Is there a way to get gcc to output raw binary?

Try this out:

$ gcc -c test.c     $ objcopy -O binary -j .text test.o binfile

You can make sure it's correct with objdump:

$ objdump -d test.o test.o:     file format pe-i386Disassembly of section .text:00000000 <_f>:   0:   55                      push   %ebp   1:   89 e5                   mov    %esp,%ebp   3:   83 ec 04                sub    $0x4,%esp   6:   8b 45 08                mov    0x8(%ebp),%eax   9:   0f af 45 08             imul   0x8(%ebp),%eax   d:   89 45 fc                mov    %eax,-0x4(%ebp)  10:   8b 45 fc                mov    -0x4(%ebp),%eax  13:   83 c0 02                add    $0x2,%eax  16:   c9                      leave    17:   c3                      ret  

And compare it with the binary file:

$ hexdump -C binfile 00000000  55 89 e5 83 ec 04 8b 45  08 0f af 45 08 89 45 fc  |U......E...E..E.|00000010  8b 45 fc 83 c0 02 c9 c3                           |.E......|00000018

You can use objcopy to pull the text segment out of the .o file or the a.out file.

$ cat q.cf() {}$ cc -S -O q.c$ cat q.s        .file   "q.c"        .text.globl f        .type   f, @functionf:        pushl   %ebp        movl    %esp, %ebp        popl    %ebp        ret        .size   f, .-f        .ident  "GCC: (Ubuntu 4.3.3-5ubuntu4) 4.3.3"        .section        .note.GNU-stack,"",@progbits$ cc -c -O q.c$ objcopy -O binary q.o q.bin$ od -X q.bin0000000 5de58955 000000c30000005$ objdump -d q.oq.o:     file format elf32-i386Disassembly of section .text:00000000 <f>:   0:   55                      push   %ebp   1:   89 e5                   mov    %esp,%ebp   3:   5d                      pop    %ebp   4:   c3                      ret    

You can pass options to the linker directly with -Wl,<linker option>

The relevant documentation is copied below from the man gcc

-Wl,option
Pass option as an option to the linker. If option contains commas, it is split into multiple options at the commas. You can use this syntax to pass an argument to the option. For example, -Wl,-Map,output.map passes -Map output.map to the linker. When using the GNU linker, you can also get the same effect with -Wl,-Map=output.map.

So when compiling with gcc if you pass -Wl,--oformat=binary you will generate a binary file instead of the elf format. Where --oformat=binary tells ld to generate a binary file.

This removes the need to objcopy separately.

Note that --oformat=binary can be expressed as OUTPUT_FORMAT("binary") from within a linker script. If you want to deal with flat binaries, there's a big chance that you would benefit from high level of control that linker scripts provide.