Cannot remove vsnd module #1

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1. jserv commented on Feb 15, 2024

   

   jserv

   on Feb 15, 2024

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   @Cuda-Chen, Can you confirm that vsnd_unregister_all() properly iterates the registered sound devices?
2. Cuda-Chen commented on Feb 16, 2024

   

   Cuda-Chen

   on Feb 16, 2024

   Last edited by Cuda-Chen

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   Hi @jserv ,

   After upgrading my system to 5.15.0-94-generic, it gets worse: the kernel cannot load vsnd module, and I think there are some issues of the recently Ubuntu distro. I will solve the cannot load module issue first.

   FYI, here are the outputs after loading the vsnd module:

   $ make check
   make check
   make -C /lib/modules/5.15.0-94-generic/build M=/home/jio/c_code/vsnd modules
   make[1]: Entering directory '/usr/src/linux-headers-5.15.0-94-generic'
   make[1]: Leaving directory '/usr/src/linux-headers-5.15.0-94-generic'
   scripts/verify.sh
   + sudo modprobe snd_pcm
   + sudo rmmod vsnd
   rmmod: ERROR: Module vsnd is not currently loaded
   + rm -f /tmp/audio.pcm
   + mkfifo /tmp/audio.pcm
   + sudo insmod vsnd.ko out_fifo_name=/tmp/audio.pcm
   insmod: ERROR: could not insert module vsnd.ko: Invalid module format
   + sleep 1
   + tee out.pcm
   + aplay CantinaBand3.wav
   Playing WAVE 'CantinaBand3.wav' : Signed 16 bit Little Endian, Rate 22050 Hz, Mono
   + sudo rmmod vsnd
   rmmod: ERROR: Module vsnd is not currently loaded
   + ffmpeg -f s16le -ar 22.05k -ac 1 -loglevel 8 -i out.pcm out.wav
   File 'out.wav' already exists. Overwrite? [y/N] 
   Not overwriting - exiting
   make: *** [Makefile:12: check] Error 1

   What's more, here are the results in dmesg while loading vsnd module:

   [26902.839728] module: x86/modules: Skipping invalid relocation target, existing value is nonzero for type 1, loc 0000000062f68630, val ffffffffc13faa3a
   
3. Cuda-Chen commented on Feb 17, 2024

   

   Cuda-Chen

   on Feb 17, 2024

   Last edited by Cuda-Chen

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   Hi @jserv ,

   After purging and reinstalling the linux-headers, it compiles without any errors (as I have not clean the linux-headers on my computer for years).

   For Ubuntu, to let vsnd play sound, you have to select the vsnd from System Settings -> Sounds (the system describe vsnd as Analog Output - Built-in Audio) or the test sound will be played by other sound devices.
   What's more, there is some interesting finding when using lsmod | grep vsnd:

   $ lsmod | grep vsnd
   vsnd                   16384  1
   snd_pcm               143360  7 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec,vsnd,snd_hda_core
   snd                   106496  24 snd_hda_codec_generic,snd_seq,snd_seq_device,snd_hda_codec_hdmi,snd_hwdep,snd_hda_intel,snd_hda_codec,snd_hda_codec_realtek,snd_timer,vsnd,snd_pcm,snd_rawmidi
   

   You can see that vsnd is occupied by some unknown kernel modules. I think I should realize how Ubuntu manage the sound device first (maybe the System Setting occupies vsnd so we can't rmmod vsnd?).
4. Cuda-Chen commented on Mar 18, 2024

   

   Cuda-Chen

   on Mar 18, 2024

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   Hi @jserv ,

   I would like to make some updates about my findings.

   I found vsnd cannot be removed once it plays any sound.
   To remove vsnd, I have to type pactl set-card-profile alsa_card.platform-vsnd.0 off and the vsnd will be able to be removed.

   What's more, it seems that the dmesg produces lagged output as follows (use this fork to re-produce):

   [ 3458.302210] start to unregister vsnd driver
   [ 3467.285842] Succeeded to load vsnd
   [ 3471.103242] START: channels 1 rate 22050
   [ 3502.116129] STOP
   [ 3557.413503] start to unregister vsnd components
   [ 3557.414614] end to unregister vsnd components
   

   Also, I think to designate the sound-playing device when testing should be more convenient so that we don't need to switch the sound output device from system setting manually.
5. Cuda-Chen commented on May 6, 2024

   

   Cuda-Chen

   on May 6, 2024

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   Close this as we mention that the contributors should temporarily disable downstream sound services such as PluseAudio and PipeWire in README.
6. Cuda-Chen

   closed this as completedon May 6, 2024