aipark wrote > Package: release-notes > Severity: minor > X-Debbugs-Cc: aip...@outlook.com > > 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.)
I'm not clear on what it was about your system that triggered this - for a start, was it a KVM virtual machine? If I can get some more details the first thing we'll want to update is the wiki page. > systemd v257 release notes and man subpage net-naming-scheme show new (That man page didn't reach Debian stable until the next release after the one the wiki page was written for, so there's only a link in "External References" to the version at freedesktop.org. I'll add one to https://manpages.debian.org/systemd/systemd.net-naming-scheme.7.html as well.) > "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. > The Debian NetworkInterfaceNames wiki page was helpful to debug this. > The listed udevadm command shows that naming scheme v257 has new > ID_NET_NAME_SLOT=ens18 entry. > > I guess by the usual schedule there are several months to go until > trixie becomes the stable release, and the above could change again. > That said I might suggest a short release notes entry in Debian. > systemd's own comment on this seemed easy to miss. So, the good news is that it *is* mentioned in a NEWS.gz file. The bad news is, apt-listchanges won't display that - and even if it did, the item is phrased as an obscure announcement about "The firmware_node/sun sysfs attribute" 278 lines down in the list of changes, giving no real hint about what sort of old name should be expected to change to what sort of new name under what sort of circumstances. If we're going to have to mention this in the release notes every single time, we probably ought to stop thinking of it as an item to go under "Possible issues during upgrade" and start advertising it under "Preparing for the upgrade" as a chronic bug that sysadmins always need to beware of any time they upgrade systemd. The only safe approach is to set up an /etc/systemd/network/*.link file to replace the "predictable names" with predictable names. Mind you, given that there's a mechanism for checking what your network interfaces will be called after the next reboot, why doesn't systemd run that in postinst and emit big warnings if they've changed? Or until then, that idea might at least form the basis for an alternative safety net to go on the wiki page. -- JBR with qualifications in linguistics, experience as a Debian sysadmin, and probably no clue about this particular package
