lesson 14

14-checkpoint/boot/32bit_print.asm

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+../../08-32bit-print/32bit-print.asm

14-checkpoint/boot/bootsect.asm

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+; Identical to lesson 13's boot sector, but the %included files have new paths
+[org 0x7c00]
+KERNEL_OFFSET equ 0x1000 ; The same one we used when linking the kernel
+
+    mov [BOOT_DRIVE], dl ; Remember that the BIOS sets us the boot drive in 'dl' on boot
+    mov bp, 0x9000
+    mov sp, bp
+
+    mov bx, MSG_REAL_MODE 
+    call print
+    call print_nl
+
+    call load_kernel ; read the kernel from disk
+    call switch_to_pm ; disable interrupts, load GDT,  etc. Finally jumps to 'BEGIN_PM'
+    jmp $ ; Never executed
+
+%include "boot/print.asm"
+%include "boot/print_hex.asm"
+%include "boot/disk.asm"
+%include "boot/gdt.asm"
+%include "boot/32bit_print.asm"
+%include "boot/switch_pm.asm"
+
+[bits 16]
+load_kernel:
+    mov bx, MSG_LOAD_KERNEL
+    call print
+    call print_nl
+
+    mov bx, KERNEL_OFFSET ; Read from disk and store in 0x1000
+    mov dh, 2
+    mov dl, [BOOT_DRIVE]
+    call disk_load
+    ret
+
+[bits 32]
+BEGIN_PM:
+    mov ebx, MSG_PROT_MODE
+    call print_string_pm
+    call KERNEL_OFFSET ; Give control to the kernel
+    jmp $ ; Stay here when the kernel returns control to us (if ever)
+
+
+BOOT_DRIVE db 0 ; It is a good idea to store it in memory because 'dl' may get overwritten
+MSG_REAL_MODE db "Started in 16-bit Real Mode", 0
+MSG_PROT_MODE db "Landed in 32-bit Protected Mode", 0
+MSG_LOAD_KERNEL db "Loading kernel into memory", 0
+
+; padding
+times 510 - ($-$$) db 0
+dw 0xaa55

14-checkpoint/boot/disk.asm

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+../../07-bootsector-disk/boot_sect_disk.asm

14-checkpoint/boot/gdt.asm

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+../../09-32bit-gdt/32bit-gdt.asm

14-checkpoint/boot/kernel_entry.asm

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+../../13-kernel-barebones/kernel_entry.asm

14-checkpoint/boot/switch_pm.asm

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+../../10-32bit-enter/32bit-switch.asm