Passing through Intel Arc GPU to LXCs for Transcoding

Mon, 01 Jan 0001 00:00:00 +0000

Foreword

I have a Proxmox server where all of my homelab applications lives in, It’s super complicated with a bunch of random things just strung together in a semi-coherent fashion, but it works. I’m currently in the middle of doing a TV-esque broadcasting solution using ersatzTV, which is super cool if you want a continous TV Channel running in Plex. The issue with this however is that it’s a continously running FFMPEG stream, which if you scale it up and add more channels to it, will absolutely hammer your CPU. So I decided to buy a GPU & pass it through to the docker LXC containing it.

Part 1: Mistakes were made

The proxmox server is running a Ryzen 5600G which was originally purchased with the idea of using the intergrated iGPU for Plex transcodes. Obviously that idea didn’t pan out because plex’s AMD GPU Support is severely lacking and it never properly worked, and since I never transcoded anyways because 90% of my streams were Direct Play I decided to just not bother dealing with it.

In my infinite wisdom I thought that running an Intel Arc GPU Would be infinitely easier to deal with & cheaper than a NVIDIA GPU. I Was Wrong.

Part 2: Living with your Mistakes

I quickly figured out that the Arc GPU Support isn’t in Linux native till the 6.1 Kernel, which Proxmox thankfully has as a opt-in option for their kernel. You can opt-in to 6.2 by going to your proxmox host’s Shell, and run the following commands:

Terminal PVE Kernel Update


apt update
apt install pve-kernel-6.2
reboot

and now were in 6.2!

Next we are going to want to figure out the /dev/dri numbers for the GPU, which can be found by running ls -l /dev/dri on your Shell. Below you can see that I got 226, 0 & 226, 128 respectively on mine.

terminal /dev/dri output


root@pve:~# ls -l /dev/dri
total 0
drwxr-xr-x 2 root root 80 Jun 3 11:41 by-path
crw-rw---- 1 root video 226, 0 Jun 3 11:41 card0
crw-rw---- 1 root render 226, 128 Jun 3 11:41 renderD128

Now that we have those numbers we can go ahead and pass it through to the LXC Containers, which you can do by editing /etc/pve/lxc/<id>.conf and appending the following:


lxc.cgroup2.devices.allow: c <numbers found earlier> rwm
lxc.cgroup2.devices.allow: c <numbers found earlier> rwm
lxc.cgroup2.devices.allow: c 29:0 rwm
lxc.mount.entry: /dev/fb0 dev/fb0 none bind,optional,create=file
lxc.mount.entry: /dev/dri dev/dri none bind,optional,create=dir

It should come out like this example config:

crlf Plex LXC Config


arch: amd64
cores: 12
features: mount=nfs;cifs,nesting=1
hostname: plex
memory: 3050
mp0: /mnt/pve/plex,mp=/media/plex
net0: name=eth0,bridge=vmbr0,gw=10.10.10.1,type=veth
onboot: 1
ostype: ubuntu
rootfs: local-lvm:vm-110-disk-0,size=151G
swap: 1536
lxc.cgroup2.devices.allow: c 226:0 rwm
lxc.cgroup2.devices.allow: c 226:128 rwm
lxc.cgroup2.devices.allow: c 29:0 rwm
lxc.mount.entry: /dev/fb0 dev/fb0 none bind,optional,create=file
lxc.mount.entry: /dev/dri dev/dri none bind,optional,create=dir

And once you have that edited you can go ahead and restart the container.

After Restarting you’re going to want to make sure that the User Plex runs under has access to your GPU by running gpasswd -a plex render & gpasswd -a plex video In the container. You’ll know the GPU was properly passthrough (passthroughed?) when you run hwinfo --display (which can be installed with apt-get install hwinfo ) and see this as the output:

terminal hwinfo readout


root@plex:~# hwinfo --display
06: PCI 300.0: 0300 VGA compatible controller (VGA)
[Created at pci.386]
Unique ID: svHJ.28Q6RjwKYw7
Parent ID: GA8e.mr2N3fBJq5F
SysFS ID: /devices/pci0000:00/0000:00:01.1/0000:01:00.0/0000:02:01.0/0000:03:00.0
SysFS BusID: 0000:03:00.0
Hardware Class: graphics card
Model: "Intel VGA compatible controller"
Vendor: pci 0x8086 "Intel Corporation"
Device: pci 0x56a5
SubVendor: pci 0x1849 "ASRock Incorporation"
SubDevice: pci 0x6004
Revision: 0x05
Driver: "i915"
Driver Modules: "i915"
Memory Range: 0xfa000000-0xfaffffff (rw,non-prefetchable)
Memory Range: 0x7c00000000-0x7dffffffff (ro,non-prefetchable)
Memory Range: 0xfb000000-0xfb1fffff (ro,non-prefetchable,disabled)
IRQ: 119 (259700 events)
Module Alias: "pci:v00008086d000056A5sv00001849sd00006004bc03sc00i00"
Config Status: cfg=new, avail=yes, need=no, active=unknown
Attached to: #44 (PCI bridge)
Primary display adapter: #6

Part 3: How I learned to appreciate what I have

Now in Plex you can go ahead and run any video through the WebUI, which should force it to transcode and you can confirm in the dashboard if it’s using your GPU or CPU.

If it’s listing the transcode as Transcode (hw) then congrats! It’s working.

plex on Zexyen's Blog

Passing through Intel Arc GPU to LXCs for Transcoding

Foreword

Part 1: Mistakes were made

Part 2: Living with your Mistakes

Part 3: How I learned to appreciate what I have