[PVE-User] USB device passthrough

Florian Heiber florian at heiber.me
Wed Dec 29 10:55:26 CET 2021

Hi all,

I’m trying to pass multiple USB devices from my host through into my container. I’ve followed a few tutorials ([1], [2]) that describe the process, but I can’t get it to work.

What have I done?

I have connected the USB devices to my host. I can confirm that they work via /dev/ttyUSB0, etc. I created a udev rule to consistently have them available as /dev/reader0, etc. I can also confirm that I can use those aliases as if I was using the original device. I consider this a success.

I updated the container’s configuration at, in this case, /etc/pve/lxc/109.conf to include my mount points:

lxc.cgroup.devices.allow: c 7:* rwm
lxc.mount.entry: /dev/reader0 dev/reader0 none bind,optional,create=file

After a reboot of the container, the device appears as configured. Unfortunately, I looks like I have some issues with my permissions. When I try to print out the data coming from the reader, I only see a 

florian at datalogger:~$ cat /dev/reader0 | od -tx1
cat: /dev/reader0: Permission denied

This does, however, work as expected when I run this on the host itself.

Does anyone see what I’m missing here? One point I’m not too sure about is the major part in the lxc.cgroup.devices.allow line. I suppose it should reflect the major part of the device I'm trying to expose, but some tutorials used the one of the original device (/dev/ttyUSB0 in my case, 188) here.

Thank you for your time!

All the best,
– Florian

[1]: https://drozmotix.github.io/languages/en/BasicSetup/03.ProxmoxLXC.html#what-is-lxc
[2]: https://deviant.engineer/2016/11/lxc-passthrough/

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