[systemd-devel] network interface renaming via PCI ID w/ systemd-udevd

Matthew Hall mhall at mhcomputing.net
Wed Nov 11 23:29:59 PST 2015

On Thu, Nov 12, 2015 at 07:59:03AM +0200, Mantas Mikul??nas wrote:
> I'm not sure if udev even still _allows_ renaming to eth*, but even if it
> does, that's explicitly not supported. (For example, between the time eth0
> appears and the "rename to eth1" rule gets processed, another eth1 might
> also appear, and the rename would fail.) If you want custom names, use en*
> or port* or lan* or some other prefix.

Let me try and put this another way. I have been using UNIX 24 years. I have 
typed the characters eth0 so long that it's long since been hardcoded into my 
fingers; trying to change it would drive me crazy and serve no beneficial 
purpose besides confusing me when I am trying to get work done. The computer 
is a tool to help me solve problems. It makes more sense to get the computer 
to accomodate the users than the other way around.

Dynamically populating the "eth*" namespace with random unexpected network 
interfaces on the fly should honestly be considered a bug not a feature. If 
they are dynamically populated then they can be placed anywhere, so why not 
place them under net0, net1, net2, etc.?

It makes no sense to put them into the middle of a namespace that has decades 
of what had previously been pretty clear easy-to-follow traditions behind it.

It took several hours even to find wrong examples how to rename an interface 
using a PCI ID because the page didn't bother to explain the options it listed 
with any kind of examples. No new users are going to have much hope of making 
sense of any of the behavior of this. Of course, provided they even manage to 
follow the cryptic instructions to registed to update the wiki page if they do 
figure it out.

> they directly compare the values you'd see in `udevadm monitor --env` or 
> `udevadm info /sys/class/net/eth0`.

Thanks for these. It should help a lot in the future.


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