notes.md

Resources on ELF:

• Making teensy programs
  • goes down to 45 bytes
• Undestanding ELF
  • Good high level overview / motivation explaner
• Overview of ELF and how to inspect it using tools
• Overview of basic format
• Spec for 64 bit
  • has 64 bit program section format
• Full spec - includes a lot of extra stuff we don't need Overview of ELF:
• Used for linking, dynamic libraries, executables
• Format
  • General format is File header, ... (normally nothing here), Program Headers (not needed for dyn. lib. or object files), ... (data, code, etc), section headers (not needed for executables)
  • 

Assembly:

; tiny.asm
BITS 64
GLOBAL _start
SECTION .bss
str:resb 1
SECTION .text
_start:
        mov     [str], byte 10
        mov     edx,1     ;message length
        mov     ecx,str    ;message to write
        mov     ebx,1       ;file descriptor (stdout)
        mov     eax,4       ;system call number (sys_write)
        int     0x80        ;call kernel
        mov     eax, 1
        mov     ebx, 42
        int     0x80