Include contents of char array in flat binary file - c

Question

I am using flat binary files as external programs for my OS. When I compile them, like so:
gcc -Wall ctest.c -o ctest.bin -nostdlib -Wl,-Ttext=0x8000,-nostdlib -masm=intel
objcopy -O binary -j .text ctest.bin ctest
But doing this, the contents of the character array aren't put in the file. This is my code:
static volatile char string[4] = "Hi!\0";
static volatile char string2[15] = "Hello, World!\n\0";
int _start()
{
asm("mov eax, [string]");
asm("mov ebx, 0x00");
asm("int 0x01");
asm("mov eax, [string2]");
asm("mov ebx, 0x00");
asm("int 0x01");
return 0;
}
and when I run objdump (I ran it on the elf, but I verified it had the same code as this):
00008000 <_start>:
8000: 55 push ebp
8001: 89 e5 mov ebp,esp
8003: a1 70 90 00 00 mov eax,ds:0x9070
8008: bb 00 00 00 00 mov ebx,0x0
800d: cd 01 int 0x1
800f: a1 74 90 00 00 mov eax,ds:0x9074
8014: bb 00 00 00 00 mov ebx,0x0
8019: cd 01 int 0x1
801b: b8 00 00 00 00 mov eax,0x0
8020: 5d pop ebp
8021: c3 ret
As you can see, the text is nowhere to be found. I was hoping it would do something like this: string db "Hi!", 0 which I would do with nasm.
What should I do so it includes the characters in the output bin file without coding this in assembly?
Thanks in advance.

Answer 1

A binary executable file is typically divided into sections. Your strings have simply been placed into a different section than the code. This makes sense, since the code should be read-only but the strings have been declared non-const and volatile.

Answer 2

I figured out how to do it.
First I created a linker script like this (You can change phys to whatever address you want to load it at):
OUTPUT_FORMAT("binary")
ENTRY(start)
phys = 0x8000;
SECTIONS
{
.text phys : AT(phys) {
code = .;
*(.text)
*(.rodata)
. = ALIGN(0);
}
.data : AT(phys + (data - code))
{
data = .;
*(.data)
. = ALIGN(0);
}
.bss : AT(phys + (bss - code))
{
bss = .;
*(.bss)
. = ALIGN(0);
}
end = .;
}
Then compiled and linked the executable like this:
gcc -m32 -nostdlib -nostdinc -fno-builtin -o exec.o exec.c
ld -T link.ld -melf_i386 -o exec.bin exec.o