac: init realtime media access control[ 645.400419] RTmac/TDMA: init time division multiple access control mechanism
[ 645.499423] rteth0: Freescale FEC PHY driver [Micrel KSZ9031 Gigabit PHY] (mii_bus:phy_addr=2188000.ethernet:01, irq=-1)
[ 645.551954] rteth0: tx link down!.
...
[ 652.497075] rt_fec 2188000.ethernet (unnamed net_device) (uninitialized): Link is Up - 1Gbps/Full - flow control rx/tx
| Note: The rtnet start will wait for slaves to connect. Press ctrl+c if slaves are not connected. |
The rtnet helper script is configured with /etc/rtnet.conf which determines the IP address of the interface and the slave devices.
The real-time driver is also specified in the configuration file so that it does not need to be loaded before starting the script, but the Linux driver still must be disassociated with the interface.
Accessing RTNet driver
Xenomai provides real-time versions of the basic networking utilities including rtifconfig, rtping, rtroute and rtiwconfig.
root@somimx6-xenomai:~# rtifconfig
rteth0 Medium: Ethernet Hardware address: 00:00:00:00:00:00
IP address: 127.0.0.2 Broadcast address: 127.255.255.255
UP BROADCAST RUNNING MTU: 1500
RX packets:14 errors:0 dropped:0 overruns:0 frame:0
TX packets:164476 errors:0 dropped:0 overruns:0 carrier:0
collisions:0
RX bytes:896 (896.0 b) TX bytes:7031954 (6.7 Mb)
rtlo Medium: Local Loopback
IP address: 127.0.0.1
UP LOOPBACK RUNNING MTU: 1500
root@somimx6-xenomai:~# rtroute
Host Routing Table
Hash Destination HW Address Device
00 0.0.0.0 00:00:00:00:00:00 rtlo
01 127.0.0.1 00:00:00:00:00:00 rtlo
02 127.0.0.2 00:00:00:00:00:00 rtlo
3F 127.255.255.255 FF:FF:FF:FF:FF:FF rteth0
root@somimx6-xenomai:~# rtping 127.0.0.1
Real-time PING 127.0.0.1 56(84) bytes of data.
64 bytes from 127.0.0.1: icmp_seq=1 time=25.7 us
64 bytes from 127.0.0.1: icmp_seq=2 time=20.3 us
64 bytes from 127.0.0.1: icmp_seq=3 time=17.3 us
64 bytes from 127.0.0.1: icmp_seq=4 time=17.0 us
64 bytes from 127.0.0.1: icmp_seq=5 time=17.3 us
64 bytes from 127.0.0.1: icmp_seq=6 time=18.7 us
64 bytes from 127.0.0.1: icmp_seq=7 time=17.0 us
^C
--- 127.0.0.1 rtping statistics ---
7 packets transmitted, 7 received, 0% packet loss
worst case rtt = 25.7 us
