main.c

// gcc -nostdlib main.c

inline static
void write_syscall(int fd, const void *buf, unsigned int count)
{
    asm("movq $1, %rax");
    asm("syscall");
}

inline static
void exit_syscall(int code)
{
    asm("movq $60, %rax");
    asm("syscall");
}

void _start()
{
    char message[] = "Hello, World\n";
    write_syscall(1, message, sizeof(message));
    exit_syscall(0);
}