RaspberryPi 4 - ArchlinuxARM: Can't open device file: /dev/vcio
danieletorelli opened this issue · comments
Hello, I'm experiencing this issue on my RaspberryPi 4 since Archlinux ARM started using those binaries some day ago as /dev/vcio doesn't seem to be created anymore.
Kernel:
Linux alarm 6.2.10-1-aarch64-ARCH #1 SMP PREEMPT_DYNAMIC Fri Apr 7 10:32:52 MDT 2023 aarch64 GNU/Linux
Steps to reproduce:
~ # vcgencmd
Can't open device file: /dev/vcio
Try creating a device file with: sudo mknod /dev/vcio c 100 0
Maybe someone here can help me to figure this out. Thank you!
cc: @graysky2
I suspect your issue is that you're running the vanilla linux kernel (linux-aarch64) and not the RPi Foundation based kernel (linux-rpi).
Your suspect is right.
Before it was all working well with the vanilla kernel thanks probably to raspberrypi-firmware package, that has been deprecated 3 days ago in favor of raspberrypi-utils from this repo.
Switching for linux-rpi kernel fixed this issue.
Honestly don't know about vanilla kernel. If you want cool stuff on the RPi platform like hw decoding, use linux-rpi.
Hello,
Looks like I am having a very similar issue.
I am trying to get a set of python scripts (pipresents) running on a RPi 4B.
I do not know Python but the code seems to execute vcgencmd and throws an error. When I run vcgencmd as non-root, it throws OP's error. (Tried this on Arch ARM aarch64 as well as armv7h; both running linux-rpi; however it does work on RPi OS but I don't want to use a Debian-based system.)
It looks like there is a permission problem as it does what it has to as root:
[szg@alarm ~]$ uname -a
Linux alarm 6.1.61-2-rpi-ARCH #1 SMP PREEMPT Mon Nov 6 08:36:16 MST 2023 aarch64 GNU/Linux
[szg@alarm ~]$ vcgencmd get_mem gpu
Can't open device file: /dev/vcio
Try creating a device file with: sudo mknod /dev/vcio c 100 0
[szg@alarm ~]$ sudo vcgencmd get_mem gpu
gpu=76M
Exactly the same on armv7h.
Not sure whether this is expected behaviour since vcgencmd does work under normal user on RPi OS Bullseye:
szg@raspberrypi:~ $ uname -a
Linux raspberrypi 6.1.21-v8+ #1642 SMP PREEMPT Mon Apr 3 17:24:16 BST 2023 aarch64 GNU/Linux
szg@raspberrypi:~ $ vcgencmd get_mem gpu
gpu=76M
A quick update: booted back into Arch armv7 and added the szg user to the video group there. This does not help, even though permissions for /dev/vcio are identical in both OSes:
crw-rw---- 1 root video 10, 125 Nov 6 18:27 /dev/vcio
@pathcheatsheet In my case it was enough to add my user to the video group, disconnect and reconnect from ssh. I was able to run this after reconnecting:
alarm ~ $ vcgencmd get_mem gpu
gpu=256M
loki ~ $ id
uid=1000(alarm) gid=984(users) groups=984(users),985(video),998(wheel)