From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 2070 invoked by alias); 3 Apr 2008 09:02:01 -0000 Received: (qmail 2058 invoked by uid 22791); 3 Apr 2008 09:02:01 -0000 X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org (qpsmtpd/0.31) with ESMTP; Thu, 03 Apr 2008 09:01:43 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id m3391frP023490; Thu, 3 Apr 2008 05:01:41 -0400 Received: from zebedee.pink (vpn-14-7.rdu.redhat.com [10.11.14.7]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id m3391e4a007520; Thu, 3 Apr 2008 05:01:41 -0400 Message-ID: <47F49CF4.4060807@redhat.com> Date: Thu, 03 Apr 2008 10:27:00 -0000 From: Andrew Haley User-Agent: Thunderbird 2.0.0.12 (X11/20080213) MIME-Version: 1.0 To: Dennis Wassel CC: gcc-help@gcc.gnu.org Subject: Re: how to enable -m64 on x86-linux for building ATLAS References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact gcc-help-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-help-owner@gcc.gnu.org X-SW-Source: 2008-04/txt/msg00034.txt.bz2 Dennis Wassel wrote: > I've been trying to compile the ATLAS library on an 32-bit Linux > system with my self-compiled gcc 4.3.0, but this fails. > It boils down to the ATLAS config utility noticing that I have a > 64-bit processor and trying to compile some low-level stuff with -m64, > which doesn't work because I have not compiled in 64-bit support. [I > could force 32-bit mode, but I feel that 64-bit mode surely improves > performance, which is what ATLAS is for in the first place] > > Ok, so I try and recompile gcc, telling it that I do indeed have a > 64-bit processor, and it "profiledbootstrap"s itself merrily, until at > some point ld whines that it cannot find a compatible libc. > > Fine. I'm now going to try to build a 64-bit glibc (and worry where to > put it later, because I'm not root), and possible the full-fledged > binutils toolchain and so on, but now I feel this > chicken-and-egg-problem creeping up to me - wouldn't I need 64-bit > support in my compiler to create the corresponding glibc? > > D'oh! > > Any pointers, docs or howtos anyone? Much appreciated! In the 64-bit Linux system we have a backwards compatibility mode that allows us to run 32-bit applications. We don't have a corresponding 64-bit mode on 32-bit systems. Andrew.