The Linux Kernel Dropping Its Unused Built-In Software Echo Cancellation Code
Queued up for removal in the upcoming Linux 6.16 kernel cycle is dropping "echo", a software-based echo cancellation code within the kernel intended for telecommunications use. But it's old, unmaintained, and likely not actively used.
Queued up within the char-misc-next code for the "char/misc" updates intended for Linux 6.16 is dropping this echo module.
Dr. David Alan Gilbert argued in the patch dropping the 1k+ lines of code for this software-based echo canncellation code:
So the echo canceller code is itself set to be cancelled with the upcoming Linux 6.16 merge window. This code is behind the "ECHO" Kconfig build switch for the Linux kernel.
Queued up within the char-misc-next code for the "char/misc" updates intended for Linux 6.16 is dropping this echo module.
Dr. David Alan Gilbert argued in the patch dropping the 1k+ lines of code for this software-based echo canncellation code:
"'echo' is a software echo canceller for telco use, however it's not used in the kernel at all.
Remove it.
It was moved from staging in 2014 by commit Fixes: 6e2055a9e56e ("staging: echo: move to drivers/misc/")
Some discussion on lkml:
https://lore.kernel.org/all/Z7tZhYET41DAoHVf@gallifrey/
with Arnd and Harald, led to the 'dahdi' package which is part of Asterisk:
https://gitea.osmocom.org/retronetworking/dahdi-linux
which can build with the 'echo' module, but is normally configured with out it. Dahdi is large, old, only lightly maintained and with a big API, so there's no hope now of ever merging it into the main kernel tree.
Debian do package Dahdi, and in their package they actually include a copy of the 'echo' module rather than using the kernel from the upstream kernel. So even in the few cases where it is packaged and built, the kernel copy isn't used."
So the echo canceller code is itself set to be cancelled with the upcoming Linux 6.16 merge window. This code is behind the "ECHO" Kconfig build switch for the Linux kernel.