5.2 KiB
can-j1939 kernel module installation
Problem
You already have can0 or vcan0 up and working, can-utils downloaded and compiled to ~/can/can-utils and you can send and receive frames without problems. However, when you want to bring up can-j1939 you get error like this:
avra@vm-debian:~/can/can-utils$ sudo modprobe can-j1939
modprobe: FATAL: Module can-j1939 not found in directory /lib/modules/5.7.0.0.bpo.2-amd64
and also this:
avra@vm-debian:~/can/can-utils$ testj1939
testj1939: socket(j1939): Protocol not supported
Solution
Above errors mean that can-j1939 was not enabled in your kernel and you need to compile it manually. There are several ways to do it. Any Linux kernel since 5.4 has can-j1939 module, but you will probably want to install fresher version, which leads to downloading kernel sources, enabling can-j1939 module, recompiling kernel and installing it. I will be using Debian 10.5 x64 (buster testing) virtual machine.
1. Download kernel source
We will download Debian patched kernel 5.8. First update your sources
avra@vm-debian:~$ sudo apt update
and then see if what Debian pathed kernel source versions are available
avra@vm-debian:~$ apt-cache search linux-source
linux-source-4.19 - Linux kernel source for version 4.19 with Debian patches
linux-source - Linux kernel source (meta-package)
linux-source-5.4 - Linux kernel source for version 5.4 with Debian patches
linux-source-5.5 - Linux kernel source for version 5.5 with Debian patches
linux-source-5.6 - Linux kernel source for version 5.6 with Debian patches
linux-source-5.7 - Linux kernel source for version 5.7 with Debian patches
linux-source-5.8 - Linux kernel source for version 5.8 with Debian patches
If kernel 5.8 does not show in your linux-sources list (it shows in mine since I have already upgraded stock 4.19 kernel to backported 5.7), then you will need to add backports to your sources list. Here is how my /etc/apt/sources.list looks like (you will need to append at least last line to yours):
deb http://security.debian.org/debian-security buster/updates main contrib
deb-src http://security.debian.org/debian-security buster/updates main contrib
deb http://deb.debian.org/debian/ buster main contrib non-free
deb-src http://deb.debian.org/debian/ buster main contrib non-free
deb http://deb.debian.org/debian buster-backports main contrib non-free
After adding backports try sudo apt update again, and apt-cache search linux-source should now show kernel 5.8 in the list, so you can install it's source package
sudo apt install linux-source-5.8
and unpack it
avra@vm-debian:/usr/src$ cd /usr/src
avra@vm-debian:/usr/src$ sudo tar -xaf linux-source-5.8.tar.xz
avra@vm-debian:/usr/src$ cd linux-source-5.8
2. Add can-j1939 module to kernel
First we need some packages for menuconfig
sudo apt-get install libncurses5 libncurses5-dev
copy and use our old configuration to run menuconfig
avra@vm-debian:/usr/src/linux-source-5.8$ sudo cp /boot/config-$(uname -r) .config
avra@vm-debian:/usr/src/linux-source-5.8$ sudo make menuconfig
where we enable SAE J1939 kernel module as shown
- Networking Support
- Can bus subsystem support
- <M> SAE J1939
Now edit /usr/src/linux-source-5.8/.config, find below key and change it as this
CONFIG_SYSTEM_TRUSTED_KEYS=""
and save it.
3. Compile and install kernel and modules
We will have to download necessary packages
sudo apt install build-essential libssl-dev libelf-dev bison flex
compile kernel (using threads to make it faster)
avra@vm-debian:/usr/src/linux-source-5.8$ sudo make -j $(nproc)
install
avra@vm-debian:/usr/src/linux-source-5.8$ sudo make modules_install
avra@vm-debian:/usr/src/linux-source-5.8$ sudo make install
and update grub
avra@vm-debian:/usr/src/linux-source-5.8$ sudo update-grub
avra@vm-debian:/usr/src/linux-source-5.8$ sudo reboot
Check if installation is correct with
sudo modprobe can-j1939
and if you get no error then you can enjoy can-j1939. If you get some error then you might check if this alternative command works:
sudo insmod /lib/modules/5.8.10/kernel/net/can/j1939/can-j1939.ko
If it does then all you need to do is
sudo depmod -av
reboot once, and modprobe command from the above should finally work now.
4. Install headers if needed
You can have a problem with header file, to check that go in the file /usr/include/linux/can.h
nano /usr/include/linux/can.h
If in the struct sockaddr_can you don’t see j1939, then header files did not upgrade, so you need to do this manually
sudo cp /usr/src/linux-source-5.8/include/uapi/linux/can.h /usr/include/linux/can.h
sudo cp /usr/src/linux-source-5.8/include/uapi/linux/can/j1939.h /usr/include/linux/can/
This is the minimum for compiling some J1939 code, but you might want to upgrade other header files as well. That's up to you. Enjoy!