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.

Enable CAN Drivers

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

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: 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.