netdev - Re: [PATCH net-next V6 09/13] devlink: Add 'keep_link

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Message-ID: <vurqwfc5yk4aalycnx2xw2whyqsxffmkkdat3qrshmxwpzjewl@vogpn4nkjylg>
Date: Thu, 10 Jul 2025 14:45:14 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: Saeed Mahameed <saeed@...nel.org>
Cc: Jakub Kicinski <kuba@...nel.org>, 
	"David S. Miller" <davem@...emloft.net>, Paolo Abeni <pabeni@...hat.com>, 
	Eric Dumazet <edumazet@...gle.com>, Saeed Mahameed <saeedm@...dia.com>, netdev@...r.kernel.org, 
	Tariq Toukan <tariqt@...dia.com>, Gal Pressman <gal@...dia.com>, 
	Leon Romanovsky <leonro@...dia.com>, Jiri Pirko <jiri@...dia.com>, Simon Horman <horms@...nel.org>
Subject: Re: [PATCH net-next V6 09/13] devlink: Add 'keep_link_up' generic
 devlink device param

Thu, Jul 10, 2025 at 08:04:07AM +0200, saeed@...nel.org wrote:
>On 09 Jul 19:58, Jakub Kicinski wrote:
>> On Tue,  8 Jul 2025 20:04:51 -0700 Saeed Mahameed wrote:
>> > Devices that support this in permanent mode will be requested to keep the
>> > port link up even when driver is not loaded, netdev carrier state won't
>> > affect the physical port link state.
>> > 
>> > This is useful for when the link is needed to access onboard management
>> > such as BMC, even if the host driver isn't loaded.
>> 
>> Dunno. This deserves a fuller API, and it's squarely and netdev thing.
>> Let's not add it to devlink.
>
>I don't see anything missing in the definition of this parameter
>'keep_link_up' it is pretty much self-explanatory, for legacy reasons the
>netdev controls the underlying physical link state. But this is not
>true anymore for complex setups (multi-host, DPU, etc..).
>This is not different as BMC is sort of multi-host, and physical link
>control here is delegated to the firmware.
>
>Also do we really want netdev to expose API for permanent nic tunables ?
>I thought this is why we invented devlink to offload raw NIC underlying
>tunables.

Also, this devlink param is applicable even if you don't have any netdev
on top (e.g. you have only rdma device).


>
>Thanks,
>Saeed.
>
>