From owner-freebsd-hackers@FreeBSD.ORG Wed Jul 20 12:35:20 2011 Return-Path: Delivered-To: hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id EDED6106564A; Wed, 20 Jul 2011 12:35:20 +0000 (UTC) (envelope-from jhs@berklix.com) Received: from tower.berklix.org (tower.berklix.org [83.236.223.114]) by mx1.freebsd.org (Postfix) with ESMTP id 49A878FC16; Wed, 20 Jul 2011 12:35:19 +0000 (UTC) Received: from park.js.berklix.net (p5DCBEA02.dip.t-dialin.net [93.203.234.2]) (authenticated bits=0) by tower.berklix.org (8.14.2/8.14.2) with ESMTP id p6KCZABQ076567; Wed, 20 Jul 2011 12:35:10 GMT (envelope-from jhs@berklix.com) Received: from fire.js.berklix.net (fire.js.berklix.net [192.168.91.41]) by park.js.berklix.net (8.13.8/8.13.8) with ESMTP id p6KCZ76A028246; Wed, 20 Jul 2011 14:35:07 +0200 (CEST) (envelope-from jhs@berklix.com) Received: from fire.js.berklix.net (localhost [127.0.0.1]) by fire.js.berklix.net (8.14.4/8.14.4) with ESMTP id p6KCYvmT007475; Wed, 20 Jul 2011 12:35:02 GMT (envelope-from jhs@fire.js.berklix.net) Message-Id: <201107201235.p6KCYvmT007475@fire.js.berklix.net> To: John Baldwin From: "Julian H. Stacey" Organization: http://www.berklix.com BSD Unix Linux Consultancy, Munich Germany User-agent: EXMH on FreeBSD http://www.berklix.com/free/ X-URL: http://www.berklix.com In-reply-to: Your message "Wed, 20 Jul 2011 07:48:05 EDT." <201107200748.05786.jhb@freebsd.org> Date: Wed, 20 Jul 2011 14:34:57 +0200 Sender: jhs@berklix.com Cc: freebsd-hackers@freebsd.org, hackers@freebsd.org, Dan Nelson Subject: Re: Freebsd-7.4 + std gcc 4.2.1 fails to honour -march=i586 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: Wed, 20 Jul 2011 12:35:21 -0000 Hi, Reference: > From: John Baldwin > Date: Wed, 20 Jul 2011 07:48:05 -0400 > Message-id: <201107200748.05786.jhb@freebsd.org> John Baldwin wrote: > On Wednesday, July 20, 2011 7:33:26 am Julian H. Stacey wrote: > > What should FreeBSD do ? > > Add a comment to man gcc ... that -march=i586 is not > > enough, & feed the comment back to gcc project & see how > > they want to handle it ? > > No, this is not a GCC bug. If you want to use a single build machine that > will compile programs for other machines on a network to use, it must use the > lowest common denominator for its CPUTYPE in /etc/make.conf. > > The out-of-the-box crt files from a FreeBSD install will work fine on a 486 > and above, so can only get yourself into this quandry by building a new world > with a CPUTYPE (or similar CFLAGS) setting in /etc/make.conf that violates > this rule. > > You can fix your machine by fixing the CPUTYPE in your build machine and > building and installing a new world (do use NO_CLEAN=yes for your build, do a > full build). You will also want to rebuild any other binaries on this machine > that you share with other machines. > > -- > John Baldwin Hi John, Yes I realise all that now thanks. The point now is man gcc is misleading/ incomplete: "-march=cpu-type Generate instructions for the machine type cpu-type." Those instructions will not make a program that runs on a lesser CPU type without alternate crt for lesse CPU. CFLAGS in make.conf is fine for single developer/ host debugging, but is not appropriate for multi user multi make builds os src/ ports/ other Its seems just that gcc -march fails to select alternate crt. One gross ugly solution needing root would be to create chroots, but Too ugly. I suggest gcc via -march should also be used as a selection for sub dirs for crt ? & we should co-operate with gcc project on that, *BSD & *linux must all face same phenomena so lets not develop a non standard solution. Even if we're too lazy to do anything more, we should at least document it as a patch to man gcc. Cheers, Julian -- Julian Stacey, BSD Unix Linux C Sys Eng Consultants Munich http://berklix.com Reply below, not above; Indent with "> "; Cumulative like a play script. Format: Plain text. Not HTML, multipart/alternative, base64, quoted-printable.