On Mon, Sep 28, 2020 at 02:31:55PM -0700, Jakub Kicinski wrote:

On Sat, 26 Sep 2020 23:06:26 +0200 Andrew Lunn wrote:

quoted

Not all ports of a switch need to be used, particularly in embedded
systems. Add a port flavour for ports which physically exist in the
switch, but are not connected to the front panel etc, and so are
unused.

This is missing the explanation of why reporting such ports makes sense.

Because this is a core devlink patch, we're talking really generalistic
here. And since devlink regions are a debugging features, it makes sense
to tell a debugging story. Let's say there is a switch which had
configured all its ports to be part of the flooding replication lists,
but also configured other things incorrectly such that attempting to
flood a frame to a disabled port would leak a memory buffer. After
enough time, the system would lock up. So unused ports are not absent
from the system and they might even make a difference if the procedure
to disable a port is buggy (and there would be no debugging without
bugs, right?). I see no reason why we would hide them. Devlink ports are
not net devices, I thought that was the whole point, to have insight
into the hardware and not have to deal with an approximate abstraction.