From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philippe De Muyter Subject: Re: [PATCH] m68knommu: allow ColdFire CPUs to use unaligned accesses Date: Fri, 8 Jun 2012 12:39:31 +0200 Message-ID: <20120608103931.GA26964@frolo.macqel> References: <1339134180-13630-1-git-send-email-gerg@snapgear.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mailrelay020.isp.belgacom.be ([195.238.6.95]:56153 "EHLO mailrelay020.isp.belgacom.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932682Ab2FHKjf (ORCPT ); Fri, 8 Jun 2012 06:39:35 -0400 Content-Disposition: inline In-Reply-To: <1339134180-13630-1-git-send-email-gerg@snapgear.com> Sender: linux-m68k-owner@vger.kernel.org List-Id: linux-m68k@vger.kernel.org To: gerg@snapgear.com Cc: linux-m68k@vger.kernel.org, uclinux-dev@uclinux.org, Greg Ungerer On Fri, Jun 08, 2012 at 03:43:00PM +1000, gerg@snapgear.com wrote: > From: Greg Ungerer >=20 > All current ColdFire CPUs are able to support unaligned memory access= es. > So remove the CONFIG_CPU_HAS_NO_UNALIGNED option selection for ColdFi= re. >=20 > It seems that the current restriction was inherrited from the early n= on-MMU > support for the basic 68000 proecssors - which do not support unalign= ed > accesses. It seems that the first ColdFires needed the restriction : I read in the "MCF5200 ColdFire Family Programmer=E2=80=99s Reference M= anual" : The ColdFire processor default configuration supports word- and longword-sized operand references on 0-modulo-2 and 0-modulo-4 addresses, respectively. All other references are defined as misaligned accesses. Any attempt to access a misaligned operand generates an address-error exception, unless the optional hardware module for handling misalignment is present. This misalignment module converts any misaligned operand references into a series of aligned bus cycles to access the data. The existence of the misalignment module is implementation-dependent and is documented in the appropriate ColdFire user=E2=80=99s manual. Philippe