[systemd-devel] Better network naming on Hyper-V/Azure?

[Stephen Hemminger]

About a year ago there was some discussion on having persistent network names
on Hyper-V/Azure. Haiyang did some patches to add an attribute which
could be used by udev to do this. But there are some reluctance because
of how the channel id works.

The motivation to provide network naming is to allow vmbus to change to parallel probing.
Right now probing is serialized so naming is always in same order.

My question is what exactly does systemd/udev need to provide persistent
naming. The obvious ones are:
  1. Must be unique (although PCI slot isn't)
  2. Must be persistent across reboot.
  3. Must be stable if device is removed.

There are more questions.
  1. Is there a particular ordering and non-reuse requirement.
     Obviously, names have to be 15 characters or less but what else.
  2. How to handle the device associated with Accelerated Networking?
     Do you want to hide or rename the VF that is associated with the
     virtual device?

There are a couple of other quirks:
  1. The current cloudinit and other startup applications require eth0 as
     the administrative and always there interface, hard wired into the
     code. How to handle that?
  2. Hyper-V has the ability for host administrator to assign a name, but
     it is more of a free form string so it is used as default network description.
  3. Azure has names as part of the CLI for manipulating VM's but these
     are not currently exposed to guest. If this could happen would it help or
     hurt.