On Thu, 6 Jul 2017 21:53:46 +0000, Casey Leedom wrote: > | From: Jakub Kicinski <kubak...@wp.pl> > | Sent: Thursday, July 6, 2017 12:02 PM > | > | IMHO if something gets replugged all the settings should be reset. > | I feel that it's not entirely unlike replugging a USB adapter. Perhaps > | we should introduce some (devlink) notifications for SFP module events > | so userspace can apply whatever static user config it has? > > Absolutely a valid approach. As are all of the ones I outlined. > > But, and far more importantly, ideally _*ANY*_ such decision is made at an > architectural level to apply to all Link Parameters and Vendor Products. > The last thing a user wants to deal with is a hodge-podge of different > policies for different adapters from different vendors.
Agreed. Once we decided we should make the expected behaviour very clear the everyone. Sorry if I'm misunderstanding - are you suggesting we should keep the speed settings if hand-selected? My feeling is those should be reset if they are incompatible with the module. > As I noted in my previous letter: this is something new that we've never > faced before with any prior networking technology. All previous networking > technologies had a static set of Physical Port Capabilities fixed from the > moment a Host Diver/Firmware first see a Port. We're now facing a situation > where these can change dynamically from moment to moment based on what > Transceiver Module is inserted. > > With regard to this "architectural" issue, one way of trying to tease out > what model will be the simplest for users to work with is to ask: how do > users conceive of a "Port"? I.e. when a user requests that a particular > Link Parameter be applied to a Port, are they thinking that it only applies > to the current instantaneous combination of Adapter Transceiver Module Cage > + Transceiver Module? Or do they conceptualize a "Port" as being a higher > level entity? Hm. I'm beginning to come around on this. If my understanding of PHY sub-layers is correct the FEC layer shouldn't be reset on module unplug. OTOH when someone replaces a DAC with an optical module, keeping FEC around is not going to do any good to users...
