On [0], you can read "In both cases the device naming is subject to the
usual guest or backend domain facilities for renaming network devices".
It says "naming/renaming", but you can assume "detecting".
I also checked which net_ids udev knows about and the only things that
pop up are:
ID_NET_NAMING_SCHEME=v247
ID_NET_NAME_MAC=enx00163efd832b
ID_OUI_FROM_DATABASE=Xensource, Inc.
Is it from dom0 or domU ?
Are you using "net.ifnames=0" on the domU kernel command line ?
"v247" looks like systemd "predictive naming scheme" (eth -> enX).
From bookworm on, domUs vifs get named enXN (enX0, enX1, ...).
Read on :
https://www.debian.org/releases/stable/i386/release-notes/ch-information.en.html#xen-network
This is from the domU, running bullseye with a bookworm dom0.
See how ethN interfaces get messed up, like in your setup, but
predictable names would work, as you can see in "altname enXN" :
eth1 (:01) -> enX1
eth2 (:10) -> enX10
eth3 (:02) -> enX2
I could not get our bullseye domU to show the "predictable names" even
though i tried installing the bullseye-backports kernel 6.1.
After you wrote this i installed udev 252.5 from backports and it now
uses the correct enXn interface names, even with kernel 5.10.
So, my answer does not tell you if something changed in Xen itself, only
in Debian.
But I guess it relates to what Xen devs told us : vifs detection order
cannot be relied upon, that's why "predictable names" were invented.
The vif detection part is related to the domains kernels, not Xen itself
(at least that's what I understood).
Using eth0 nowadays is a bit like using /dev/sda for hard drives, it's
considered legacy as it may create problems in some setups, like yours
(ie. for disks, it's recommended to use UUIDs or /dev/disk/by-*).
I hope this answers your question.
Thank you, yes it does.
In our case the dom0 was updated to bookworm while the domU is still
running bullseye.
-> updated Xen so the vif detection order changed (which we relied on)
-> the predictable network names for Xen don't work with bullseye
So my new resolution for bullseye domUs on a bookworm dom0 is to install
udev from backports and change the domUs network config to use the new
enXn naming scheme instead of ethn.
