Dear Eduardo,

On 2020-03-01 06:46, Eduardo Ochs wrote:

> I have two Debian 10 partitions on my laptop - a venerable ThinkPad
> T400 with libreboot - and in one of these partitions (in /dev/sda5,
> a.k.a. the "bad partition") sound doesn't work, and in the other one
> (/dev/sda4, a.k.a. the "good partition" from here on) it does...
> The "bad partition" had Debian 9, and after I upgraded it to 10 with
> "apt-get dist-upgrade" sound stopped working on it (details soon). I
> then installed Debian 10 from a installation pen drive on an empty
> partition to be able to test things on both; sound works on it
> perfectly, so let's call it the "good partition".
> I've tried several sound debugging recipes that I found on the
> internets and they didn't work, so I've decided to use this as an
> excuse to learn more about sound on Linux.
> "Sound doesn't work" here means that all applications that play
> sound - including speaker-test, that seems to be very low-level -
> behave normally, but I can't hear anything - even when I use alsamixer
> to set "Master", "Headphone", "Speaker", "PCM", "Beep" and "Internal"
> all to the maximum level.


> About pavucontrol: in the bad partition the only output device that
> appears in the "Output Devices" tab is called "Dummy Output". This
> looks like a red flag, but I got the impression - please confirm -
> that PulseAudio runs on a level above ALSA, and problems with
> PulseAudio should not affect the behavior of speaker-test.
> So: any hints? What should I add to my script to compare the behavior
> of ALSA in the two partitions? Am I wrong in thinking that
> speaker-test ignores PulseAudio? How do I examine the status of
> PulseAudio without using the GUI? Are there ways to mute and unmute
> the sound using the functions in /usr/share/alsa/ What
> else?...

Please attach the output of `` [1] for the non-working and
working case.

Kind regards,



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