ALSA Sequencer fails. Missing /dev/snd/seq

Troubleshooting
1

It seems that DietPi is compiled without the ALSA sequencer. It is not available in the kernel or as a modprobe module. I really need the sequencer. What are my options?

Creating a bug report/issue

I have searched the existing open and closed issues

Required Information

  • cat /boot/dietpi/.version

G_DIETPI_VERSION_CORE=10

G_DIETPI_VERSION_SUB=5
G_DIETPI_VERSION_RC=2
G_GITBRANCH=‘master’
G_GITOWNER=‘MichaIng’

  • echo $G_DISTRO_NAME $G_RASPBIAN

trixie

  • uname --all

Linux robs-keyboard 6.18.37-current-sunxi64 #1 SMP PREEMPT Sat Jun 27 10:06:50 UTC 2026 aarch64 GNU/Linux

  • dpkg --print-architecture

arm64

  • echo $G_HW_MODEL_NAME or (EG: RPi3)

Orange Pi Zero 2W (aarch64)

Power supply is USB charger 2000mA
SD is Sandisk Ultra

Steps to reproduce

aplaymidi -l

Expected behaviour

Port Client name Port name
14:0 Midi Through Midi Through Port-0

Actual behaviour

ALSA lib seq_hw.c:540:(snd_seq_hw_open) open /dev/snd/seq failed: No such file or directory
Cannot open sequencer - No such file or directory

2

I found some similiar issues, maybe you can try their solutions.

Did you make a kernel update and forgot to reboot maybe?

Update: I resolved this. If anyone stumbles here, modprobe snd_seq. If your pi fails, maybe check that you rebooted the pi since recent kernel update. This was the case with me which I confirmed by checking runtime kernel version uname with where snd_req module was found in /lib/modules

If this is not helping your probably need to recompile your kernel with the wanted module

3

I guess its an issue with the incomplete audio support for this board, and the audio+Ethernet expansion board in particular you are probably using?

Audio support for the OPi Zero 2W is not part of mainline Linux, but patched inside along with Ethernet and stuff of the expansion board. It never fully worked, and more broke when things were ported from Linux 6.12 to 6.18.

Some part of the story can be found here: No sound card detected for Opi zero 2w

4

Hi all

For my first board OPI zero 2w with kernel 6.12, ethernet work on the expansion board

I found this

root@DietPi:~# uname -a
Linux DietPi 6.12.76-current-sunxi64 #1 SMP Thu Mar  5 15:04:32 UTC 2026 aarch64 GNU/Linux
root@DietPi:~# cd /dev/snd
root@DietPi:/dev/snd# ls
by-path  controlC0  pcmC0D0c  pcmC0D0p	seq  timer
root@DietPi:/dev/snd# aplaymidi -l
 Port    Client name                      Port name
root@DietPi:/dev/snd#

For the second with kernel 6.18, Connected via wifi

I found this

root@DietPi:~# uname -a
Linux DietPi 6.18.37-current-sunxi64 #1 SMP PREEMPT Sat Jun 27 10:06:50 UTC 2026 aarch64 GNU/Linux
root@DietPi:~# cd /dev/snd
root@DietPi:/dev/snd# ls
by-id  by-path	controlC0  pcmC0D0c  pcmC0D0p  timer
root@DietPi:/dev/snd# aplaymidi -l
ALSA lib seq_hw.c:540:(snd_seq_hw_open) open /dev/snd/seq failed: No such file or directory
Cannot open sequencer - No such file or directory
root@DietPi:/dev/snd#

No sequencer module

If you want to downgrade the kernel use this command

apt install linux-{image,dtb}-current-sunxi64=26.02.0-trunk-dietpi8