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From: Grygorii Strashko <>
To: Arnd Bergmann <>,
	Vladimir Oltean <>
Cc: Networking <>,
	Jakub Kicinski <>,
	"David S. Miller" <>,
	Naresh Kamboju <>,
	Lars Povlsen <>,
	Steen Hegelund <>,
	Microchip Linux Driver Support <>,
	Florian Fainelli <>,
	Andrew Lunn <>,
	Vivien Didelot <>,
	Ido Schimmel <>, Jiri Pirko <>,
	Roopa Prabhu <>,
	Nikolay Aleksandrov <>,
	Linux Kernel Functional Testing <>,
	Vignesh Raghavendra <>
Subject: Re: [PATCH net-next] net: build all switchdev drivers as modules when the bridge is a module
Date: Tue, 3 Aug 2021 15:46:26 +0300	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 03/08/2021 15:33, Arnd Bergmann wrote:
> On Tue, Aug 3, 2021 at 1:58 PM Vladimir Oltean <> 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.

Yes. it sounds good, thank you.
Just a thought - might be good to follow switchdev_attr approach (extendable), but in the opposite direction as, I feel,
more notification dev->bridge might be added in the future.

Best regards,

      reply	other threads:[~2021-08-03 12:46 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
2021-08-03 12:46         ` Grygorii Strashko [this message]

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