From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [NET] IOC3: Switch hw checksumming to ethtool configurable. Date: Mon, 30 Jul 2007 16:06:54 -0400 Message-ID: <46AE44DE.8000107@garzik.org> References: <20070725113157.GA29416@linux-mips.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, Andrew Morton , "David S. Miller" , Herbert Xu To: Ralf Baechle Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:55816 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935071AbXG3UG6 (ORCPT ); Mon, 30 Jul 2007 16:06:58 -0400 In-Reply-To: <20070725113157.GA29416@linux-mips.org> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Ralf Baechle wrote: > Signed-off-by: Ralf Baechle applied to #upstream (2.6.24) > I've previously sent out this patch a long time ago. At that time I was > told NETIF_F_IP_CSUM wouldn't make any sense without NETIF_F_SG. IOC3's > S/G abilities are very limited; it can do upto three segments of which > the first one is upto 104 bytes and part of the packet's TX ring entry, > the second and 3rd ones can be anywhere in the 64-bit PCI address space > but may not cross a 16kB page boundary. So setting NETIF_F_SG isn't > really an option unless the IOC3 was going to linearize any packet it > can't cope with itself. > > So the big question, does NETIF_F_IP_CSUM without NETIF_F_SG make sense? Conventional wisdom has always been that NETIF_F_SG is required if NETIF_F_*CSUM is present, and vice versa. I admit I've not verified this in the past year or two. Jeff