On 15-08-27 12:27 AM, Jiri Pirko wrote: > Thu, Aug 27, 2015 at 09:16:44AM CEST, sfel...@gmail.com wrote: >> From: Scott Feldman <sfel...@gmail.com> >> >> In the switchdev model, we use netdevs to represent switchdev ports, but we >> have no representation for the switch itself. So, introduce a new switchdev >> device class so we can define semantics and programming interfaces for the >> switch itself. Switchdev device class isn't tied to any particular bus. >> >> This patch set is just the skeleton to get us started. It adds the sysfs >> object registration for the new class and defines a class-level attr "foo". >> With the new class, we could hook PM functions, for example, to handle power >> transitions at the switch level. I registered rocker and get: >> >> $ ls /sys/class/switchdev/5254001235010000/ >> foo power subsystem uevent > > No, please avoid adding anything to sysfs. If we need to add anything, > lets make is accesible using Netlink only. > > >> >> So what next? I'd rather not build APIs around sysfs, so we need a netlink >> API >> we can build on top of this. It's not really rtnl. Maybe genl would work? >> What ever it is, we'd need to teach iproute2 about a new 'switch' command. >> >> Netlink API would allow us to represent switch-wide objects such as >> registers, >> tables, stats, firmware, and maybe even control. I think with with netlink >> TLVs, we can create a framework for these objects but still allow the switch >> driver provide switch-specific info. For example, a table object: >> >> [TABLES] >> [TABLE] >> [FIELDS] >> [FIELD] >> [ID, TYPE] >> [DATA] >> [ID, VALUE] > > Alert! I feel that someone would like to abuse this iface for writing > configuration through. This should be read-only by design. I also think > that this should not be something switch-specific. I believe that NIC > drivers would benefit from this iface as well when they want to expose > something. I think we should use genl for this. >
One place where read-only may not make sense is when the tables can be provisioned/configured. Many switches have the ability to be configured with "profiles". For a simple example some hardware use a single table that can be divided into an IPv4 and an IPv6 section. We don't have an interface to do this today. And I don't want to see this being "shipped" as magic firmware updates. So a well-defined netlink interface seems the best approach to me. Of course like any UAPI we should be a bit cautious adding new bits if we can't remove them. > >> >> Maybe iproute2 has pretty-printers for specific switches like ethtool has for >> reg dumps. > > I feel like a lot of what you described overlaps with existing > interfaces and tools. Why don't we just reuse that? For firmware for > example, just take one of the ports. Same for stats (I plan to expose my > mlxsw switch-wide stats in ethtool so they are accessible through every > port netdevice). > > I still do not see the need for new device class. I have strong feeling > that it should be avoided. > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
