Re: [RFC PATCH net-next 0/3] ethtool: Add link down reason reporting

[Jakub Kicinski <kubakici@wp.pl>]

On Thu, 22 Jun 2017 14:37:26 +0300, Gal Pressman wrote:
> > Any particular reason for implementing this ABI in ethtool rather than
> > via some netlink-based interface?  Devlink naturally comes to mind,
> > given that cabling problems are not really related to the L2 and netdev
> > shouldn't be required for diagnostics..  
> 
> ethtool is already used for reporting and handling of link related stuff through get/set_link_ksettings.
> How is reporting the link modes/port type/speed/etc different from this?
> This feature is only an extension of the already existent "link detected" field.
> 
> Implementing this ABI in devlink is a good idea, but it shouldn't be instead of ethtool but in addition to ethtool.
> Many users already use ethtool for this kind of info, we can tell them to use devlink to check why their link is down,
> but I think it's nicer to have it all in one place.

I understand where you're coming from, but it's a matter of user space
tooling.  If ethtool has to invoke devlink or know a little of netlink
to get this info, so be it.  Ethtool implements a lot of features, I'm
worried that if we select where things are added based on where the
similar features already live, we will be stuck adding ioctls for
ever :(

But I'm happy to let this go if others don't feel the same way ;)  

In general thanks for working on this feature, it's very useful!