From owner-freebsd-amd64@FreeBSD.ORG Tue May 24 17:53:24 2005 Return-Path: X-Original-To: freebsd-amd64@freebsd.org Delivered-To: freebsd-amd64@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 6F47A16A41C for ; Tue, 24 May 2005 17:53:24 +0000 (GMT) (envelope-from obrien@NUXI.com) Received: from dragon.NUXI.org (trang.nuxi.com [66.93.134.19]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2EE9843D1F for ; Tue, 24 May 2005 17:53:24 +0000 (GMT) (envelope-from obrien@NUXI.com) Received: from dragon.NUXI.org (obrien@localhost [127.0.0.1]) by dragon.NUXI.org (8.13.3/8.13.3) with ESMTP id j4OHrMCo035291; Tue, 24 May 2005 10:53:22 -0700 (PDT) (envelope-from obrien@dragon.NUXI.org) Received: (from obrien@localhost) by dragon.NUXI.org (8.13.3/8.13.1/Submit) id j4OHrFdQ035284; Tue, 24 May 2005 10:53:15 -0700 (PDT) (envelope-from obrien) Date: Tue, 24 May 2005 10:53:15 -0700 From: "David O'Brien" To: =?unknown-8bit?Q?Jo=E3o_Carlos_Mendes_Lu=EDs?= Message-ID: <20050524175315.GA35171@dragon.NUXI.org> References: <42842F46.9040608@samsco.org> <4284FD37.2070009@jonny.eng.br> <20050519054630.GC68698@dragon.NUXI.org> <428CC670.50002@jonny.eng.br> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <428CC670.50002@jonny.eng.br> X-Operating-System: FreeBSD 6.0-CURRENT Organization: The NUXI BSD Group X-Pgp-Rsa-Fingerprint: B7 4D 3E E9 11 39 5F A3 90 76 5D 69 58 D9 98 7A X-Pgp-Rsa-Keyid: 1024/34F9F9D5 User-Agent: Mutt/1.5.9i Cc: freebsd-amd64@freebsd.org Subject: Re: Actual benefits of amd64 over i386 X-BeenThere: freebsd-amd64@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: freebsd-amd64@freebsd.org List-Id: Porting FreeBSD to the AMD64 platform List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 24 May 2005 17:53:24 -0000 On Thu, May 19, 2005 at 02:01:36PM -0300, Joo Carlos Mendes Lus wrote: > David O'Brien wrote: > > On Fri, May 13, 2005 at 04:17:11PM -0300, Joo Carlos Mendes Lus wrote: > > > >> What about a 64 bit kernel, and mixed mode (32bit and 64bit) > >>userland? Solaris does this, and it sounds efficient, from the comments > >>I've seen in this list. > > > > > > When Sparc went from 32-bits to 64-bits the calling ABI was not changed. > > Nor were the number of registers increased. So it is w/o a doubt that a > > 32-bit Sparc binary runs faster than a 64-bit one (abit 64-bit math and > > large memory). This is not true of AMD64 - the number of registers was > > doubled and the calling ABI changed and optimized. > > Would these benefits outcome the losses caused by bigger binaries? > Isn't it possible to use 64 bit registers in a 32 bit segment? Just > like i386 segments, where one could define the default register size... .. > > What is the difference of "i386 emulation" and "native 32 bit executables > > in amd64 arch"?? > > IMHO, the 32bit binaries prepared to run in amd64 32bit segments are > not the same as 32 binaries prepared to run in i386 mode. These "32bit > amd64 executables" would take advantage of the extra registers and 64 > bit extensions when possible. It is not possible to access the extra registers in 32-bit mode. -- -- David (obrien@FreeBSD.org)