Virtual CAN on WSL2

By default, WSL2 does not support Virtual CAN, however it can be enabled by building a custom WSL2 kernel.

This setup assumes you are running within WSL. If you do not have WSL installed, open up a Windows terminal and run:

wsl --install

Step 1: Update the WSL Environment

Run the following commands in your WSL terminal to update your environment and install the required dependencies.

sudo apt-get update -y

Install dependencies

sudo apt install -y dwarves libelf-dev flex bison libssl-dev libncurses-dev bc build-essential make
sudo apt install -y --no-install-recommends wslu

Step 2: Download the WSL2 Linux Kernel

To ensure compatibility, you need the specific kernel version of WSL2.

Check your kernel version:
```
uname -r
```
- Example output: 5.15.153.1-microsoft-standard-WSL2
- Note the version number, as it must match with <your-kernel-version> in step 2, 3, and 4.
Download the kernel source:
- Go to the WSL2 Linux Kernel repository.
- Find and copy the link for the Source code (tar.gz) file matching your kernel version.

Download and extract the file:

wget https://github.com/microsoft/WSL2-Linux-Kernel/archive/refs/tags/linux-msft-wsl-<your-kernel-version>.tar.gz
tar -xf linux-msft-wsl-<your-kernel-version>.tar.gz

Navigate to the extracted folder:

cd WSL2-Linux-Kernel-<your-kernel-version>

Step 3: Configure Kernel Settings

Load current configuration:
```
cat /proc/config.gz | gunzip > .config
```

Prepare the kernel for modules:

make prepare modules_prepare -j $(expr $(nproc) - 1)

Open the configuration menu:
```
make menuconfig -j $(expr $(nproc) - 1)
```
A menu interface should open. Use this to enable the necessary drivers for Virtual CAN.

Step 1

Enable CAN Drivers

Navigate to Networking Support and press Enter.
Select CAN BUS subsystem support by pressing M, then press Enter.

Step 2 Step 3

Enable CAN Device Drivers

Navigate to CAN Device Drivers.
For each driver shown in the screenshot, press M to enable as a module.
Save and exit the configuration menu.

Step 4

Step 4: Compile and Install Kernel Modules

Run the following commands to compile and install the Virtual CAN modules:

make modules -j $(expr $(nproc) - 1)
sudo make modules_install

Then, compile the kernel:

make -j $(expr $(nproc) - 1)

Step 5: Configure WSL to Use the Custom Kernel

Create a symbolic link for the module directory, matching your kernel version:

sudo ln -s /lib/modules/5.15.153.1-microsoft-standard-WSL2+ /lib/modules/5.15.153.1-microsoft-standard-WSL2

Copy the vmlinux file:

Replace <yourwindowsloginname> with your actual Windows username:
```
cp vmlinux /mnt/c/Users/<yourwindowsloginname>/
```
- In Windows File Explorer, you should now see a file named vmlinux.
Configure .wslconfig:

Create a file named .wslconfig in the same directory (i.e. in /mnt/c/Users/<yourwindowsloginname>/) and paste the following to the file:
```
[wsl2]
kernel=C:\\Users\\<yourwindowsloginname>\\vmlinux
```

Step 6: Restart WSL and Verify

In a separate Windows terminal (not WSL), restart WSL:
```
wsl --shutdown
```
Wait ~10 seconds, then check that WSL has no active processes:
```
wsl --list -v
```
Verify the setup by running WSL again, then execute these commands:
```
sudo modprobe can
sudo modprobe can-raw
sudo modprobe vcan
```

If there is no other message, the installation was successful.