From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Hartkopp Subject: Re: [RFC] can: Introducing CANFD for af_can & can-raw Date: Wed, 21 Mar 2012 16:26:57 +0100 Message-ID: <4F69F341.20504@hartkopp.net> References: <20120321091055.GA433@vandijck-laurijssen.be> <20120321110502.GA3372@vandijck-laurijssen.be> <4F69BEE3.2040705@pengutronix.de> <20120321120846.GB3372@vandijck-laurijssen.be> <4F69CA74.3020607@pengutronix.de> <4F69D5D2.5080003@hartkopp.net> <20120321135339.GB6428@vandijck-laurijssen.be> <4F69EA75.1070202@hartkopp.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mo-p00-ob.rzone.de ([81.169.146.161]:46142 "EHLO mo-p00-ob.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755120Ab2CUP07 (ORCPT ); Wed, 21 Mar 2012 11:26:59 -0400 In-Reply-To: <4F69EA75.1070202@hartkopp.net> Sender: linux-can-owner@vger.kernel.org List-ID: To: Kurt Van Dijck Cc: linux-can@vger.kernel.org On 21.03.2012 15:49, Oliver Hartkopp wrote: > On 21.03.2012 14:53, Kurt Van Dijck wrote: >>> IMO we need to introduce a new struct canfd_frame >> IMO we need not to introduce a new struct since they are logically equivalent. >> >> I created an old can20b_frame just to compute the sizeof. >> I'd go for a combined can_frame that could hold both. > > > No. You only think of CAN_RAW. There might be a way to do it with CAN_RAW but > changing an exported visible userspace structure breaks the ABI. > > Expect that we can never change struct can_frame as this is written into stone. Answering myself, but here's a very recent statement from Linus focussing binary compatibility: http://thread.gmane.org/gmane.linux.kernel/1245999/focus%3D1264170 Indeed we once broke the ABI when fixing the EFF/SFF filters reported by yourself. But this was a very simple thing in one bit that has not been handled correctly in opposite to change struct can_frame ... Regards, Oliver