Date: Mon, 27 Feb 2006 14:41:14 +0200 From: Ruslan Ermilov <ru@freebsd.org> To: Paul Koch <paul.koch@statseeker.com> Cc: freebsd-amd64@freebsd.org Subject: Re: Compiling using -m32 on a 64bit platform Message-ID: <20060227124114.GP42677@ip.net.ua> In-Reply-To: <200602271549.26372.paul.koch@statseeker.com> References: <200602271549.26372.paul.koch@statseeker.com>
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On Mon, Feb 27, 2006 at 03:49:26PM +1000, Paul Koch wrote:
> Hi,
>=20
> We have a locally written application which is currently deployed on=20
> i386, and we have recently ported it to amd64. Unfortunately, in our=20
> 64bit compile, some of our libraries and executables still need to be=20
> compiled for a 32bit architecture. Our application setup is a server=20
> (i386 or amd64 based) which communicates with remote network appliances=
=20
> (i386 based) and the server downloads various binaries to the remote=20
> appliances.
>=20
>=20
> The issues we have come across are to do with the size of various types.=
=20
> For example:
>=20
> int64_t
> - compiled on a 32bit machine is 64bits
> - compiled on a 64bit machine is 64bits
> - compiled on a 64bit machine with -m32 is 32bits !!
>=20
> Sample:
>=20
> #include <sys/types.h>
> #include <stdio.h>
>=20
> int
> main (int argc, char **argv)
> {
> printf ("sizeof (int64_t): %d\n", (int) sizeof (int64_t));
>=20
> return 0;
> }
>=20
> $ cc -Wall -m32 -L/usr/lib32 -B/usr/lib32 -o test_32 test.c
> $ cc -Wall -o test_64 test.c
>=20
> $ ./test_32
> sizeof (int64_t): 4
>=20
> $ ./test_64
> sizeof (int64_t): 8
>=20
You want to adopt the same approach that's used to compile 32-bit
runtime support on amd64. In the above, at the very minimum, you
miss the 32-bit (i386) versions of includes. The infrastructure
to allow users to build their 32-bit apps is not ready, so you'll
have to roll your own. Fortunately, this should be easy to do.
You can try it by using the make command from src/Makefile.inc1,
as will be shown by "make -f Makefile.inc1 -V LIB32MAKE", after
completing buildworld on amd64. For example,
: Script started on Mon Feb 27 14:37:44 2006
: $ uname -srm
: FreeBSD 7.0-CURRENT amd64
: $ cat Makefile
: LIB32MAKE!=3D cd /usr/src && ${MAKE} -f Makefile.inc1 -V LIB32MAKE
:=20
: .for target in depend all
: ${target}32:
: @cd ${.CURDIR} && ${LIB32MAKE} ${target}
: .endfor
:=20
: PROG=3D test_32
: SRCS=3D test.c
: NO_MAN=3D
:=20
: .include <bsd.prog.mk>
: $ make all32
: Warning: Object directory not changed from original /tmp
: cc -m32 -march=3Dk8 -mfancy-math-387 -DCOMPAT_32BIT -I/usr/obj/usr/src/l=
ib32/usr/include -L/usr/obj/usr/src/lib32/usr/lib32 -B/usr/obj/usr/src/li=
b32/usr/lib32 -O2 -fno-strict-aliasing -pipe -c test.c
: cc -m32 -march=3Dk8 -mfancy-math-387 -DCOMPAT_32BIT -I/usr/obj/usr/src/l=
ib32/usr/include -L/usr/obj/usr/src/lib32/usr/lib32 -B/usr/obj/usr/src/li=
b32/usr/lib32 -O2 -fno-strict-aliasing -pipe -o test_32 test.o=20
: $ file test_32
: test_32: ELF 32-bit LSB executable, Intel 80386, version 1 (FreeBSD), dyn=
amically linked (uses shared libs), not stripped
: $ ./test_32
: sizeof (int64_t): 8
: Script done on Mon Feb 27 14:38:03 2006
Cheers,
--=20
Ruslan Ermilov
ru@FreeBSD.org
FreeBSD committer
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