Adrian Boeing <aboeing@xxxxxxxxx> writes:
> Thanks! You were infact correct, it does prefix with an '_'. This
> produces an executable of only 4kb now. (a 50% saving)
>
> When I try to execute the program I get a 'bus error', presumably
> because the cleanup/startup code is not run.
> I know this is getting a bit off the topic of GCC, but does anyone
> know what the stdlib does / what I need to do to make the program
> startup/cleanup nicely?
On debian, I can get it to work pretty well by doing:
(1) Call "_exit" instead of returning from main
(2) Use "-nostdlib" to avoid standard crt0 etc
(3) Use "-Wl,-emain" to tell the linker to use "main" as the entry point
(4) Explicitly link against libc (-nostdlib turns off the implicit
link against it), to at least get the definition of _exit
(5) Link statically with "-static"
Source file "small.c":
#include <unistd.h>
int main () { _exit (99); }
Compiling:
$ gcc -O2 -static -o small small.c -Wl,-emain -nostdlib -lc
$ ./small; echo $?
99
$ size small
text data bss dec hex filename
204 0 4 208 d0 small
-Miles
--
"Don't just question authority,
Don't forget to question me."
-- Jello Biafra
