From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261199AbTD1RBi (ORCPT ); Mon, 28 Apr 2003 13:01:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261200AbTD1RBi (ORCPT ); Mon, 28 Apr 2003 13:01:38 -0400 Received: from ns.suse.de ([213.95.15.193]:28935 "EHLO Cantor.suse.de") by vger.kernel.org with ESMTP id S261199AbTD1RBh (ORCPT ); Mon, 28 Apr 2003 13:01:37 -0400 Date: Mon, 28 Apr 2003 19:13:53 +0200 From: Andi Kleen To: Carl-Daniel Hailfinger Cc: Dave Hansen , Andi Kleen , Henti Smith , linux-kernel@vger.kernel.org, lse-tech@lists.sourceforge.net, Riley Williams Subject: Re: [Lse-tech] Re: maximum possible memory limit .. Message-ID: <20030428171353.GB1068@Wotan.suse.de> References: <20030424200524.5030a86b.bain@tcsn.co.za> <3EAD27B2.9010807@gmx.net> <20030428141023.GC4525@Wotan.suse.de> <3EAD5AC1.7090003@us.ibm.com> <3EAD5D90.7010101@gmx.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3EAD5D90.7010101@gmx.net> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > Cool. Sorry to be pestering about the 64-bit limits, but can we really > use 2^64 bytes of memory on ia64/ppc64/x86-64 etc.? (AFAIK, 64-bit > arches don't suffer from a small ZONE_LOWMEM.) No. The hardware have far smaller physical limits. Current AMD64 CPUs are limited to 40bit physical, 48bit virtal (the virtual limit per process in the current Linux kernel is 39bits) Itanium 2 afaik support a bit more 50bits (51 or 52, I forgot) physical, probably more virtual. Other 64bit architectures are somewhere inbetween. The actual limit in the machines is even less. You will have a hard time to find an affordable machine (64bit or not) with more than 8 DIMM slots. That's 16GB Max with 2GB DIMMs. -Andi