your code will have to reside in the 32-bit addressable memory

...So instructions like:

Code:

mov ah,sil
mov ah,[r8]    

are not encodable - fasm will show you a "prefix conflict" error message.

btw. i like fasm 1.64 more than 1.60 it has something about it and i don't think anyone will loose those 3 versions.

I want 1.64 to be the really final and fully featured version for x86-64, that's why I'm starting with 1.60.

[05:56:20]frekla@zeus elf64 $ ./fasm64 t.asm t ; file t /bin/true ; eu-readelf -h t; ./t
flat assembler  version 1.60 pre-alpha 5
2 passes, 132 bytes.
t:         ELF 64-bit LSB executable, AMD x86-64, version 1 (SYSV), statically linked, corrupted section header size
/bin/true: ELF 64-bit LSB executable, AMD x86-64, version 1 (SYSV), for GNU/Linux 2.4.1, dynamically linked (uses shared libs), stripped
ELF Header:
  Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
  Class:                             ELF64
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              EXEC (Executable file)
  Machine:                           AMD x86-64
  Version:                           1 (current)
  Entry point address:               0xbffff078
  Start of program headers:          64 (bytes into file)
  Start of section headers:          0 (bytes into file)
  Flags:                             
  Size of this header:               64 (bytes)
  Size of program header entries:    56 (bytes)
  Number of program headers entries: 1
  Size of section header entries:    0 (bytes)
  Number of section headers entries: 0 ([0] not available)
  Section header string table index: 0
    

format ELF64 executable

section readable writeable

msg db 'Hello 64-bit world!',0xA
msg_size = $-msg

section readable executable

entry $

        mov     eax,4
        mov     ebx,1
        mov     rcx,msg
        mov     edx,msg_size
        int     0x80

        mov     eax,1
        xor     ebx,ebx
        int     0x80