From owner-freebsd-amd64@FreeBSD.ORG Sat Apr 8 06:05:59 2006 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 F330A16A401 for ; Sat, 8 Apr 2006 06:05:58 +0000 (UTC) (envelope-from jmg@hydrogen.funkthat.com) Received: from hydrogen.funkthat.com (gate.funkthat.com [69.17.45.168]) by mx1.FreeBSD.org (Postfix) with ESMTP id 90E1A43D53 for ; Sat, 8 Apr 2006 06:05:57 +0000 (GMT) (envelope-from jmg@hydrogen.funkthat.com) Received: from hydrogen.funkthat.com (4ipc6fsnj1hs9kri@localhost.funkthat.com [127.0.0.1]) by hydrogen.funkthat.com (8.13.4/8.13.3) with ESMTP id k3865seq005150; Fri, 7 Apr 2006 23:05:54 -0700 (PDT) (envelope-from jmg@hydrogen.funkthat.com) Received: (from jmg@localhost) by hydrogen.funkthat.com (8.13.4/8.13.3/Submit) id k3865qUp005149; Fri, 7 Apr 2006 23:05:52 -0700 (PDT) (envelope-from jmg) Date: Fri, 7 Apr 2006 23:05:52 -0700 From: John-Mark Gurney To: Astrodog Message-ID: <20060408060552.GG72485@funkthat.com> Mail-Followup-To: Astrodog , freebsd-amd64@freebsd.org References: <20060407172618.GC72485@funkthat.com> <200604072116.k37LGQhQ071637@lurza.secnetix.de> <2fd864e0604072236p2ee54649ld9d328f429005d6a@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2fd864e0604072236p2ee54649ld9d328f429005d6a@mail.gmail.com> User-Agent: Mutt/1.4.2.1i X-Operating-System: FreeBSD 5.4-RELEASE-p6 i386 X-PGP-Fingerprint: B7 EC EF F8 AE ED A7 31 96 7A 22 B3 D8 56 36 F4 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html Cc: freebsd-amd64@freebsd.org Subject: Re: extreme mem usage under amd64 arch ? X-BeenThere: freebsd-amd64@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: John-Mark Gurney List-Id: Porting FreeBSD to the AMD64 platform List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 08 Apr 2006 06:05:59 -0000 Astrodog wrote this message on Sat, Apr 08, 2006 at 13:36 +0800: > On 4/8/06, Oliver Fromme wrote: > > I guess this is the most important reason: If ints were 64 > > bits, there would be no easy way to handle 32 bit entities. > > Not being able to handle 32 bit objects with a native data > > type whould be a major problem, especially for an OS kernel, > > I think. > > > Can an AMD64 processor actually handle 32 bits of data natively, or > does it just knock off the last 32 bits of a 64-bit version, when its > not in long mode? yes, it can... infact it defaults to 32bits unless a prefix is provided to access 64bit registers... (assuming a mode that 64bit registers are accessable).. Though as w/ most processors, the upper 32bits are still around, just on 32bit operations they are ignored... -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."