1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/loader.s	Sun Nov 01 23:50:00 2009 +0100
     1.3 @@ -0,0 +1,35 @@
     1.4 +global loader           ; making entry point visible to linker
     1.5 +extern kmain             ; main is defined elsewhere
     1.6 +
     1.7 +; setting up the Multiboot header - see GRUB docs for details
     1.8 +MODULEALIGN equ  1<<0                   ; align loaded modules on page
     1.9 +; boundaries
    1.10 +MEMINFO     equ  1<<1                   ; provide memory map
    1.11 +FLAGS       equ  MODULEALIGN | MEMINFO  ; this is the Multiboot 'flag' field
    1.12 +MAGIC       equ    0x1BADB002           ; 'magic number' lets bootloader find the header
    1.13 +CHECKSUM    equ  -(MAGIC + FLAGS)       ; checksum required
    1.14 +
    1.15 +section .multiboot
    1.16 +align 4
    1.17 +MultiBootHeader:
    1.18 +   dd MAGIC
    1.19 +   dd FLAGS
    1.20 +   dd CHECKSUM
    1.21 +
    1.22 +; reserve initial kernel stack space
    1.23 +STACKSIZE equ 0x4000                  ; that's 16k.
    1.24 +
    1.25 +loader:
    1.26 +   mov esp, stack+STACKSIZE           ; set up the stack
    1.27 +   push eax                           ; pass Multiboot magic number
    1.28 +   push ebx                           ; pass Multiboot info structure
    1.29 +   call kmain                          ; call kernel proper
    1.30 +   cli
    1.31 +hang:
    1.32 +   hlt                                ; halt machine should kernel return
    1.33 +   jmp   hang
    1.34 +
    1.35 +section .bss
    1.36 +align 32
    1.37 +stack:
    1.38 +   resb STACKSIZE                     ; reserve stack on a quadword boundary