Bug#1110184: Fwd: Bug#1110184: release-notes: document /etc/sysctl.conf being dropped

[Samuel Plavec <samuelplavec@gmail.com>]

Thanks for the explanation.

On Tue, Aug 5, 2025 at 7:37 PM Justin B Rye <justin.byam.rye@gmail.com> wrote:
> My understanding was that the reason /etc/sysctl.conf was a symlink is
> that systemd doesn't read that file, so it has been deprecated for a
> while; [...]

I didn't know about the deprecation. The sysctl.conf manpage says that
"procps sysctl" is distinct from systemd-sysctl. It does *not* note the
deprecation, but notes that:
> Finally, procps sysctl reads /etc/sysctl.conf. This file is not used by
> systemd-sysctl, which means that some kernel parameters are not
> set depending on the implementation of sysctl that is installed.

The first sentence appears to be misleading (/etc/sysctl.conf is no
longer listed as a conffile, and is removed by dpkg on upgrade); see:
- https://salsa.debian.org/debian/procps/-/commit/77f54cb9d9951b193d2aaeb694e56061309eb3ef
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1076352
  - https://salsa.debian.org/debian/procps/-/commit/ac03e56e0eab2b4b0d2afa18250c1cf77b14c8de
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1085130
  - https://salsa.debian.org/debian/procps/-/commit/2f894fe720c2dda8cfc68c0f2873756235f63e9e

However, the manpage has actually recently been updated:
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1077187
- https://gitlab.com/procps-ng/procps/-/commit/ec590d5145668ea1868e1787c272d329ce5feba1

The bookworm manpage about procps sysctl.conf
(https://manpages.debian.org/bookworm/procps/sysctl.conf.5.en.html)
also doesn't mention the deprecation (or that /etc/sysctl.conf is
specific to procps) at all. Only a systemd changelog entry from 2014
says that:
> Create[d] a compat symlink /etc/sysctl.d/99-sysctl.conf as systemd-sysctl no
> longer reads /etc/sysctl.conf.

To sum up, bookworm changelogs and manpages do not mention
the deprecation, and 2014 changelogs only mention that under
systemd-sysctl, /etc/sysctl.conf works because of a "compat symlink".
Even under trixie, the sysctl.conf manpage is misleading. One has to
read the changelogs to learn that /etc/sysctl.conf was *already*
automatically removed and is no longer a valid conffile.

Therefore, I think that:
- the manpage sysctl.conf(5) from procps should mention that
  /etc/sysctl.conf shouldn't be used anymore;
- the release notes should prominently mention that /etc/sysctl.conf
  shouldn't be used anymore, and that it will be automatically
  removed on upgrade.

Regards,
Samuel Plavec