Merge pull request #17 from E-Almqvist/dev

Kernel!

.gitignore

@@ -1,2 +1,3 @@
 bin/
 *.bin
+*.o

compile.sh

@@ -1,6 +1,16 @@
 #!/usr/bin/bash
 
+done="[OK]"
+fail="[FAIL]"
+
 srcDir=src
 binDir=bin
 
-nasm -f bin $srcDir/bootloader.asm -i $srcDir -o $binDir/bootloader.bin
+echo -n "Compiling bootloader... "
+nasm -f bin $srcDir/bootloader.asm -i $srcDir -o $binDir/bootloader.bin && echo $done
+
+echo -n "Compiling kernel... "
+gcc -ffreestanding -c $srcDir/kernel.c -o $binDir/kernel.o && ld -o $binDir/kernel.bin -Ttext 0x1000 $binDir/kernel.o --oformat binary 2>/dev/null && echo $done
+
+echo -n "Creating kernel image... "
+cat $binDir/bootloader.bin $binDir/kernel.bin > $binDir/os-image && echo $done

src/bootloader.asm

@@ -1,12 +1,21 @@
 [org 0x7c00] ; bootsector
+	KERNEL_OFFSET equ 0x1000
+
 	; Save the boot drive index
 	mov [BOOT_DRIVE], dl
 
 	; Move the stack pointer somewhere safe
-	mov bp, 0x8000 ; move it to 0x8000
+	mov bp, 0x9000 ; move it to 0x8000
 	mov sp, bp
 
+	; Load kernel into memory
+	mov bx, stat_kernel_load
+	call println
+	call load_kernel
+
 	; Switching to PM
+	mov bx, stat_pm_init
+	call println
 	call pm_preinit
 
 	jmp $  ; inf loop
@@ -16,12 +25,25 @@
 %include "pm.asm"
 
 BEGIN_PM:
-	mov ebx, welcome_string
+	mov ebx, stat_pm_init 
 	call vga_print
 
 	jmp $
 
-welcome_string:	db "e Operating-System (eOS): Version 2021 0.0", ASCII_END
+[bits 16]
+
+load_kernel:
+	mov bx, KERNEL_OFFSET	; Load kernel at the kernel offset
+	mov dh, 15		; Read 15 sectors
+	mov dl, [BOOT_DRIVE]	; Drive index
+	call disk_read		; Load the kernel
+
+	ret
+
+stat_pm_init:		db "Entering 32bit Protected Mode...", ASCII_END
+stat_kernel_load:	db "Loading kernel into memory...", ASCII_END
+stat_boot_success:	db "Booting complete!", ASCII_END
+
 BOOT_DRIVE: db 0
 
 ; Bootsector

src/kernel.c

@@ -0,0 +1,7 @@
+// VGA base address: 0xb8000
+// Charpos = 0xb8000 + 2(row*80 + col)
+
+void main() {
+	char* video_mem = (char*)0xb8000; // VGA Video Memory location
+	*video_mem = 'X'; 
+}

src/pm/gdt.asm

@@ -34,8 +34,8 @@ gdt_end:		; Mark the end so we can get the delta-memory (size of GDT)
 
 ; GDT descriptor
 gdt_descriptor:
-	dw gdt_end - gdt_start - 1	; Size of GDT is always -1 of actual size (WHY?!?!?!?!??!)
-	dd gdt_start			; Pointer to the GDT
+	dw gdt_end - gdt_start - 1	; GDT size 
+	dd gdt_start			; GDT pointer
 
 
 ; Lazy constants