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annotate loader.s @ 0:99db6262c157

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initial commit with code from http://wiki.osdev.org/Bare_bones
author meillo@marmaro.de
date Sun, 01 Nov 2009 23:50:00 +0100
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99db6262c157 initial commit with code from http://wiki.osdev.org/Bare_bones
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1 global loader ; making entry point visible to linker
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2 extern kmain ; main is defined elsewhere
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3
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4 ; setting up the Multiboot header - see GRUB docs for details
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5 MODULEALIGN equ 1<<0 ; align loaded modules on page
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6 ; boundaries
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7 MEMINFO equ 1<<1 ; provide memory map
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8 FLAGS equ MODULEALIGN | MEMINFO ; this is the Multiboot 'flag' field
99db6262c157 initial commit with code from http://wiki.osdev.org/Bare_bones
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9 MAGIC equ 0x1BADB002 ; 'magic number' lets bootloader find the header
99db6262c157 initial commit with code from http://wiki.osdev.org/Bare_bones
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10 CHECKSUM equ -(MAGIC + FLAGS) ; checksum required
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11
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12 section .multiboot
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13 align 4
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14 MultiBootHeader:
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15 dd MAGIC
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16 dd FLAGS
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17 dd CHECKSUM
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18
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19 ; reserve initial kernel stack space
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20 STACKSIZE equ 0x4000 ; that's 16k.
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99db6262c157 initial commit with code from http://wiki.osdev.org/Bare_bones
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22 loader:
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23 mov esp, stack+STACKSIZE ; set up the stack
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24 push eax ; pass Multiboot magic number
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25 push ebx ; pass Multiboot info structure
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26 call kmain ; call kernel proper
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27 cli
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28 hang:
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29 hlt ; halt machine should kernel return
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30 jmp hang
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31
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32 section .bss
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33 align 32
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34 stack:
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35 resb STACKSIZE ; reserve stack on a quadword boundary