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From: Arnd Bergmann <arnd@kernel.org>
To: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>,
	Networking <netdev@vger.kernel.org>,
	Jakub Kicinski <kuba@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Naresh Kamboju <naresh.kamboju@linaro.org>,
	Lars Povlsen <lars.povlsen@microchip.com>,
	Steen Hegelund <Steen.Hegelund@microchip.com>,
	Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Andrew Lunn <andrew@lunn.ch>,
	Vivien Didelot <vivien.didelot@gmail.com>,
	Ido Schimmel <idosch@nvidia.com>, Jiri Pirko <jiri@nvidia.com>,
	Roopa Prabhu <roopa@nvidia.com>,
	Nikolay Aleksandrov <nikolay@nvidia.com>,
	Linux Kernel Functional Testing <lkft@linaro.org>,
	Vignesh Raghavendra <vigneshr@ti.com>
Subject: Re: [PATCH net-next] net: build all switchdev drivers as modules when the bridge is a module
Date: Tue, 3 Aug 2021 14:33:04 +0200	[thread overview]
Message-ID: <CAK8P3a3xtC7p_iEcqLpL+uhCBGm31vrrCG5xFCxraCRZiyEWQA@mail.gmail.com> (raw)
In-Reply-To: <20210803115819.sdtdqhmfk5k4olip@skbuf>

On Tue, Aug 3, 2021 at 1:58 PM Vladimir Oltean <vladimir.oltean@nxp.com> wrote:
>
> On Tue, Aug 03, 2021 at 02:18:38PM +0300, Grygorii Strashko wrote:
> > In my opinion, the problem is a bit bigger here than just fixing the build :(
> >
> > In case, of ^cpsw the switchdev mode is kinda optional and in many cases
> > (especially for testing purposes, NFS) the multi-mac mode is still preferable mode.
> >
> > There were no such tight dependency between switchdev drivers and bridge core before and switchdev serviced as
> > independent, notification based layer between them, so ^cpsw still can be "Y" and bridge can be "M".
> > Now for mostly every kernel build configuration the CONFIG_BRIDGE will need to be set as "Y", or we will have
> > to update drivers to support build with BRIDGE=n and maintain separate builds for networking vs non-networking testing.
> > But is this enough? Wouldn't it cause 'chain reaction' required to add more and more "Y" options (like CONFIG_VLAN_8021Q)?
> >
> > PS. Just to be sure we on the same page - ARM builds will be forced (with this patch) to have CONFIG_TI_CPSW_SWITCHDEV=m
> > and so all our automation testing will just fail with omap2plus_defconfig.
>
> I didn't realize it is such a big use case to have the bridge built as
> module and cpsw as built-in.

I don't think anybody realistically cares about doing, I was only interested in
correctly expressing what the dependency is.

> I will send a patch that converts the
> switchdev_bridge_port_{,un}offload functions to simply emit a blocking
> switchdev notifier which the bridge processes (a la SWITCHDEV_FDB_ADD_TO_BRIDGE),
> therefore making switchdev and the bridge loosely coupled in order to
> keep your setup the way it was before.

That does sounds like it can avoid future build regressions, and simplify the
Kconfig dependencies, so that would probably be a good solution.

       arnd

  reply	other threads:[~2021-08-03 12:33 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-26 14:25 Vladimir Oltean
2021-07-27 10:15 ` Anders Roxell
2021-07-27 10:20 ` patchwork-bot+netdevbpf
2021-08-02 14:47 ` Arnd Bergmann
2021-08-03 11:18   ` Grygorii Strashko
2021-08-03 11:58     ` Vladimir Oltean
2021-08-03 12:33       ` Arnd Bergmann [this message]
2021-08-03 12:46         ` Grygorii Strashko

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