From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arvid Brodin Subject: Re: [RFC] net/hsr: Add support for IEC 62439-3 High-availability Seamless Redundancy Date: Fri, 6 Apr 2012 17:51:24 +0200 Message-ID: <4F7F10FC.3020308@enea.com> References: <20120403113751.21fd0b17@s6510.linuxnetplumber.net> <4F7CD4BC.4000006@enea.com> <20120404165559.5223ab95@s6510.linuxnetplumber.net> <20120404.202109.2046106039992811660.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: , , , To: David Miller Return-path: Received: from sestofw01.enea.se ([192.36.1.252]:18823 "HELO mx-3.enea.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1754168Ab2DFPvf (ORCPT ); Fri, 6 Apr 2012 11:51:35 -0400 In-Reply-To: <20120404.202109.2046106039992811660.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: David Miller wrote: > From: Stephen Hemminger > Date: Wed, 4 Apr 2012 16:55:59 -0700 > >> That isn't so bad, doing a memcpy versus a structure copy. > > GCC is going to inline the memcpy and thus we'll still do the > unaligned accesses. This change therefore won't fix the problem. Well, it does work for me, with gcc-4.2.2-compiled linux-2.6.37 running on an AVR32 board. Just out of curiosity, what's the mechanism behind this inline assignment that turns the memcpy into an unaligned access? If gcc is "smart" enough to detect a bunch of char * accesses and turn them into unaligned 32-bit accesses, isn't that a bug in gcc? Or will this only happen on archs which __HAVE_ARCH_MEMCPY? (But looking at a couple of arch/xxx/lib/string.c, these too seem to take alignment into account.) -- Arvid Brodin Enea Services Stockholm AB - since February 16 a part of Xdin in the Alten Group. Soon we will be working under the common brand Xdin. Read more at www.xdin.com.