Add imex support

[klueska]

docker run -it \
        -e NVIDIA_IMEX_CHANNELS=0,1,2047 \
        -e NVIDIA_VISIBLE_DEVICES=0 \
        ubuntu:22.04 bash -c "ls -la /dev/nvidia*"
crw-rw-rw- 1 root root 504,   0 Jan 18 12:59 /dev/nvidia-uvm
crw-rw-rw- 1 root root 504,   1 Jan 18 12:59 /dev/nvidia-uvm-tools
crw-rw-rw- 1 root root 195,   0 Jan 18 12:59 /dev/nvidia0
crw-rw-rw- 1 root root 195, 255 Jan 18 12:59 /dev/nvidiactl
 
/dev/nvidia-caps-imex-channels:
total 0
drwxr-xr-x 2 root root       100 Jan 18 21:32 .
drwxr-xr-x 6 root root       460 Jan 18 21:32 ..
crw-rw-rw- 1 root root 508,    0 Jan 18 19:11 channel0
crw-rw-rw- 1 root root 508,    1 Jan 18 19:11 channel1
crw-rw-rw- 1 root root 508, 2047 Jan 18 19:13 channel2047

[elezar]

One comment. I'm willing to hear arguments on consistency vs simplicity.

[klueska]

One comment. I'm willing to hear arguments on consistency vs simplicity.

Yes. I did it for consistency.

[elezar]

LGTM

Remember that we need to backport these and the libnvidia-container changes.

Created:

• Cherry pick 1.14.6 libnvidia-container#243