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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 87187C43218 for ; Fri, 26 Apr 2019 20:59:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 47FCA20869 for ; Fri, 26 Apr 2019 20:59:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b="1CU5hz3n" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726844AbfDZU7h (ORCPT ); Fri, 26 Apr 2019 16:59:37 -0400 Received: from vps0.lunn.ch ([185.16.172.187]:46043 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725966AbfDZU7h (ORCPT ); Fri, 26 Apr 2019 16:59:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=OCh7hT70whp/+unoMK2jqCVOcBFEvfKRG5b+VUOJD2I=; b=1CU5hz3nVs7ef8TMlXNAhWk/KB Vj2QqJiBl+W/gF58XyYvADOZDqrxI3rRwOJkNmnxn1f+4jFw6p00hkERkOWbAnIDt1iwvAumCTd5q Mjb48qJv4PHQhJctGvPCQIj/cav01dzGvhmBQTXpQSAb6Pt5h3oDcwjCAnLclCs+pJvY=; Received: from andrew by vps0.lunn.ch with local (Exim 4.89) (envelope-from ) id 1hK7w8-0004ty-B9; Fri, 26 Apr 2019 22:59:12 +0200 Date: Fri, 26 Apr 2019 22:59:12 +0200 From: Andrew Lunn To: Jakub Kicinski Cc: Esben Haabendal , netdev@vger.kernel.org, "David S. Miller" , Michal Simek , Yang Wei , YueHaibing , Luis Chamberlain , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/12] net: ll_temac: Fix support for 64-bit platforms Message-ID: <20190426205912.GI4041@lunn.ch> References: <20190426073231.4008-1-esben@geanix.com> <20190426073231.4008-4-esben@geanix.com> <20190426114013.333e62c8@cakuba.netronome.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190426114013.333e62c8@cakuba.netronome.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 26, 2019 at 11:40:13AM -0700, Jakub Kicinski wrote: > On Fri, 26 Apr 2019 09:32:22 +0200, Esben Haabendal wrote: > > The use of buffer descriptor APP4 field (32-bit) for storing skb pointer > > obviously does not work on 64-bit platforms. > > As APP3 is also unused, we can use that to store the other half of 64-bit > > pointer values. > > > > Contrary to what is hinted at in commit message of commit 15bfe05c8d63 > > ("net: ethernet: xilinx: Mark XILINX_LL_TEMAC broken on 64-bit") > > there are no other pointers stored in cdmac_bd. > > > > Signed-off-by: Esben Haabendal > > This is a bit strange, the driver stores the host's virtual address into > the HW descriptor? Hi Jukub This is reasonably common. You need some sort of cookie which links the hardware descriptor to the skbuf it points to. The hardware makes no use of it, it is just a cookie. Andrew