The HelloWorld application is much simpler than the Windows one. Just put parameters into registers from %eax to %edx, and trigger a 0x80 interrupt.
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 |
# gcc -nostdlib syscall_linux.s -o syscall_linux .global _start .text _start: # write(1, message, 13) mov $4, %eax # system call 4 is write mov $1, %ebx # file handle 1 is stdout mov $message, %ecx # address of string to output mov $13, %edx # number of bytes to write int $0x80 # invoke system call # exit(0) mov $1, %eax # system call 1 is exit xor %ebx, %ebx # return 0 int $0x80 # invoke system call message: .ascii "Hello World!\n" |