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Date: Fri, 8 Sep 2023 08:41:08 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Maxime Chevallier <maxime.chevallier@bootlin.com>
Cc: davem@davemloft.net, netdev@vger.kernel.org,
 linux-kernel@vger.kernel.org, Andrew Lunn <andrew@lunn.ch>, Eric Dumazet
 <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>, Florian Fainelli
 <f.fainelli@gmail.com>, Heiner Kallweit <hkallweit1@gmail.com>, Russell
 King <linux@armlinux.org.uk>, Vladimir Oltean <vladimir.oltean@nxp.com>,
 Oleksij Rempel <linux@rempel-privat.de>, =?UTF-8?B?Tmljb2zDsg==?= Veronese
 <nicveronese@gmail.com>, thomas.petazzoni@bootlin.com, Christophe Leroy
 <christophe.leroy@csgroup.eu>
Subject: Re: [RFC PATCH net-next 0/7] net: phy: introduce phy numbering
Message-ID: <20230908084108.36d0e23c@kernel.org>
In-Reply-To: <20230907092407.647139-1-maxime.chevallier@bootlin.com>
References: <20230907092407.647139-1-maxime.chevallier@bootlin.com>
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On Thu,  7 Sep 2023 11:23:58 +0200 Maxime Chevallier wrote:
>  - the netlink API would need polishing, I struggle a bit with finding
>    the correct netlink design pattern to return variale-length list of u32.

Think of them as a list, not an array.

Dump them one by one, don't try to wrap them in any way:
https://docs.kernel.org/next/userspace-api/netlink/specs.html#multi-attr-arrays
People have tried other things in the past:
https://docs.kernel.org/next/userspace-api/netlink/genetlink-legacy.html#attribute-type-nests
but in the end they add constraints and pain for little benefit.