From: Jakub Kicinski <kuba@kernel.org>
To: Jiri Pirko <jiri@resnulli.us>
Cc: netdev@vger.kernel.org, davem@davemloft.net,
jacob.e.keller@intel.com, roopa@nvidia.com, mlxsw@nvidia.com
Subject: Re: [patch net-next RFC 00/10] introduce line card support for modular switch
Date: Mon, 18 Jan 2021 09:59:28 -0800 [thread overview]
Message-ID: <20210118095928.001b5687@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> (raw)
In-Reply-To: <20210118130009.GU3565223@nanopsycho.orion>
On Mon, 18 Jan 2021 14:00:09 +0100 Jiri Pirko wrote:
> >> >Or to put it differently IMO the netdev should be provisioned if the
> >> >system has a port into which user can plug in a cable. When there is
> >>
> >> Not really. For slit cables, the ports are provisioned not matter which
> >> cable is connected, slitter 1->2/1->4 or 1->1 cable.
> >>
> >>
> >> >a line card-sized hole in the chassis, I'd be surprised to see ports.
> >> >
> >> >That said I never worked with real world routers so maybe that's what
> >> >they do. Maybe some with a Cisco router in the basement can tell us? :)
> >>
> >> The need for provision/pre-configure splitter/linecard is that the
> >> ports/netdevices do not disapper/reappear when you replace
> >> splitter/linecard. Consider a faulty linecard with one port burned. You
> >> just want to replace it with new one. And in that case, you really don't
> >> want kernel to remove netdevices and possibly mess up routing for
> >> example.
> >
> >Having a single burned port sounds like a relatively rare scenario.
>
> Hmm, rare in scale is common...
Sure but at a scale of million switches it doesn't matter if a couple
are re-configuring their routing.
> >Reconfiguring routing is not the end of the world.
>
> Well, yes, but you don't really want netdevices to come and go then you
> plug in/out cables/modules. That's why we have split implemented as we
> do. I don't understand why do you think linecards are different.
If I have an unused port it will still show up as a netdev.
If I have an unused phymod slot w/ a slot cover in it, why would there
be a netdev? Our definition of a physical port is something like "a
socket for a networking cable on the outside of the device". With your
code I can "provision" a phymod and there is no whole to plug in a
cable. If we follow the same logic, if I have a server with PCIe
hotplug, why can't I "provision" some netdevs for a NIC that I will
plug in later?
> Plus, I'm not really sure that our hw can report the type, will check.
I think that's key.
> One way or another, I think that both configuration flows have valid
> usecase. Some user may want pre-configuration, some user may want auto.
> Btw, it is possible to implement splitter cable in auto mode as well.
Auto as in iterate over possible configs until link up? That's nasty.
> >> >If the device really needs this configuration / can't detect things
> >> >automatically, then we gotta do something like what you have.
> >> >The only question is do we still want to call it a line card.
> >> >Sounds more like a front panel module. At Netronome we called
> >> >those phymods.
> >>
> >> Sure, the name is up to the discussion. We call it "linecard"
> >> internally. I don't care about the name.
> >
> >Yeah, let's call it something more appropriate to indicate its
> >breakout/retimer/gearbox nature, and we'll be good :)
>
> Well, it can contain much more. It can contain a smartnic/fpga/whatever
> for example. Not sure we can find something that fits to all cases.
> I was thinking about it in the past, I think that the linecard is quite
> appropriate. It connects with lines/lanes, and it does something,
> either phy/gearbox, or just interconnects the lanes using smartnic/fpga
> for example.
If it has a FPGA / NPU in it, it's definitely auto-discoverable.
I don't understand why you think that it's okay to "provision" NICs
which aren't there but only for this particular use case.
next prev parent reply other threads:[~2021-01-18 18:00 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-13 12:12 [patch net-next RFC 00/10] introduce line card support for modular switch Jiri Pirko
2021-01-13 12:12 ` [patch net-next RFC 01/10] devlink: add support to create line card and expose to user Jiri Pirko
2021-01-15 15:47 ` Ido Schimmel
2021-01-13 12:12 ` [patch net-next RFC 02/10] devlink: implement line card provisioning Jiri Pirko
2021-01-15 16:03 ` Ido Schimmel
2021-01-15 16:51 ` Jiri Pirko
2021-01-15 18:09 ` Ido Schimmel
2021-01-18 12:50 ` Jiri Pirko
2021-01-13 12:12 ` [patch net-next RFC 03/10] devlink: implement line card active state Jiri Pirko
2021-01-15 16:06 ` Ido Schimmel
2021-01-15 16:52 ` Jiri Pirko
2021-01-13 12:12 ` [patch net-next RFC 04/10] devlink: append split port number to the port name Jiri Pirko
2021-01-13 12:12 ` [patch net-next RFC 05/10] devlink: add port to line card relationship set Jiri Pirko
2021-01-15 16:10 ` Ido Schimmel
2021-01-15 16:53 ` Jiri Pirko
2021-01-13 12:12 ` [patch net-next RFC 06/10] netdevsim: introduce line card support Jiri Pirko
2021-01-13 12:12 ` [patch net-next RFC 07/10] netdevsim: allow port objects to be linked with line cards Jiri Pirko
2021-01-13 12:12 ` [patch net-next RFC 08/10] netdevsim: create devlink line card object and implement provisioning Jiri Pirko
2021-01-15 16:30 ` Ido Schimmel
2021-01-15 16:54 ` Jiri Pirko
2021-01-13 12:12 ` [patch net-next RFC 09/10] netdevsim: implement line card activation Jiri Pirko
2021-01-13 12:12 ` [patch net-next RFC 10/10] selftests: add netdevsim devlink lc test Jiri Pirko
2021-01-13 13:39 ` [patch iproute2/net-next RFC] devlink: add support for linecard show and provision Jiri Pirko
2021-01-14 2:07 ` [patch net-next RFC 00/10] introduce line card support for modular switch Andrew Lunn
2021-01-14 7:39 ` Jiri Pirko
2021-01-14 22:56 ` Jacob Keller
2021-01-15 14:19 ` Jiri Pirko
2021-01-19 11:56 ` Jiri Pirko
2021-01-19 14:51 ` Andrew Lunn
2021-01-20 8:36 ` Jiri Pirko
2021-01-20 13:56 ` Andrew Lunn
2021-01-20 23:41 ` Jakub Kicinski
2021-01-21 0:01 ` Andrew Lunn
2021-01-21 0:16 ` Jakub Kicinski
2021-01-21 15:34 ` Jiri Pirko
2021-01-21 15:32 ` Jiri Pirko
2021-01-21 16:38 ` David Ahern
2021-01-22 7:28 ` Jiri Pirko
2021-01-22 14:13 ` Andrew Lunn
2021-01-26 11:33 ` Jiri Pirko
2021-01-26 13:56 ` Andrew Lunn
2021-01-27 7:57 ` Jiri Pirko
2021-01-27 14:14 ` Andrew Lunn
2021-01-27 14:57 ` David Ahern
2021-01-28 8:14 ` Jiri Pirko
2021-01-28 14:17 ` Andrew Lunn
2021-01-29 7:20 ` Jiri Pirko
[not found] ` <YBQujIdnFtEhWqTF@lunn.ch>
2021-01-29 16:45 ` Vadim Pasternak
2021-01-29 17:31 ` Andrew Lunn
2021-01-30 14:19 ` Jiri Pirko
[not found] ` <251d1e12-1d61-0922-31f8-a8313f18f194@gmail.com>
2021-02-01 8:16 ` Jiri Pirko
2021-02-01 13:41 ` Andrew Lunn
2021-02-03 14:57 ` Jiri Pirko
2021-02-03 16:26 ` Andrew Lunn
2021-02-01 1:43 ` Andrew Lunn
2021-01-22 8:05 ` Jiri Pirko
2021-01-19 16:23 ` David Ahern
2021-01-20 8:37 ` Jiri Pirko
2021-01-14 2:27 ` Jakub Kicinski
2021-01-14 7:48 ` Jiri Pirko
2021-01-14 23:30 ` Jakub Kicinski
2021-01-15 14:39 ` Jiri Pirko
2021-01-15 19:26 ` Jakub Kicinski
2021-01-18 13:00 ` Jiri Pirko
2021-01-18 17:59 ` Jakub Kicinski [this message]
2021-01-19 11:51 ` Jiri Pirko
2021-01-18 22:55 ` David Ahern
2021-01-22 8:01 ` Jiri Pirko
2021-01-14 22:58 ` Jacob Keller
2021-01-14 23:20 ` Jakub Kicinski
2021-01-15 14:40 ` Jiri Pirko
2021-01-15 15:43 ` Ido Schimmel
2021-01-15 16:55 ` Jiri Pirko
2021-01-15 18:01 ` Ido Schimmel
2021-01-18 13:03 ` Jiri Pirko
2021-01-18 18:01 ` Edwin Peer
2021-01-18 22:57 ` David Ahern
2021-01-18 23:40 ` Edwin Peer
2021-01-19 2:39 ` David Ahern
2021-01-19 5:06 ` Edwin Peer
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