Entering unreal mode

Makefile

@@ -5,8 +5,7 @@
 all: boot.bin
 
 clean:
-	rm -f *.o
-	rm -f boot.elf boot.bin
+	rm -f *.o boot.elf boot.bin
 
 config.mk: | config.default.mk
 	cp config.default.mk $@
@@ -14,8 +13,8 @@ config.mk: | config.default.mk
 boot.bin: boot.elf
 	objcopy -O binary --only-section=.text boot.elf $@
 
-boot.elf: boot16.o fernlader.ld
-	$(LD) $(LDFLAGS) -o $@ boot16.o
+boot.elf: lboot.o fernlader.ld
+	$(LD) $(LDFLAGS) -o $@ lboot.o
 
 .S.o:
 	$(CC) $(CFLAGS) -c -o $@ $(@:.o=.S)

lboot.S

@@ -7,21 +7,23 @@
 _start:     cli
             cld
 
-            mov         %cs, %ax
+            // we keep our text and data close to each other
+            xor         %ax, %ax
             mov         %ax, %ds
 
-            mov         $message, %si
+            mov         $msg_start, %si
             call        print
 
+            mov         $msg_a20, %si
+            call        print
             call        enable_a20
 
-            lea         message, %si
+            mov         $msg_unreal, %si
             call        print
+            call        unreal
 
-            lgdt        gdt_ptr
-
-            call        enter_prot
-
+            mov         $msg_fin, %si
+            call        print
 1:          hlt
             jmp         1b
 
@@ -31,9 +33,22 @@ enable_a20: // TODO more thorough implementation
             outb        %al, $0x92
             ret
 
-enter_prot: mov         %cr0, %eax
-            or          $1, %al
+unreal:     push        %ds
+            lgdt        gdt_ptr
+
+            mov         %cr0, %eax
+            or          $0x01, %al
             mov         %eax, %cr0
+            ljmp        $0x8, $1f
+
+1:          mov         $0x10, %cx
+            mov         %cx, %ds
+            
+            and         $0xFE, %al
+            mov         %eax, %cr0
+            ljmp        $0x0, $2f
+
+2:          pop         %ds
             ret
 
 print:      xor         %bx, %bx
@@ -72,4 +87,7 @@ gdt:        // entry 0: null descriptor
 gdt_ptr:    .word       gdt_size-1
             .long       gdt
 
-message:    .asciz     "Hello, World!\r\n"
+msg_start:  .asciz      "Netboot via fernlader v1 ...\r\n"
+msg_a20:    .asciz      " * Enabling A20\r\n"
+msg_unreal: .asciz      " * Unreal Mode\r\n"
+msg_fin:    .asciz      "Finished.\r\n"