J1939 Support

[pschichtel]

As "requested" by @JohnLussmyer one of the missing J1939 protocol should be added. I have little to no knowledge about the protocol, so any reference code would be helpful to implement it. I assume it would be similar to the RAW channel.

[JohnLussmyer]

I've been looking into making some changes so I could test things.
So far, I can't build due to the java 8 requirement. openjdk-8-jdk doesn't seem to exist for a Raspberry Pi 4.
Do you think it will work with Java 17 if I remove the check for java 8?

[pschichtel]

I've been looking into making some changes so I could test things.

Awesome!

openjdk-8-jdk doesn't seem to exist for a Raspberry Pi 4.

OpenJDK 8 for aarch64: https://adoptium.net/temurin/releases/?os=linux&arch=aarch64&package=jdk&version=8

Do you think it will work with Java 17 if I remove the check for java 8?

Compilation will most certainly not work in anything >8 because they changed some paths around and I don't think the current build scripts support the newer layout. JavaCAN can run on any JRE >=8 though, it's compiled with jdk 8 to ensure that.

The build infrastructure is centered around cross-building other architectures from x86_64 using dockcross, currently there isn't any way to build JavaCAN with the "host architecture". Dockcross is also only available for x86_64 if I'm not mistaken.

So my recommendation is: Build JavaCAN on an x86_64 machine and transfer the jar over to your raspberry pi.

Is that viable for you?

[JohnLussmyer]

Ok, I finally got a x64 linux box up and running. Everything is installed.
Note that I carefully did NOT change any of your code.
When I ran the full build, I get an error (below). Any ideas?

[INFO] Running tel.schich.javacan.test.util.IsotpListenerTest
[ERROR] Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.058 s <<< FAILURE! -- in tel.schich.javacan.test.util.IsotpListenerTest
[ERROR] tel.schich.javacan.test.util.IsotpListenerTest.testBroker -- Time elapsed: 0.054 s <<< ERROR!
tel.schich.javacan.platform.linux.LinuxNativeOperationException: Unable to write to the socket - errorNumber=11, errorMessage='Resource temporarily unavailable'
at tel.schich.javacan.SocketCAN.write(Native Method)
at tel.schich.javacan.AbstractCanChannel.writeSocket(AbstractCanChannel.java:237)
at tel.schich.javacan.IsotpCanChannelImpl.write(IsotpCanChannelImpl.java:102)
at tel.schich.javacan.test.util.IsotpListenerTest.testBroker(IsotpListenerTest.java:85)

[pschichtel]

Seems like something is off about the ISOTP socket a in the test.

Can you confirm that this works:

1. Open 1. shell and run isotprecv -s 7E0 -d 7E8 vcan0
2. Open 2. shell and run isotpsend -s 7E8 -d 7E0 vcan0 <<< "a"
3. the 1. shell should print 0A

Also please share the output of lsmod | grep can.

[JohnLussmyer]

Shell 1 echoed just fine.

john@Linux-HP:$ isotprecv -s 7E0 -d 7E8 vcan0
0A
john@Linux-HP:$ lsmod | grep can.
vcan 12288 0
can_dev 57344 1 vcan
can_raw 16384 0
can_isotp 28672 0
can_bcm 24576 0
can 24576 3 can_isotp,can_raw,can_bcm
john@Linux-HP:~$

[JohnLussmyer]

I just re-read your README.md - and realized I have no idea what to do for this line of instruction:

•The can-isotp kernel module loaded (Kernel 5.10 with CONFIG_CAN_ISOTP enabled or the out-of-tree module)

[pschichtel]

you have the can_isotp module loaded as shown by your lsmod output, that's why I asked for it.

Which kernel version are you running? (uname -a)

Also:

can you try running the test with the following added after line 69 in file tel/schich/javacan/test/util/IsotpListenerTest.java:

a.configureBlocking(true);
b.configureBlocking(true);

[JohnLussmyer]

john@Linux-HP:~$ uname -a
Linux Linux-HP 6.5.0-14-generic #14~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Mon Nov 20 18:15:30 UTC 2 x86_64 x86_64 x86_64 GNU/Linux

[INFO] Running tel.schich.javacan.test.util.IsotpListenerTest
[ERROR] Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.058 s <<< FAILURE! -- in tel.schich.javacan.test.util.IsotpListenerTest
[ERROR] tel.schich.javacan.test.util.IsotpListenerTest.testBroker -- Time elapsed: 0.054 s <<< ERROR!
tel.schich.javacan.platform.linux.LinuxNativeOperationException: Unable to write to the socket - errorNumber=11, errorMessage='Resource temporarily unavailable'
at tel.schich.javacan.SocketCAN.write(Native Method)
at tel.schich.javacan.AbstractCanChannel.writeSocket(AbstractCanChannel.java:237)
at tel.schich.javacan.IsotpCanChannelImpl.write(IsotpCanChannelImpl.java:102)
at tel.schich.javacan.test.util.IsotpListenerTest.testBroker(IsotpListenerTest.java:87)

[pschichtel]

Ok, do other tests work? E.g. Just delete this one and run the build again

[JohnLussmyer]

Deleted isotplistenertest.java - and the build ran with no errors.

[JohnLussmyer]

Now I get to start writing tests to see if my new code works at all....

[JohnLussmyer]

Question: I just noticed that the Pi 4 uses "Broadcom BCM2711, Quad core Cortex-A72 (ARM v8) 64-bit SoC @ 1.8GHz"
Any chance that the code supports the ARM v8 processor?

[pschichtel]

Isn't still just aarch64? I'd assume the aarch64 build should just work, but I have no hardware to actually test it. Is this just a question or did you actually observe an issue? Architecture auto-detection in Java is difficult on all the different arm variants, so if you use that it might have picked the wrong library.

[JohnLussmyer]

Just a question, since I saw that ArmV6 and V7 were explicit native code supported.

[JohnLussmyer]

And I just tried building the "all-architectures". It got up to:
[INFO] --- exec-maven-plugin:3.1.1:exec (compile-native-riscv32) @ javacan-core ---
Compiling for: riscv32 (dockcross: docker.io/dockcross/linux-riscv32:20231110-9476e91)
....
Copying blob sha256:28469740a38f7f50a08906c874b71b52323ecbab72b05ab940a5891016b73ec9
Error: writing blob: storing blob to file "/var/tmp/storage3447402512/13": happened during read: unexpected EOF
[ERROR] Command execution failed.
org.apache.commons.exec.ExecuteException: Process exited with an error: 125 (Exit value: 125)

I have plenty of disk space.