From owner-freebsd-questions@FreeBSD.ORG  Fri Aug 13 22:58:02 2010
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 647851065674
	for <freebsd-questions@freebsd.org>;
	Fri, 13 Aug 2010 22:58:02 +0000 (UTC) (envelope-from yuri@rawbw.com)
Received: from shell0.rawbw.com (shell0.rawbw.com [198.144.192.45])
	by mx1.freebsd.org (Postfix) with ESMTP id 4F1C28FC0A
	for <freebsd-questions@freebsd.org>;
	Fri, 13 Aug 2010 22:58:02 +0000 (UTC)
Received: from eagle.syrec.org (stunnel@localhost [127.0.0.1])
	(authenticated bits=0)
	by shell0.rawbw.com (8.14.4/8.14.4) with ESMTP id o7DMvhj7031742;
	Fri, 13 Aug 2010 15:57:43 -0700 (PDT) (envelope-from yuri@rawbw.com)
Message-ID: <4C65CDE7.5010001@rawbw.com>
Date: Fri, 13 Aug 2010 15:57:43 -0700
From: Yuri <yuri@rawbw.com>
User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US;
	rv:1.9.1.10) Gecko/20100630 Thunderbird/3.0.5
MIME-Version: 1.0
To: Dan Nelson <dnelson@allantgroup.com>
References: <4C656E8F.8090105@rawbw.com>
	<20100813162429.GE18896@dan.emsphone.com> <4C65852B.807@rawbw.com>
	<20100813214457.GF18896@dan.emsphone.com>
In-Reply-To: <20100813214457.GF18896@dan.emsphone.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: freebsd-questions@freebsd.org
Subject: Re: Documentation on how to build 32bit applications on amd64?
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 13 Aug 2010 22:58:02 -0000

On 08/13/2010 14:44, Dan Nelson wrote:
> I think Anonymous is right, and that it's due to the /usr/include headers on
> amd64 not being 32-bit-mode aware.  So you end up with some structure
> members being sized for 64-bit machines instead of 32-bit.  I bet struct
> regex_t on your cross-compiled program is the same size as your native
> 64-bit program, where it should match your 32-bit program instead.  I took
> that "-B /usr/lib32" flag from /usr/src/Makefile.inc1 , where it builds the
> lib32 compat libraries, and it looks like it also temporarily installs a
> full 32-bit include directory and compiles against that with "-iprefix
> ${LIB32TMP}/usr/" .  You may have to install a full 32-bit tree somewhere
> and chroot to it to build, or look more closely at how buildworld compiles
> the lib32 stuff and mimic that, or submit patches to the base include files
> that make them 32 and 64-bit compatible depending on compiler flags.
>    

I think the best way is to modify headers to depend on compiler flags 
(__i386/__amd64). This makes such cross compile seamless for all future 
attempts to cross compile.
The problem I see is that there are currently 83 includes of 
<machine/...> headers from outside the machine/ hierarchy.
cd /usr/include && grep -r "<machine" * | grep include | grep -v ^machine
Looks like all of them should be made conditional on compiler flags like 
this:
...
#if !defined(__i386)
#include <machine/header.h>
#else
#include </usr/src/sys/i386/include/header.h>
#endif
...
Or rather pointing to some location (if any) where 32 bit headers would 
normally reside on amd64 host.
Do you think this is reasonable?
Should I make a patch, or maybe further discuss on hackers@?

Yuri