On Tue, Oct 27, 2009 at 21:55, Matt Domsch [off-list ref] wrote:

On Thu, Oct 22, 2009 at 12:36:20AM -0600, dann frazier wrote:

quoted

Here's a proof of concept to further the discussion..

The default filename uses the format:
  /dev/netdev/by-ifindex/$ifindex

This provides the infrastructure to permit udev rules to create aliases for
network devices using symlinks, for example:

  /dev/netdev/by-name/eth0 -> ../by-ifindex/1
  /dev/netdev/by-biosname/LOM0 -> ../by-ifindex/3

A library (such as the proposed libnetdevname) could use this information
to provide an alias->realname mapping for network utilities.

yes, this could work, as IFINDEX is already exported in the uevents,
and that's the primary value udev needs to set up the mapping.

While I like the little ifindex2name script you've got, I think udev
could simply call if_indextoname() to get this, and not call an
external program?  I suppose it could be a really really simple
external program too.

What's the point of all this? Why would udev ever need to find the
name of a device by the ifindex? The device name is the primary value
for the kernel events udev acts on.

I'd be fine with this approach.  It has the advantages of not
requiring a kernel change at all, and not creating a whole character
device which would be useless.  And it doesn't preclude someone in the
future from creating a char device for network devices should they so
choose.

Kay, what say you as udev owner?

That all sounds very much like something which will hit us back some
day. I'm not sure, if udev should publish such dead text files in
/dev, it does not seem to fit the usual APIs/assumptions where /sys
and /dev match, and libudev provides access to both. It all sounds
more like a database for a possible netdevname library, which does not
need to be public in /dev, right?

Thanks,
Kay
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