From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 F39C51C862D; Tue, 9 Jun 2026 02:02:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780970571; cv=none; b=iMve75GnLGVh4q7tnHEY70lrsThC3GRWLUiFWdgQIDOMfYKqPGYFewXLBgbBs8ws2clrDJQdnoIE7Hpa5+MAMStgIHA9rAsAo+5tx/EzFPifzv/HQeLRkItT6dZLP+8G196194qg0xXlKTJimVVuOXaenEViczar0F7ntbxvSWg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780970571; c=relaxed/simple; bh=4DLg5vFKr/MdOkVPkyqAhn7lKmQqQs6z0SssMQO3OBI=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=TtJJIFZiIh4M6R1B236CoCaNsh+akH6dCJ+C9L95ktZut2jE28CfSizjb94GQlINqzdKU5ZUO5P/w+rg854i4Wjk007WhgTr2UDulc5llEVCFThv6Yko29TbcXxYcpdwGnwfKKmxN+tE40KNKdC2ZopR7xJor6Fh4jxVyHfdyRE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Qzob7YTg; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Qzob7YTg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 32AC31F00893; Tue, 9 Jun 2026 02:02:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780970570; bh=ZFfblUl+2BQQI/iDMzj3upvP5Re2fQBphQvxi0LqbQE=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=Qzob7YTgxwW1JDklJPVBuLx+oULb2gpMzIrmnXRlsSQyEDsu9pwIO0/0gU/BX6RqP 2dbYELUdDToLqw9IrIXfwgbnPwLXKKxsfv62BCaelmjiBg+QSbAFwIpJ3G14SZXc88 aClmZfCbakeN9+f/6IHG46yJCeuhINtqx6niWnBf88hh970TndGFgeXYFAmkDAW/EP jkpnwjQ8p+ex43DkxbbXHKBm2a2atEHVq7BtW4XjHji+1GZMpL936y09Hqae/Jghhq n5wLuMDcRcvcEAuTita/JgWRkN4TQe2sUNKMFMAmVdeCEqL7q6CwPB6nGZNPYs8IM6 NwZq6nTs/bduw== Date: Mon, 8 Jun 2026 19:02:49 -0700 From: Jakub Kicinski To: Ratheesh Kannoth Cc: , , , , , , , , , Subject: Re: [PATCH v19 net-next 1/9] octeontx2-af: Enforce single RVU AF probe Message-ID: <20260608190249.03f4d6e7@kernel.org> In-Reply-To: References: <20260605063245.3553861-1-rkannoth@marvell.com> <20260605063245.3553861-2-rkannoth@marvell.com> <20260608154014.1b7c8be1@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Tue, 9 Jun 2026 07:13:40 +0530 Ratheesh Kannoth wrote: > On 2026-06-09 at 04:10:14, Jakub Kicinski (kuba@kernel.org) wrote: > > On Fri, 5 Jun 2026 12:02:37 +0530 Ratheesh Kannoth wrote: =20 > > > There is only one admin-function PCI device per system. > > > Reject any additional AF probe with -EBUSY so the driver model matches > > > hardware and automated reviewers can rely on a single bound instance.= =20 > > > > Could you point me to a PCI networking driver written in the last two > > decades which would have this sort of limitation? > > > > At the very least you need to explain in the commit message **why** > > correctly handling multiple devices in a system is beyond your > > abilities. =20 >=20 > The comparison to a generic PCI networking driver isn't quite applicable > here. The RVU AF (Administrative Function) is not a standard NIC PF =E2= =80=94 > it is a system-level resource manager that owns a single, shared set of > AF registers across the entire RVU subsystem. The hardware spec is > explicit on this: "RVU has a single, common set of AF registers. >=20 > This is fundamentally different from a multi-port NIC where each PF is > an independent, symmetric instance. In the RVU model, there is exactly > one AF device per SoC, and all other PFs communicate with it > via mailboxes rather than accessing AF registers directly. Allowing a > second AF probe would mean two driver instances racing to manage the > same global hardware state =E2=80=94 provisioning LFs, configuring > NPC/NIX/NPA =E2=80=94 with no hardware arbitration between them. I asked you before - is this a driver for a PCIe devices? You said "yes". If so what prevents the user from plugging two such devices into one system?