From owner-freebsd-hackers@FreeBSD.ORG Sun Dec 30 00:52:09 2007 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 544CA16A41A for ; Sun, 30 Dec 2007 00:52:09 +0000 (UTC) (envelope-from freebsd-hackers@m.gmane.org) Received: from ciao.gmane.org (main.gmane.org [80.91.229.2]) by mx1.freebsd.org (Postfix) with ESMTP id CEAA013C46E for ; Sun, 30 Dec 2007 00:52:08 +0000 (UTC) (envelope-from freebsd-hackers@m.gmane.org) Received: from list by ciao.gmane.org with local (Exim 4.43) id 1J8mPN-0006xI-NP for freebsd-hackers@freebsd.org; Sun, 30 Dec 2007 00:52:05 +0000 Received: from 78-1-83-158.adsl.net.t-com.hr ([78.1.83.158]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sun, 30 Dec 2007 00:52:05 +0000 Received: from ivoras by 78-1-83-158.adsl.net.t-com.hr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sun, 30 Dec 2007 00:52:05 +0000 X-Injected-Via-Gmane: http://gmane.org/ To: freebsd-hackers@freebsd.org From: Ivan Voras Date: Sun, 30 Dec 2007 01:51:54 +0100 Lines: 43 Message-ID: References: <20071229.122221.-432830441.imp@bsdimp.com> <4776d1d7.zI7kRv9uFoaBNKnQ%perryh@pluto.rain.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig80BE01B2E3758187A5AE944C" X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 78-1-83-158.adsl.net.t-com.hr User-Agent: Thunderbird 2.0.0.9 (Windows/20071031) In-Reply-To: <4776d1d7.zI7kRv9uFoaBNKnQ%perryh@pluto.rain.com> X-Enigmail-Version: 0.95.5 Sender: news Subject: Re: Architectures with strict alignment? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 30 Dec 2007 00:52:09 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig80BE01B2E3758187A5AE944C Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable perryh@pluto.rain.com wrote: > The degree to which a PowerPC imposes a strict alignment requirement > depends on both the particular processor model and the operation > being performed. >=20 > For ordinary integer arithmetic and logical operations, newer > PPC processors tend to be more tolerant (although misalignment > will typically carry a performance penalty). For the semaphore > primitives (lwarx/stwcx.) most PPC will require proper alignment > and some will fault if the operand address is cache-inhibited > (even though correctly aligned). How would it behave in operations like x =3D x + 1 where x is unaligned in memory? A RISC would have to load the value from memory, increment it and store it. I'm not particularly interested in slowdowns, just hard faults. --------------enig80BE01B2E3758187A5AE944C Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFHduuqldnAQVacBcgRAo1aAJ9JcQ32lVk0QfJL7kmPWXQjFO0/5QCaA+Z4 1h8NbZU3wcv8rs36rE3lhp8= =Cq8a -----END PGP SIGNATURE----- --------------enig80BE01B2E3758187A5AE944C--