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[BITS 32]

global loader           ; making entry point visible to linker
extern _kmain            ; kmain is defined elsewhere

    SECTION .__mbHeader
    ; This part MUST be 4byte aligned, so we solve that issue using 'ALIGN 4'
    ALIGN 4
    mboot:
        ; Multiboot macros to make a few lines later more readable
        MULTIBOOT_PAGE_ALIGN        equ 1<<0
        MULTIBOOT_MEMORY_INFO       equ 1<<1
        MULTIBOOT_AOUT_KLUDGE       equ 1<<16
        MULTIBOOT_HEADER_MAGIC      equ 0x1BADB002
        MULTIBOOT_HEADER_FLAGS      equ MULTIBOOT_PAGE_ALIGN | MULTIBOOT_MEMORY_INFO | MULTIBOOT_AOUT_KLUDGE
        MULTIBOOT_CHECKSUM  equ -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
        EXTERN code, bss, end

        ; This is the GRUB Multiboot header. A boot signature
        dd MULTIBOOT_HEADER_MAGIC
        dd MULTIBOOT_HEADER_FLAGS
        dd MULTIBOOT_CHECKSUM

        ; AOUT kludge - must be physical addresses. Make a note of these:
        ; The linker script fills in the data for these ones!
        dd mboot
        dd code
        dd bss
        dd end
        dd loader

section .text
;align 4
;MultiBootHeader:
 ;  dd MAGIC
  ; dd FLAGS
  ; dd CHECKSUM
 
; reserve initial kernel stack space
STACKSIZE equ 0x4000                  ; that's 16k.
 
loader:
   mov esp, stack+STACKSIZE           ; set up the stack
   push eax                           ; pass Multiboot magic number
   push ebx                           ; pass Multiboot info structure
 
   call  _kmain                       ; call kernel proper
 
   cli
hang:
   hlt                                ; halt machine should kernel return
   jmp   hang
 
section .bss
align 4
stack:
   resb STACKSIZE                     ; reserve 16k stack on a doubleword boundary

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OUTPUT_FORMAT("pe-i386")
ENTRY(start)
phys = 0x00100000;
SECTIONS
{

   . = phys;
   /* .__mbHeader will begin @ 'phys' */
   .__mbHeader : AT ( ADDR( .__mbHeader ) ) {
      /* mboot = .;*/
      *(.__mbHeader)
   }
  .text : AT(ADDR(.text)) {
    code = .;
    *(.text)
    *(.rodata)
    . = ALIGN(4096);
  }
  .data : AT(ADDR(.text) + (data - code))
  {
    data = .;
    *(.data)
    . = ALIGN(4096);
  }
  .bss : AT(ADDR(.text) + (bss - code))
  {
    bss = .;
    *(.bss)
    . = ALIGN(4096);
  }
  end = .;
}

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nasm -f elf -o loader.o loader.asm
gcc -o kernel.o -c kernel.c -nostdlib -nostartfiles -nodefaultlibs
ld -T linker.ld -o kernel.bin loader.o kernel.o
copy /b stage1+stage2+pad+kernel.bin   floppy.img

bochs -q -f bochsrc.bxrc