From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F0D9CC4332F for ; Mon, 7 Nov 2022 08:41:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=9dumSyZhUznQ8A4pu8O6B2Fcr3njGWouiInGxElAuZ4=; b=uQ9Fah8J5ZixOn E0CqVWII/u755e6VRg0dP/Lr3tOMYOc1QpukwYTwEQlGY/6uTcqAOKKp7SjAP8OEhSz3zFNQi6AEg PjxFQlF1/0DRCZpm8OX3u7TlAR6dGvhysYjCwv+fKlq42Q+vZ9anQLLs6mU+/n4eRkasux/YOzm1t 2/XkVHE+hcVgIQTZtASs2bmelPc2nuyewQnPXIGgdUH+PgAj/9ohVK+dpIkVZzxiMg3ro70qqDYPp 3+XeUuTW6XdeFGbvygd1xGHSkAsG4IK0ilFT1wgOlvtWqf354us1n3jo/M4rvObnuGUdG6RhQtZuf 9BjhfdeKfHWv1drrvMgA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1orxfr-00CtX0-6Q; Mon, 07 Nov 2022 08:40:07 +0000 Received: from relay10.mail.gandi.net ([217.70.178.230]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1orxfn-00CtUL-Vz for linux-arm-kernel@lists.infradead.org; Mon, 07 Nov 2022 08:40:06 +0000 Received: (Authenticated sender: maxime.chevallier@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id AE13B240012; Mon, 7 Nov 2022 08:39:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1667810395; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Kt3YaVgos6aTLVWYjMs61pa3ceG8lp2j8XYt+Ucplyw=; b=AscLybvqBkKKgJLxu4it0nKtw+XOslDBXsHBsvlHVxB0Quj8CJoOpqRBmXiqfOd1/kasH9 I+cRuyTQ77O+3UrGUe3ZGeH7rU1c/DtCrPXXS+URrPf5lzaNMrG7+Bc9qi70AWFk/HuaSt jolcAbhp1rSvg2qX53A0bk241bSR4UCNLi0r3AMKmZCI5JP75FU80j+GTBU53Iy1XyffQi Uv2CTDUq7j4BuVRIrD5Rb5nvrcN87Urg4Q7WbnybzhsxcFFSPae5Z7j42qmFbMKsj+HI3J vXojYdsYBdNtD5o2z/B8c6rgd+JXFd3YWUtUB46TeWGWJbN4757yjat0WVARgg== Date: Mon, 7 Nov 2022 09:39:50 +0100 From: Maxime Chevallier To: Jakub Kicinski Cc: davem@davemloft.net, Rob Herring , Krzysztof Kozlowski , Eric Dumazet , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, thomas.petazzoni@bootlin.com, Andrew Lunn , Florian Fainelli , Heiner Kallweit , Russell King , linux-arm-kernel@lists.infradead.org, Vladimir Oltean , Luka Perkov , Robert Marko , Andy Gross , Bjorn Andersson , Konrad Dybcio Subject: Re: [PATCH net-next v8 3/5] net: dsa: add out-of-band tagging protocol Message-ID: <20221107093950.74de3fa1@pc-8.home> In-Reply-To: <20221104200530.3bbe18c6@kernel.org> References: <20221104174151.439008-1-maxime.chevallier@bootlin.com> <20221104174151.439008-4-maxime.chevallier@bootlin.com> <20221104200530.3bbe18c6@kernel.org> Organization: Bootlin X-Mailer: Claws Mail 4.1.0 (GTK 3.24.34; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221107_004004_325261_FAFF1BCA X-CRM114-Status: GOOD ( 25.05 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hello Jakub, On Fri, 4 Nov 2022 20:05:30 -0700 Jakub Kicinski wrote: > On Fri, 4 Nov 2022 18:41:49 +0100 Maxime Chevallier wrote: > > This tagging protocol is designed for the situation where the link > > between the MAC and the Switch is designed such that the Destination > > Port, which is usually embedded in some part of the Ethernet > > Header, is sent out-of-band, and isn't present at all in the > > Ethernet frame. > > > > This can happen when the MAC and Switch are tightly integrated on an > > SoC, as is the case with the Qualcomm IPQ4019 for example, where > > the DSA tag is inserted directly into the DMA descriptors. In that > > case, the MAC driver is responsible for sending the tag to the > > switch using the out-of-band medium. To do so, the MAC driver needs > > to have the information of the destination port for that skb. > > > > Add a new tagging protocol based on SKB extensions to convey the > > information about the destination port to the MAC driver > > This is what METADATA_HW_PORT_MUX is for, you shouldn't have > to allocate a piece of memory for every single packet. Does this work with DSA ? The information conveyed in the extension is the DSA port identifier. I'm not familiar at all with METADATA_HW_PORT_MUX, should we extend that mechanism to convey the DSA port id ? I also agree that allocating data isn't the best way to go, but from the history of this series, we've tried 3 approaches so far : - Adding a new field to struct sk_buff, which isn't a good idea - Using the skb headroom, but then we can't know for sure is the skb contains a DSA tag or not - Using skb extensions, that comes with the cost of this memory allocation. Is this approach also incorrect then ? > Also the series doesn't build. Can you elaborate more ? I can't reproduce the build failure on my side, and I didn't get any reports from the kbuild bot, are you using a specific config file ? Thanks, Maxime _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel