From owner-cvs-all@FreeBSD.ORG  Sun Jun  4 20:27:54 2006
Return-Path: <owner-cvs-all@FreeBSD.ORG>
X-Original-To: cvs-all@FreeBSD.org
Delivered-To: cvs-all@FreeBSD.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id C21F816A61E;
	Sun,  4 Jun 2006 20:27:54 +0000 (UTC)
	(envelope-from marcel@FreeBSD.org)
Received: from repoman.freebsd.org (repoman.freebsd.org [216.136.204.115])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 92DA043D49;
	Sun,  4 Jun 2006 20:27:54 +0000 (GMT)
	(envelope-from marcel@FreeBSD.org)
Received: from repoman.freebsd.org (localhost [127.0.0.1])
	by repoman.freebsd.org (8.13.6/8.13.6) with ESMTP id k54KQDaC051695;
	Sun, 4 Jun 2006 20:26:13 GMT
	(envelope-from marcel@repoman.freebsd.org)
Received: (from marcel@localhost)
	by repoman.freebsd.org (8.13.6/8.13.4/Submit) id k54KQDRp051694;
	Sun, 4 Jun 2006 20:26:13 GMT (envelope-from marcel)
Message-Id: <200606042026.k54KQDRp051694@repoman.freebsd.org>
From: Marcel Moolenaar <marcel@FreeBSD.org>
Date: Sun, 4 Jun 2006 20:26:13 +0000 (UTC)
To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org
X-FreeBSD-CVS-Branch: HEAD
Cc: 
Subject: cvs commit: src/sys/geom geom_gpt.c
X-BeenThere: cvs-all@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: CVS commit messages for the entire tree <cvs-all.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-all>,
	<mailto:cvs-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/cvs-all>
List-Post: <mailto:cvs-all@freebsd.org>
List-Help: <mailto:cvs-all-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-all>,
	<mailto:cvs-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 04 Jun 2006 20:28:06 -0000

marcel      2006-06-04 20:26:13 UTC

  FreeBSD src repository

  Modified files:
    sys/geom             geom_gpt.c 
  Log:
  Fix unaligned memory accesses on Alpha and possible other platforms.
  By using a pointer to struct dos_partition, we implicitly tell the
  compiler that the pointer is 4-bytes aligned, even though we know
  that's not the case. The fact that we only dereference the pointer
  to access a byte-wide field (field dp_ptyp) is not a guarantee that
  the compiler will in fact use a byte-wide load. On some platforms
  it's more efficient to use long word or quad word loads and use
  bit-shifting and bit-masking to get the intended byte. On those
  platforms an misaligned load will be the result.
  The fix is to use byte-wide pointer arithmetic based on sizeof() and
  offsetof() to avoid invalid casts which avoids that the compiler
  makes invalid assumptions.
  
  Backtrace provided by: wilko@
  MFC after: 1 week
  
  Revision  Changes    Path
  1.38      +4 -3      src/sys/geom/geom_gpt.c