From: Jiri Pirko <jiri@resnulli.us>
To: Andrew Lunn <andrew@lunn.ch>
Cc: David Ahern <dsahern@gmail.com>, Jakub Kicinski <kuba@kernel.org>,
netdev@vger.kernel.org, davem@davemloft.net,
jacob.e.keller@intel.com, roopa@nvidia.com, mlxsw@nvidia.com,
vadimp@nvidia.com
Subject: Re: [patch net-next RFC 00/10] introduce line card support for modular switch
Date: Fri, 29 Jan 2021 08:20:15 +0100 [thread overview]
Message-ID: <20210129072015.GA4652@nanopsycho.orion> (raw)
In-Reply-To: <YBLHaagSmqqUVap+@lunn.ch>
Thu, Jan 28, 2021 at 03:17:13PM CET, andrew@lunn.ch wrote:
>On Thu, Jan 28, 2021 at 09:14:34AM +0100, Jiri Pirko wrote:
>> Wed, Jan 27, 2021 at 03:14:34PM CET, andrew@lunn.ch wrote:
>> >> >There are Linux standard APIs for controlling the power to devices,
>> >> >the regulator API. So i assume mlxreg-pm will make use of that. There
>> >> >are also standard APIs for thermal management, which again, mlxreg-pm
>> >> >should be using. The regulator API allows you to find regulators by
>> >> >name. So just define a sensible naming convention, and the switch
>> >> >driver can lookup the regulator, and turn it on/off as needed.
>> >>
>> >>
>> >> I don't think it would apply. The thing is, i2c driver has a channel to
>> >> the linecard eeprom, from where it can read info about the linecard. The
>> >> i2c driver also knows when the linecard is plugged in, unlike mlxsw.
>> >> It acts as a standalone driver. Mlxsw has no way to directly find if the
>> >> card was plugged in (unpowered) and which type it is.
>> >>
>> >> Not sure how to "embed" it. I don't think any existing API could help.
>> >> Basicall mlxsw would have to register a callback to the i2c driver
>> >> called every time card is inserted to do auto-provision.
>> >> Now consider a case when there are multiple instances of the ASIC on the
>> >> system. How to assemble a relationship between mlxsw instance and i2c
>> >> driver instance?
>> >
>> >You have that knowledge already, otherwise you cannot solve this
>>
>> No I don't have it. I'm not sure why do you say so. The mlxsw and i2c
>> driver act independently.
>
>Ah, so you just export some information in /sys from the i2c driver?
>And you expect the poor user to look at the values, and copy paste
>them to the correct mlxsw instance? 50/50 guess if you have two
>switches, and hope they don't make a typO?
Which values are you talking about here exactly?
>
>> >I still don't actually get this use case. Why would i want to manually
>> >provision?
>>
>> Because user might want to see the system with all netdevices, configure
>> them, change the linecard if they got broken and all config, like
>> bridge, tc, etc will stay on the netdevices. Again, this is the same we
>> do for split port. This is important requirement, user don't want to see
>> netdevices come and go when he is plugging/unplugging cables. Linecards
>> are the same in this matter. Basically is is a "splitter module",
>> replacing the "splitter cable"
>
>So, what is the real use case here? Why might the user want to do
>this?
>
>Is it: The magic smoke has escaped. The user takes a spare switch, and
>wants to put it on her desk to configure it where she has a comfy chair
>and piece and quiet, unlike in the data centre, which is very noise,
>only has hard plastic chair, no coffee allowed. She makes her best
>guess at the configuration, up/downs the interfaces, reboots, to make
>sure it is permanent, and only then moves to the data centre to swap
>the dead router for the new one, and fix up whatever configuration
>errors there are, while sat on the hard chair?
>
>So this feature is about comfy chair vs hard chair?
I don't really get the question, but configuring switch w/o any linecard
and plug the linecards in later on is definitelly a usecase.
>
>I'm also wondering about the splitter port use case. At what point do
>you tell the user that it is physically impossible to split the port
>because the SFP simply does not support it? You say the netdevs don't
>come/go. I assume the link never goes up, but how does the user know
>the configuration is FUBAR, not the SFP? To me, it seems a lot more
>intuitive that when i remove an SFP which has been split into 4, and
>pop in an SFP which only supports a single stream, the 3 extra netdevs
>would just vanish.
As I wrote easlier in this thread, for hw that supports it, there should
be possibility to turn on "autosplit" mode that would do exactly what
you describe. But depends on a usecase. User should be in power to
configure "autosplit" for split cables and "autodetect" for linecards.
Both should be treated in the same way I believe.
>
> Andrew
>
next prev parent reply other threads:[~2021-01-29 7:21 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 [this message]
[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
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210129072015.GA4652@nanopsycho.orion \
--to=jiri@resnulli.us \
--cc=andrew@lunn.ch \
--cc=davem@davemloft.net \
--cc=dsahern@gmail.com \
--cc=jacob.e.keller@intel.com \
--cc=kuba@kernel.org \
--cc=mlxsw@nvidia.com \
--cc=netdev@vger.kernel.org \
--cc=roopa@nvidia.com \
--cc=vadimp@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).