We develop software and are beginning a slow transition from 32 bit
applications
to their 64 bit equivalents. During this period it will be necessary to
build
programs targeted for both environments using the x86-64 machines for
development.
here is a simple/small "application", sizes.c:
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char **argv)
{
printf("Various sizes:\n");
printf(" short = %d\n", sizeof(short));
printf(" int = %d\n", sizeof(int));
printf(" long = %d\n", sizeof(long));
printf(" float = %d\n", sizeof(float));
printf(" double = %d\n", sizeof(double));
return 0;
}
if I build it using:
gcc -m32 -Wall -osizes sizes.c
there are no warnings or complaints and a functioning 32 bit
program runs, giving the size of a long as 4 bytes. (Of course
without the m32 flag the size of long is 8 bytes.)
if I try to do the equivalent in two steps:
gcc -c -m32 -Wall sizes.c
gcc -osizes -Wl,-m,elf_i386 sizes.o
the result is:
/usr/bin/ld: skipping incompatible
/usr/lib/gcc/x86_64-redhat-linux/4.1.2/libgcc.a when searching for -lgcc
/usr/bin/ld: skipping incompatible
/usr/lib/gcc/x86_64-redhat-linux/4.1.2/libgcc.a when searching for -lgcc
/usr/bin/ld: cannot find -lgcc
collect2: ld returned 1 exit status
there is some confusion in the man pages as to whether the correct 32
bit emulation is elf_i386 or i386linux so:
gcc -osizes -Wl,-m,i386linux sizes.o
gives result:
/usr/bin/ld: unrecognized option '--eh-frame-hdr'
/usr/bin/ld: use the --help option for usage information
collect2: ld returned 1 exit status
since the single line command works it seems that there must be a way to
get the job done.
This becomes important when there are many source files and use of a
traditional
makefile is involved where compiling and linking are separate steps.
Thanks in advance for reading this,
roger wells
--
Roger Wells, P.E.
SAIC
221 Third St
Newport, RI 02840
401-847-4210 (voice)
401-849-1585 (fax)
roger.k.wells at saic.com