enumerate/0 does not seem to work in WSL

[ejpcmac]

Setup

• Version: 1.2.0
• OS: Windows (WSL)
• Platform: PC

Description

When a serial port is visible as COM5 on Windows, it is accessible as /dev/ttyS5 in the WSL. After ensuring access rights are OK, it is possible to open the connection with nerves_uart:

iex> {:ok, uart} = Nerves.UART.start_link
{:ok, #PID<...>}
iex> Nerves.UART.open(uart, "/dev/ttyS5")
:ok

However, it is not enumerated properly.

Expected Behavior

Nerves.UART.enumerate/0 should return a list of available serial ports.

Actual Behavior

Nerves.UART.enumerate/0 always returns %{}, even if a device is connected.

Steps to Reproduce the Problem

1. Setup a project with nerves_uart in WSL.

2. Connect a device and get its COM port in the device manager on Windows.

3. In the WSL shell, do:

    $ sudo chmod 666 /dev/ttySx
   

   where x is the COM port number in COMx.

4. Assert the communication works properly.

5. Try to enumerate the ports with nerves_uart.

[fhunleth]

Thanks for the report! I've never tried nerves_uart in WSL. This is good to know that there's a gap. I'll add it to my list of things to look at. If you have any insight into getting this to work, I'd certainly appreciate it.

[ejpcmac]

I’ve tried this at work on a colleage’s PC who needed a small tool I’ve developed: it was my first time in WSL. I thought it would be simpler to setup as I use Nix to handle the environment and WSL is expected to behave as Linux, but heh, that’s Windows. I’m not completely surprised in the end. Except this, all seems to work properly.

If I find something interesting I’ll let you know or provide a patch.

[michaelkschmidt]

~~Do the serial ports actually work from WSL? I thought those were all "dummy" files at the moment~~

Sorry I should have read closer. That is cool that the serial ports are actually working

[ejpcmac]

@michaelkschmidt Reading this article from Microsoft, it seems it is. I’ve been able to get a :ok from Nerves.UART.open/2 after chmod-ing. I’ve not tried yet to actually communicate with the device as it is a custom protocol and it was on a colleage’s computer who had to left. If I can manage to get some time on it tomorrow, I’ll try to:

1. actually communicate with the device by selecting the port by hand in my custom protocol library,
2. look at the contents of /sys/class/tty to see if there is some differences with the real Linux one.

[jmerriweather]

I can confirm that the serial ports work properly from WSL. I don't use Nerves.UART.enumerate from WSL as it doesn't return anything