Re: is the systemd .link mechanism supposed to work?
On Sun, Jul 28, 2019 at 11:04:41AM +0200, Luca Olivetti wrote:
> El 27/7/19 a les 23:20, Reco ha escrit:
>
> >
> > > yet it always gets the name wlxe894f615307a.
> >
> > What you're doing colud work.
> > The problem is - you have NIC that's attached via USB, so the usual
> > rules do not apply.
> >
> > The reason of it - /lib/udev/rules.d/73-usb-net-by-mac.rules, that's
> > applied after your .link file rename an interface.
>
> Is this madness due to systemd or debian packaging? In either case I think it should be mentioned in the release notes.
One of the things that help me keep sanity with these thing is a systemd
source tree. So,
$ git remote -v
origin https://github.com/systemd/systemd (fetch)
origin https://github.com/systemd/systemd (push)
$ git log -- rules/73-usb-net-by-mac.rules | wc -l
0
Seems to be a Debian addition, due to:
systemd (234-1) unstable; urgency=medium
...
[ Martin Pitt ]
* udev README.Debian: Update transitional rules and mention *.link
* files.
- 01-mac-for-usb.link got replaced with 73-usb-net-by-mac.rules
Although I'm pretty sure I bumped into this in stretch.
Would be a nice joke if this configuration file crept upstream though ;)
> > > OTOH the wired interface is always named eth0 (even with no .link file), even if it should be
> > >
> > > # udevadm test-builtin net_id /sys/class/net/eth0 2>/dev/null
> > > ID_NET_NAME_MAC=enx00160141ad18
> > > ID_OUI_FROM_DATABASE=BUFFALO.INC
> >
> > Systemd (udev is a part of it) is x86 centric. Unless NIC is connected
> > to PCI or USB - it does not know how to rename them Predictably™.
> >
> > In your place I'd consider myself lucky - at least you have a network
> > interface that's always called eth0, the way the kernel wants it.
>
> I am lucky until systemd behaviour changes: do I have the absolute certainty that, upon upgrading to buster, it will still be named eth0?
Yes. No. Maybe. These things are called Predictable because they aren't.
A modern systemd paradox, if you will.
For instance, then they added (Un)Predictable Naming to virtio devices
in stretch - that was rough.
Migrating to buster I was "pleasantly" surprised to see udev renaming
interfaces that I created with "ip link add" (apparently because a
meatbag named it too closely to the Dreaded Kernel Name).
The solution was simple each time, but consisted of two steps.
1) Blacklilst that 73*rules file. Does more harm than good anyway.
2) Create an appropriate network link file(s), with several matching
attributes. No, MAC alone won't suffice. And ID_PATH can change between
stretch and buster, but that's upstream who gets the credit for *that*.
> > > Extra points if it involves getting rid of systemd altogether ;-)
> >
> > It won't help you here. To solve this particular problem once and for
> > all, you need a replacement for udev, which Debian does not provide.
>
> Thank you, that was tongue in cheek (though the more I use systemd the more I hate it).
You're welcome.
Reco
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