#1. Fixing device permissions
Since systemd is not running under WSL2 some of the UDEV rules won’t run that set the groups, etc. As a result the devices under /dev/ will all be owned by root still.
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$ ls -al /dev/ttyACM*
crw-rw---- 1 root root 166, 0 May 29 23:14 /dev/ttyACM0
As a temporary fix… Run sudo system udev restart BEFORE plugging in the device (or attaching to WSL). This will ensure that UDEV can make the necessary adjustments. (change the group owner to plugdev)
After the fix.
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$ ls -al /dev/ttyACM*
crw-rw---- 1 root plugdev 166, 0 May 29 23:14 /dev/ttyACM0
Also make sure your user is a member of plugdev. Run groups to check
Making it automatic
Add this to ~/.bashrc
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[ -z "$(pgrep systemd-udevd)" ] && sudo service udev restart &> /dev/null
added in sudo visudo to allow .bashrc (or well anyone) to actually do it.).
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%sudo ALL=NOPASSWD: /usr/sbin/service udev restart
#2. Force udev to fix permissions without unplugging the device
This seems to be enough get the ACLs set…
If AFTER device already attached… re-trigger event
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sudo service udev restart
sudo udevadm trigger -v --name-match=ttyACM0
If BEFORE device attached… this is sufficient
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sudo service udev restart
Alternatively you could cycle the detach/attach cycle manually via usbip
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usbipd.exe wsl detach --hardware-id=2341:0001
usbipd.exe wsl attach --hardware-id=2341:0001
#3. Smart device attachment
Attach if not already attached
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[ -z "$(usbipd.exe wsl list | grep 2341:0001.*Attached)" ] && usbipd.exe wsl attach --hardware-id=2341:0001
OR grep can do the testing for us… slightly different semantics… if we find the device and it is not attached… The other test would try to attach even if the device wasn’t listed.
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usbipd.exe wsl list | grep -q "2341:0001.*Not attached" && \
echo "Attaching" && \
usbipd.exe wsl attach --hardware-id=2341:0001
Crazy one-liner command check for device existence first, and then attach if not already attached.
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$ (usbipd.exe wsl list | grep -q " 2341:0001 " || (echo "Device not found"; false)) && (usbipd.exe wsl list | grep -q "2341:0001.*Not attached" && echo "Device found, but not attached. Attaching..." && usbipd.exe wsl attach --hardware-id=2341:0001 || echo "Device attached")
Broken down…
Check for device existence
Check if already attached
If not attached, attach
Otherwise just report the device attached
#4. WSL Make enhancements
We can build the smart device attachment into a Makefile target and call it from your flash target automatically. Now you don’t have to worry about usbip at all.
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#
# WSL features
#
DEVICE_HWID = 2341:0001
# Attach the device via usb/ip if not already attached
usbip_attach:
@[ -z "$(shell usbipd.exe wsl list | grep $(DEVICE_HWID).*Attached)" ] \
&& echo "Device not attached. Attaching now..." \
&& usbipd.exe wsl attach --hardware-id=$(DEVICE_HWID) \
&& sleep 2 \
|| true
# Flash via windows-based avrdude.exe
flash_win: AVRDUDE = /mnt/c/DEV/AVR/avrdude/avrdude.exe
flash_win: PROGRAMMER_ARGS = -P COM4
flash_win: flash