os-k/boot/loader/loader.asm

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;=----------------------------------------------------------------------------=;
; GNU GPL OS/K ;
; ;
; Desc: Kernel (second stage) Loader for OS/K ;
; (x86_64 architecture only) ;
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; ;
; ;
; Copyright © 2018-2019 The OS/K Team ;
; ;
; This file is part of OS/K. ;
; ;
; OS/K is free software: you can redistribute it and/or modify ;
; it under the terms of the GNU General Public License as published by ;
; the Free Software Foundation, either version 3 of the License, or ;
; (at your option) any later version. ;
; ;
; OS/K is distributed in the hope that it will be useful, ;
; but WITHOUT ANY WARRANTY; without even the implied warranty of ;
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;
; GNU General Public License for more details. ;
; ;
; You should have received a copy of the GNU General Public License ;
; along with OS/K. If not, see <https://www.gnu.org/licenses/>. ;
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;=----------------------------------------------------------------------------=;
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%define DEBUG
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[BITS 32]
[global _start]
[ORG 0x100000] ; Where GRUB loads us.
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%include "boot/loader/multiboot/header.inc"
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;; Normal entry point, but a little bit unused since we never use it because...
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_start:
mov ax, cs ; correcting cs after the horrible far jump
mov ds, ax ; hm... And ds too
mov es, ax ; And es because it is jealous
;mov [Bootdrv], dl
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xor dl, dl
jmp 0x0000:_loader ; pas sûr
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;; Magnificent multiboot header for GRUB ------------------------------------ ;;
MB_header:
align 4
dd MB_HEADER_MAGIC
dd MB_HEADER_FLAGS
dd CHECKSUM
dd MB_header ; Header address
dd _start ; Address of code entry point
dd 00 ; (end of code) not necessary
dd 00 ; (bss) not necessary
dd MB_start ; entry address GRUB will start at
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;; Multiboot entry point for Grub ------------------------------------------- ;;
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MB_start:
mov esp, KERNEL_STACK ; Setup the stack
push 0 ; Reset EFLAGS
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popf
push eax ; 2nd argument is magic number
push ebx ; 1st argument multiboot info pointer
mov ecx, eax
call _loader
add esp, 8 ; Cleanup arguments "A la MIPS"
jmp Die ; Aufwiedersehen
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;; THE HOLES ---------------------------------------------------------------- ;;
Error:
mov dword [0xb8000], 0x4f524f45
mov dword [0xb8004], 0x4f3a4f52
mov dword [0xb8008], 0x4f204f20
mov byte [0xb800a], al
jmp Die
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Die:
cli
hlt ; die nooooow
;jmp 0xF000:0xFFF0
jmp $
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;; THE CODE ----------------------------------------------------------------- ;;
; ---------------------------------------------------------------------------- ;
; _loader ;
; ;
; This is the function that initiates the launch of OS/K. It verifies that ;
; Grub has properly loaded this loader and makes the appropriate setup so ;
; that the kernel will work properly ;
; ;
; Why this original design ? Because it works well and prevent us to cause ;
; triple faults by aligment error or too long jumps (yup, it can be a problem);
; ;
; ---------------------------------------------------------------------------- ;
_loader:
jmp lbegin
%include "boot/loader/multiboot/check.inc"
lbegin:
call MB_check
jmp lnext
%include "boot/loader/cpu/cpuid.inc"
lnext:
call Check_cpuid
call Is64Bits
jmp lnext2
%include "boot/loader/mem/structures.inc"
lnext2:
call Setup_paging
call Go64
jmp lnext3
%include "boot/loader/mem/management.inc"
lnext3:
mov dword [0xb8000], 0x2f4b2f4f
ret