Bug#881771: Unclear which interface name will be used
Karl O. Pinc wrote:
>> https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/
[...]
>> Oh, looking at it again: maybe where it currently says
>>
>> <para>
>> This should give enough information to devise a migration plan.
>> (The <literal>udevadm</literal> output will include a fallback
>> MAC-based name, sometimes needed for USB network hardware.)
>> </para>
>>
>> We could fit in some sort of mention of ID_NET_NAME_ONBOARD as well?
>
> It would sure be nice to have an ordered list where the topmost
> in the list which appears in the udevadm output is used:
>
> ID_NET_NAME_ONBOARD
> ID_NET_NAME_PATH
> ID_NET_NAME_MAC
>
> And so forth. I don't even know if this makes sense but
> without some guidance there's just no way for
> the reader to know what name the kernel will use.
Yes, if you study the freedesktop.org page (which unhelpfully leaves
out the actual ID_NET_NAME_ terms) you'll see that by default it's
ONBOARD (eno1)
SLOT (ens1)
PATH (which may look like anything from enp0s1f1 to eth0)
MAC (enx101010101010)
*except* that there are several ways of overriding these defaults, and
one of them may have been set up without the user knowing about it
(this whole thing is after all being set off by the fact that they've
got a "legacy" .rules file). Then again Google also tells me horror
stories of firmware/kernel/udev interactions that unexpectedly
resurrect different name schemes. And this is just ethernet NICs!
I don't think it's realistic to expect that the Buster release-notes
could contain an accurate, user-friendly guide covering everything
that people need to know, even if they're running a laptop with a
phone dongle, a VM with an out-of-date kernel, or a server with
infiniband hardware where the previous sysadmin set up crazy .rules
files! We're going to have to leave corner cases to external
sources, and it isn't clear to me how common even things like ONBOARD
and SLOT names are.
After sleeping on it, here's an attempt to stuff more advice into the
above paragraph:
<para>
This should give enough information to devise a migration plan.
(If the <literal>udevadm</literal> output includes an
<quote>onboard</quote> name, that takes priority; MAC-based names
are normally treated as a fallback, but may be needed for USB
network hardware.)
</para>
--
JBR with qualifications in linguistics, experience as a Debian
sysadmin, and probably no clue about this particular package
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