separate kernel and bootloader

Makefile

@@ -1,5 +1,14 @@
-all:
+FILES = ./build/kernel.asm.o
+
+all: ./bin/boot.bin $(FILES)
+	rm -rf ./bin/os.bin
+	dd if=./bin/boot.bin >> ./bin/os.bin
+
+./bin/boot.bin: ./src/boot/boot.asm
 	nasm -f bin ./src/boot/boot.asm -o ./bin/boot.bin
 
+./build/kernel.asm.o: ./src/kernel.asm
+	nasm -f elf -g ./src/kernel.asm -o ./build/kernel.asm.o
+
 clean:
 	rm -rf ./bin/boot.bin

build.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+export PREFIX="$HOME/opt/cross"
+export TARGET=i686-elf
+export PATH="$PREFIX/bin:$PATH"
+make all

src/boot/boot.asm

@@ -29,8 +29,8 @@ step2:
     mov eax, cr0
     or eax, 0x1
     mov cr0, eax
-    jmp CODE_SEG:load32
-
+    ;jmp CODE_SEG:load32
+    jmp $
 
 ; -- GDT --
 gdt_start:
@@ -58,33 +58,5 @@ gdt_descriptor:
     dw gdt_end - gdt_start-1
     dd gdt_start
 
-;
-; ---- protected mode starts here ----
-;
-[BITS 32]
-load32:
-    ; set data segments to the correct GDT
-    mov ax, DATA_SEG
-    mov ds, ax
-    mov es, ax
-    mov fs, ax
-    mov gs, ax
-    mov ss, ax
-
-    ; move the stack furthet
-    mov ebp, 0x00200000
-    mov esp, ebp
-
-    ; enable the A20 line
-    in al, 0x92
-    test al, 2
-    jnz .after
-    or al, 2
-    and al, 0xFE
-    out 0x92, al
-.after:
-
-    jmp $
-
 times 510- ($ - $$) db 0 ; zero out 510 bytes of data
 dw 0xAA55                ; add boot signature

src/kernel.asm

@@ -0,0 +1,27 @@
+[BITS 32]
+CODE_SEG equ 0x08
+DATA_SEG equ 0x10
+
+load32:
+    ; set data segments to the correct GDT
+    mov ax, DATA_SEG
+    mov ds, ax
+    mov es, ax
+    mov fs, ax
+    mov gs, ax
+    mov ss, ax
+
+    ; move the stack furthet
+    mov ebp, 0x00200000
+    mov esp, ebp
+
+    ; enable the A20 line
+    in al, 0x92
+    test al, 2
+    jnz .after
+    or al, 2
+    and al, 0xFE
+    out 0x92, al
+    .after:
+
+    jmp $

src/linker.ld

@@ -0,0 +1,27 @@
+ENTRY(_start)
+OUTPUT_FORMAT(binary)
+SECTIONS
+{
+    . = 1M
+    .text :
+    {
+        *(.text)
+    }
+
+    .rodata :
+    {
+        *(.rodata)
+    }
+
+    .data :
+    {
+        *(.data)
+    }
+
+    .bss :
+    {
+        *(COMMON)
+        *(.bss)
+    }
+}
+