diff --git a/boot/folder.desc b/boot/folder.desc
index fc76abf..3eb3f85 100644
--- a/boot/folder.desc
+++ b/boot/folder.desc
@@ -27,12 +27,13 @@ This folder contains the source for OS/K's bootloader.
OS/K being intended to only run on x86-64 systems, we have not divided
this folder into one sub-folder per architecture.
-It is divided in two parts each of exactly 512 bytes:
- - mbr.s (and its auxiliary file mbr.inc)
- This is our Master Boot Record (MBR). It switches to long mode
- (64 bits mode) then loads the second half of the bootloader.
- The MBR must be placed precisely on the first sector of the hard drive.
+The bootloader itself is external to the OS/K project. We are using GRUB 2 to load
+our kernel loader in memory.
- - loader.s
- This is the Kernel Loader. It switches to long mode and makes stuff.
+The kernel loader, that we call the loader, is the main subject of this folder.
+This loader is intended to load the ELF64 kernel at the specified address and
+prepare it for the hard work it have to do :
+ - Parsing the ELF64
+ - Load the kernel
+ - Prepare a structure for it with memory map, cpu infos, and other devices infos.
diff --git a/boot/mbr/mbr.asm b/boot/mbr/mbr.asm
deleted file mode 100644
index 1a08f74..0000000
--- a/boot/mbr/mbr.asm
+++ /dev/null
@@ -1,191 +0,0 @@
-;=----------------------------------------------------------------------------=;
-; GNU GPL OS/K ;
-; ;
-; Desc: Bootsector for OS/K ;
-; (x86_64 architecture only) ;
-; ;
-; ;
-; 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 ;
-; 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 . ;
-;=----------------------------------------------------------------------------=;
-
-;; BOOT "SEGMENT"
-%define BOOT_SEG 0x07c0 ; (BOOT_SEG << 4) + BOOT_OFF = 0x007c00
-%define BOOT_OFF 0x0000
-
-;; STACK "SEGMENT"
-%define STACK_SEG 0x0600 ; (STACK_SEG << 4) + STACK_OFF = 0x007000
-%define STACK_OFF 0x1000
-
-;; DISK BUFFER "SEGMENT"
-%define BUFFER_SEG 0x2000 ; (BUFFER_SEG << 4) + BUFFER_OFF = 0x020000
-%define BUFFER_OFF 0x0000
-
-;; SECOND STAGE LOADER "SEGMENT"
-%define LOAD_SEG 0x0000 ; (LOAD_SEG << 4) + LOAD_OFF = 0x001000
-%define LOAD_OFF 0x1000
-
-[BITS 16] ; Ensure 16-bit code (because fuck UEFI)
-
-Intro:
-
- jmp short _start ; Jump over the BIOS PARAMETER BLOCK
- nop ; Required by BIOS to recognize the Disk loul
-BPB:
- ;---------------------------------------------------;
- ; Disk description table ;
- ;---------------------------------------------------;
- %define OEMName bp+0x03 ; Disk label
- %define bytesPerSector bp+0x0b ; Bytes per sector
- %define sectorsPerCluster bp+0x0d ; Sectors per cluster
- %define reservedSectors bp+0x0e ; Reserved sectors
- %define fats bp+0x10 ; Number of fats
- %define rootDirEntries bp+0x11 ; Number of entries in root dir
- %define sectors bp+0x13 ; Logical sectors
- %define mediaType bp+0x15 ; Media descriptor byte
- %define fatSectors bp+0x16 ; Sectors per FAT
- %define sectorsPerTrack bp+0x18 ; Sectors per track
- %define heads bp+0x1a ; Number of sides/heads
- %define hiddenSectors bp+0x1c ; Hidden sectors
- %define hugeSectors bp+0x20 ; LBA sectors
- %define biosBootdrvNum bp+0x24 ; Bootdrv number
- %define reserved bp+0x25 ; This is not used
- %define bootSignature bp+0x26 ; Bootdrv signature
- %define volumeId bp+0x27 ; Volume ID
- %define volumeLabel bp+0x2b ; Volume Label
- %define fatTypeLabel bp+0x36 ; File system type
-
- times 0x3b db 0x00 ; ALLOCATE THE SECTORS FOR THE BPB
-
-;; ENTRY POINT
-_start:
- jmp BOOT_SEG:$+5 ; Fix the cs:ip registers with a vaudou magical trip
-
-bootstrap:
- jmp go
-
-;; LOVELY DATA
-FileNotFound db "First Stage ERROR : NO LOADER", 0
-DiskError db "First Stage ERROR : DISK", 0
-UserData dw 0
-Bootdrv db 0
-filename db "LOADER BIN"
-
-
-;; GO !
-go:
- mov ax, BOOT_SEG ; Set segments to the location of the bootloader
- mov ds, ax
- mov es, ax
-
- ;; INIT STACK
- cli
- mov ax, STACK_SEG ; Init the stack
- mov ss, ax ; Continue init the stack
- mov sp, STACK_OFF ; Ok man, the stack is in 4K :O
- sti
- mov bp, (0x7c0-STACK_SEG) << 4 ; Correct bp (the disk description table)
-
- ;; INITIALIZE BOOT DISK
- or dl, dl ; Verifying dl points actually to the boot drive
- jz load_root
- mov byte [Bootdrv], dl ; Another soul (the disk) saved!
- mov ah, 0x08
- int 0x13 ; int 0x13 : read drive parameters/geom
- jc load_root
- and cx, 0x003f ; Maximum sector number is the high bits 6-7 of cl
- mov word [sectorsPerTrack], cx ; And whose low 8 bits are in ch
- mov dl, dh ; Convert the maximum head number to a word with another vaudou magical trip
- xor dh, dh
- inc dx ; because head numbers start at zero
- mov word [heads], dx ; Another soul (the heads number) saved!
-
-
- ;; LOAD THE ROOT DIRECTORY FROM DISK
-load_root:
- xor cx, cx
- mov ax, 32 ; Size of root dir = (rootDirEntries * 32) / bytesPerSector
- mul word [rootDirEntries] ; multiply by the total size of the root directory
- div word [bytesPerSector] ; divide by the number of bytes used per sector
- xchg cx, ax
-
- mov al, byte [fats] ; Location of root dir = (fats * fatSectors) + reservedSectors
- mul word [fatSectors] ; multiply by the sectors used
- add ax, word [reservedSectors] ; increase ax by the reserved sectors
- mov word [UserData], ax ; Start of user data = startOfRoot + numberOfRoot
- add word [UserData], cx ; Add the size and location of the root directory
-
- mov di, BUFFER_SEG ; Set the extra segment to the disk buffer
- mov es, di
- mov di, BUFFER_OFF ; Set es:di and load the root directory into the disk buffer
- call read_sectors ; Read the sectors
-
- ;; FIND THE SECOND STAGE LOADER
- mov di, BUFFER_OFF ; Set es:di to the disk buffer
- mov cx, word [rootDirEntries] ; Search through all of the root dir entries
- xor ax, ax ; Clear ax for the file entry offset
-
-search_root:
- xchg cx, dx ; Save cx because it's a loop counter
- mov si, filename ; Load the filename
- mov cx, 11 ; Compare first 11 bytes
- rep cmpsb ; Compare si and di cx times
- je load_fat ; We found the loader
- add ax, 32 ; File entry offset
- mov di, BUFFER_OFF ; Point back to the start of the entry
- add di, ax ; Add the offset to point to the next entry
- xchg dx, cx
- loop search_root ; Continue to search for the file
-
- ;; ERROR...
- mov si, FileNotFound ; Could not find the file
- call print
- call reboot
-
- ;; LOAD THE FAT FROM THE FILE
-load_fat:
- mov ax, word [es:di + 15] ; Get the file cluster at offset 26
- push ax ; Store the FAT cluster
- xor ax, ax ; Size of fat = (fats * fatSectors)
- mov al, byte [fats] ; Move number of fats into al
- mul word [fatSectors] ; Move fat sectors into bx
- mov cx, ax ; Store in cx
- mov ax, word [reservedSectors] ; Convert the first fat on the disk
- mov di, BUFFER_OFF ; Set es:di and load the fat sectors into the disk buffer
- call read_sectors ; Read the sectors
-
- ;; LOAD THE CLUSTERS OF THE LOADER AND JUMP
- mov di, LOAD_SEG
- mov es, di ; Set es:bx to where the file will load
- mov di, LOAD_OFF
- pop ax ; File cluster restored
- call read_clusters ; Read clusters from the file
- mov dl, byte [Bootdrv] ; Pass the boot Bootdrv into dl
- jmp LOAD_SEG:LOAD_OFF ; Jump to the file loaded!
-
- hlt ; This should never be hit...
- ; ...
- ; ...
- ; I hope....
- ; ...
- call reboot
-
-%include "boot/mbr/mbr.inc"
-
-;; END
- times 510 - ($ - $$) db 0 ; Pad remainder of boot sector with zeros
- dw 0xaa55 ; Boot signature
diff --git a/boot/mbr/mbr.inc b/boot/mbr/mbr.inc
deleted file mode 100644
index b006cce..0000000
--- a/boot/mbr/mbr.inc
+++ /dev/null
@@ -1,177 +0,0 @@
-;=----------------------------------------------------------------------------=;
-; GNU GPL OS/K ;
-; ;
-; Desc: Bootsector for OS/K INCLUDED FUNCTIONS ;
-; (x86_64 architecture only) ;
-; ;
-; ;
-; 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 ;
-; 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 . ;
-;=----------------------------------------------------------------------------=;
-
-[BITS 16]
-
-read_clusters:
-;---------------------------------------------------;
-; Read file clusters, starting at the given cluster,;
-; expects FAT to be loaded into the disk buffer. ;
-; Please note that this may allocate up to 128KB ;
-; of ram. ;
-; ;
-; Expects: AX = Starting cluster ;
-; ES:DI = Location to load clusters ;
-; ;
-; Returns: None ;
-; ;
-;---------------------------------------------------;
- pusha
- push es
- .cluster_loop:
- xor bh, bh
- xor dx, dx
- push ax ; Get the cluster start = (cluster - 2) * sectorsPerCluster + UserData
- sub ax, 2 ; Subtract 2
- mov bl, byte [sectorsPerCluster] ; Sectors per cluster is a byte value
- mul bx ; multiply (cluster - 2) * sectorsPerCluster
- add ax, word [UserData] ; add the UserData
- xor ch, ch
- mov cl, byte [sectorsPerCluster] ; Sectors to read
- call read_sectors ; Read the sectors
- pop ax ; Current cluster number
- xor dx, dx
- ;; Calculate next sector for FAT16 (cluster * 2)
- mov bx, 2 ; Multiply the cluster by two (cluster is in ax)
- mul bx
- ;; Load sector in RAM
- push ds
- push si
- mov si, BUFFER_SEG
- mov ds, si ; Temporarly set ds:si to the FAT buffer
- mov si, BUFFER_OFF
- add si, ax ; Point to the next cluster in the FAT entry
- mov ax, word [ds:si] ; Load ax to the next cluster in FAT
- pop si
- pop ds
- ;; Next
- cmp ax, 0xfff8 ; Check if we are at the end of the file?
- jae .done
- add di, 512 ; Add to the pointer offset
- jnc .cluster_loop
- ;; Correct the buffer because an error will occur if the buffer in memory
- mov dx, es ; overlaps a 64k page boundry, when di overflows
- add dh, 0x10 ; it will trigger the carry flag, so correct
- mov es, dx ; extra segment by 0x1000
- jmp .cluster_loop ; Load the next file cluster
- .done:
- pop es
- popa
- ret
-
-
-read_sectors:
-;---------------------------------------------------;
-; Read sectors starting at a given sector by ;
-; the given times and load into a buffer. Please ;
-; note that this may allocate up to 128KB of ram. ;
-; ;
-; Expects: AX = Starting sector ;
-; CX = Number of sectors to read ;
-; ES:DI = Location to load sectors ;
-; ;
-; Returns: None ;
-; ;
-;---------------------------------------------------;
- pusha
- push es
- mov bx, di ; Convert es:di to es:bx for int 13h
- .sector_loop:
- push ax
- push cx
- xor dx, dx
- div word [sectorsPerTrack] ; Divide the lba (value in ax) by sectorsPerTrack
- mov cx, dx ; Save the absolute sector value
- inc cx
- xor dx, dx ; Divide by the number of heads
- div word [heads] ; to get absolute head and track values
- mov dh, dl ; Move the absolute head into dh
- mov ch, al ; Low 8 bits of absolute track
- shl ah, 1 ; High 2 bits of absolute track
- shl ah, 1
- shl ah, 1
- shl ah, 1
- shl ah, 1
- shl ah, 1
- or cl, ah ; Now cx is set with respective track and sector numbers
- mov dl, byte [Bootdrv] ; Set correct Bootdrv for int 13h
- mov di, 21 ; Try five times to read the sector because I love 21
- .attempt_read:
- mov ax, 0x0201 ; Read Sectors func of int 13h, read one sector
- int 0x13 ; Call int 13h (BIOS disk I/O)
- jnc .read_ok ; If no carry set, the sector has been read
- xor ah, ah ; Reset Bootdrv func of int 13h
- int 0x13 ; Call int 13h (BIOS disk I/O)
- dec di ; Decrease read attempt counter
- jnz .attempt_read ; Try to read the sector again
- mov si, DiskError ; Error reading the disk :/
- call print
- jmp reboot
- .read_ok:
- pop cx
- pop ax
- inc ax ; Increase the next sector to read
- add bx, word [bytesPerSector] ; Add to the buffer address for the next sector
- jnc .next_sector
- ;; Fixing buffer because an error will occur if the buffer in memory
- mov dx, es ; overlaps a 64k page boundry, when bx overflows
- add dh, 0x10 ; it will trigger the carry flag, so correct
- mov es, dx ; es segment by 0x1000
- .next_sector:
- loop .sector_loop
- pop es
- popa
- ret
-
-print:
-;---------------------------------------------------;
-; Print out a simple string. ;
-; ;
-; Expects: DS:SI = String to print ;
-; ;
-; Returns: None ;
-; ;
-;---------------------------------------------------;
- lodsb ; Load byte from ds:si to al
- or al, al ; If al is empty stop looping
- jz .done ; Done looping and return
- mov ah, 0x0e ; Teletype output
- int 0x10 ; Video interupt
- jmp print ; Loop untill string is null
- .done:
- ret
-
-reboot:
- xor ax, ax
- int 0x16 ; Get a single keypress
- mov ah, 0x0e ; Teletype output
- mov al, 0x0d ; Carriage return
- int 0x10 ; Video interupt
- mov al, 0x0a ; Line feed
- int 0x10 ; Video interupt
- mov al, 0x0a ; Line feed
- int 0x10 ; Video interupt
- xor ax, ax
- int 0x19 ; Reboot the system