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