Bug#1092176: release-notes: systemd v257 has new rules for network interface names

Michael Biebl <[email protected]> Tue, 29 Jul 2025 20:48:14 +0200

Newsgroups	gmane.linux.debian.devel.documentation
Message-ID	<8a7fe5bc-0b1b-494d-aa8e-1ee5a888a2c7__42372.1575805516$1753815978$gmane$org@debian.org>

On Sun, 05 Jan 2025 11:50:31 -0600 aipark <[email protected]> wrote:
> Package: release-notes
> Severity: minor
> X-Debbugs-Cc: [email protected]
> 
> I updated a staging bookworm VM with VirtIO NIC to trixie and
> temporarily lost network access because enp6s18 became ens18,
> and subsequently /etc/network/interfaces 'allow-hotplug enp6s18'
> no longer functioned. (Weirdly, 'auto' still works.)
> 
> systemd v257 release notes and man subpage net-naming-scheme show new
> "PCI slot number is now read from firmware_node/sun sysfs file"
> and documented 'net.naming_scheme=v255' kernel cmdline reverted the
> changes back to what it was in bookworm with systemd v252.

So, for a remote system where you don't want the naming scheme to 
change, would it make sense to add a recommendation to pin it to the 
systemd version the system was originally installed with?

Say for a bookworm system, you add "net.naming_scheme=v252" to the 
kernel command line.
Then you can dist-upgrade and boot into your new trixie system 
(including the new kernel).

And at a later point, you can decide to bump net.naming_scheme to v257 
at a more opportune time.

Michael

[1] 
https://www.freedesktop.org/software/systemd/man/latest/systemd.net-naming-scheme.html

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