From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Ungerer Subject: Re: [PATCH] m68k: Use generic strncpy_from_user(), strlen_user(), and strnlen_user() Date: Thu, 7 Jun 2012 21:10:19 +1000 Message-ID: <4FD08C1B.1090107@snapgear.com> References: <1338327216-15309-1-git-send-email-geert@linux-m68k.org> <20120530102226.GA28628@frolo.macqel> <20120530140444.GA10543@frolo.macqel> <4FCEF956.9090603@snapgear.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-m68k-owner@vger.kernel.org List-Id: linux-m68k@vger.kernel.org To: Geert Uytterhoeven Cc: Philippe De Muyter , Greg Ungerer , linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org Hi Geert, On 06/07/2012 03:46 AM, Geert Uytterhoeven wrote: > On Wed, Jun 6, 2012 at 8:31 AM, Greg Ungerer wrote: >> Yes, looks like that should have a "|| defined(CONFIG_CPU32)". >> (According to the CPU32 reference manual words and long words must >> be aligned on word boundaries.) >> >> I think something like CONFIG_CPU_HAS_NO_UNALIGNED makes sense. > > OK, doing that now... > > Then I saw arch/m68k/lib/memcpy.c. > > commit f230e80b423f6cb002015ab4771c06a53d5a2287 > ("m68k: fix memcpy to unmatched/unaligned source and dest on 68000") > > | The original 68000 processors cannot copy 16bit or larger quantities from > | odd addresses. All newer members of the 68k family (including ColdFire) > | can do this. > > So all Coldfires can do unaligned _reads_, but not unaligned _writes_ > (exceptions below)? This strikes me as odd. Maybe this has been wrong all along. I need to check further but in a little testing I did today I think it may well be that all ColdFire support unaligned reads and writes. >>>> I also think that the Coldfire 5272 can do unaligned accesses, but I >>>> cannot test that at the moment. >> >> >> According to the MCF5272 User Manual, "it supports misaligned data >> accesses ...". So it looks like it does. >> >> Having a CONFIG_CPU_HAS_NO_UNALIGNED looks like a really good solution >> then. We need to be able select it as required on individual CPU types. > > For now, I just make COLDFIRE select it, but we can move it to the individual > CPU types later. No matter what I find I still think this is the way to go. Thanks Greg ------------------------------------------------------------------------ Greg Ungerer -- Principal Engineer EMAIL: gerg@snapgear.com SnapGear Group, McAfee PHONE: +61 7 3435 2888 8 Gardner Close, FAX: +61 7 3891 3630 Milton, QLD, 4064, Australia WEB: http://www.SnapGear.com