From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BBE3D10F1; Wed, 17 Sep 2025 21:19:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758143954; cv=none; b=iiVRKFYvpDWYBmSQIhQ/3PfuPMi/J1woOBJ4QW/ygzhm+/kecFnVeTwHRzZYA5fOEAvaEI6bQbQKWkwWws4xvE+ywpuoqKkgaRGPxcjzF50fQ+TT1tXX57HZoYxA+iPsK9ruuTi+b5uBSYgWCna+tyjyOjDmn3jnUCNwBolMrUs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758143954; c=relaxed/simple; bh=2hX6h0lZi6Wvimj0InNgEZYJuaAotowTDFW8fY0ZYi4=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=eKU9UfcsJZlrLB7FnoKV0V4Ya0IrmZaIkQoA0HIvI++IZhgN3uO7IXjw0/nRFQwO4PkTCsbpwLEnovJB5t6fDIYgSYv0YVbirObwhuWqCVVrJHqWJlseGoZ/I4qjWb7vIt40hEVlhOj0abluPZX72I6Wf3MvB+5fHd6R/qm9bvw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZD1FJCNp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZD1FJCNp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BF6EEC4CEE7; Wed, 17 Sep 2025 21:19:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758143954; bh=2hX6h0lZi6Wvimj0InNgEZYJuaAotowTDFW8fY0ZYi4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ZD1FJCNpKn9xWANveD4AS6EmPXZFEpw7jlIGhgK4rilzcrgLC1jInQGIz+azQjvHP MCpXKR1a/ph8hoHB8YzUP1H+IUOCxCNPXzQ4iBUixHYprRbz4TdaGVQzryWSLDa97v FMMREQoLBH7T7wsiqZwIC8XnvaGcrKJeJV0YHct8H13TAknPLPjvQunW7MT0jYpSau z89wOoPrjtkCkjO8BbUegUaClOfK+pXnhrHKfHyU1IxLQhxp4Qdoj9zvv2xPxdaETS eIO5i59siokBOQZ4JuHSLLZvhE7f/LNQvgbp2M4rl/taAxE4bw9Fh9E1mPwxRxjT2C gVwR9t9xM/ujA== Date: Wed, 17 Sep 2025 14:19:12 -0700 From: Jakub Kicinski To: Kory Maincent Cc: Oleksij Rempel , Andrew Lunn , "David S. Miller" , Eric Dumazet , Paolo Abeni , Jiri Pirko , Simon Horman , Jonathan Corbet , Donald Hunter , kernel@pengutronix.de, Dent Project , Thomas Petazzoni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Maxime Chevallier , linux-doc@vger.kernel.org, Kyle Swenson Subject: Re: [PATCH net-next v3 0/5] net: pse-pd: pd692x0: Add permanent configuration management support Message-ID: <20250917141912.314ea89b@kernel.org> In-Reply-To: <20250917114655.6ed579eb@kmaincent-XPS-13-7390> References: <20250915-feature_poe_permanent_conf-v3-0-78871151088b@bootlin.com> <20250916165440.3d4e498a@kernel.org> <20250917114655.6ed579eb@kmaincent-XPS-13-7390> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 17 Sep 2025 11:46:55 +0200 Kory Maincent wrote: > > On Mon, 15 Sep 2025 19:06:25 +0200 Kory Maincent wrote: > > > This patch series introduces a new devlink-conf uAPI to manage device > > > configuration stored in non-volatile memory. This provides a standardized > > > interface for devices that need to persist configuration changes across > > > reboots. The uAPI is designed to be generic and can be used by any device > > > driver that manages persistent configuration storage. > > > > > > The permanent configuration allows settings to persist across device > > > resets and power cycles, providing better control over PSE behavior > > > in production environments. > > > > I'm still unclear on the technical justification for this. > > "There's a tool in another project which does it this way" > > is not usually sufficient upstream. For better or worse we > > like to re-implement things from first principles. > > > > Could you succinctly explain why "saving config" can't be implemented > > by some user space dumping out ethtool configuration, saving it under > > /etc, and using that config after reboot. A'la iptables-save / > > iptables-restore? > > I think the only reason to save the config in the NVM instead of the userspace > is to improve boot time. As Oleksij described: > > I can confirm a field case from industrial/medical gear. Closed system, > > several modules on SPE, PoDL for power. Requirement: power the PDs as > > early as possible, even before Linux. The box boots faster if power-up > > and Linux init run in parallel. In this setup the power-on state is > > pre-designed by the product team and should not be changed by Linux at > > runtime. > > He told me that he also had added support for switches in Barebox for the > same reason, the boot time. I don't know if it is a reasonable reason to add it > in Linux. Right, subjectively I focused on the last sentence of Oleksij's reply. I vote we leave it out for now.