[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Bug#881771: Unclear which interface name will be used



On Tue, 23 Apr 2019 21:05:05 +0100
Justin B Rye <justin.byam.rye@gmail.com> wrote:

> Greg Wooledge wrote:
> > In the release notes, there's a udevadm command which is supposed to
> > tell us what the new interface name will be, but I had some trouble
> > interpreting the output.
> > 
> > wooledg:~$ udevadm test-builtin net_id /sys/class/net/eno1
> > 2>/dev/null ID_NET_NAMING_SCHEME=v240
> > ID_NET_NAME_MAC=enxa08cfdc389e0
> > ID_OUI_FROM_DATABASE=Hewlett Packard
> > ID_NET_NAME_ONBOARD=eno1
> > ID_NET_LABEL_ONBOARD=enOnboard Lan
> > ID_NET_NAME_PATH=enp0s31f6  

> > I thought the new interface name would be enp0s31f6 but it turned
> > out to be eno1 instead.

>The complication
> you've run into there is the fact that ID_NET_NAME_ONBOARD names,
> where present, take priority over ID_NET_NAME_PATH names (and your
> ID_NET_NAME_PATH name is itself a complicated one).  It's hard to
> summarise completely and concisely (there are further problems with
> USB dongles and virtual machines and so on), so what we most need is
> good external sources we can point to.  The upstream docs at
> https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/
> *do* cover your case (the bit about "1. Names [...] for on-board
> devices"), but it doesn't exactly leap out at you.

> 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.

Regards,

Karl <kop@meme.com>
Free Software:  "You don't pay back, you pay forward."
                 -- Robert A. Heinlein


Reply to: