update makefile

Author: salvoronis

Makefile

@@ -1,19 +1,23 @@
 CC = gcc
 ASM = nasm
+LD = ld
 
 all: os-image
 
 run: all
-	qemu-system-x86_64 os-image
+	qemu-system-x86_64 -fda os-image
 
 kernel.o: kernel.c
-	$(CC) -ffreestanding -c $< -o $@
+	$(CC) -fno-pie -m32 -ffreestanding -c $< -o $@
+
+kernel_entry.o: kernel_entry.asm
+	$(ASM) $< -f elf -o $@
 
 bootstrap.bin: bootstrap.asm
 	$(ASM) $< -f bin -o $@
 
-kernel.bin: kernel.o
-	$(LD) -o $@ -Ttext 0x1000 $^ --oformat binary
+kernel.bin: kernel_entry.o kernel.o
+	$(LD) -m elf_i386 -o $@ -Ttext 0x1000 $^ --oformat binary
 
 os-image: bootstrap.bin kernel.bin
 	cat $^ > $@

b

@@ -0,0 +1,2 @@
+floppya: 1_44=os-image , status=inserted
+boot: a

bootstrap.asm

@@ -1,4 +1,4 @@
-[org 0x7C00]
+org 0x7C00
 
 KERNEL_OFFSET equ 0x1000 ; offset to reach main func in kernel.c
 
@@ -29,20 +29,18 @@ load_kernel:
 	call print_string
 
 	mov bx, KERNEL_OFFSET ; destination
-	mov dh, 6 ; 6 sectors of drive
+	mov dh, 2 ; 2 sectors of drive
 	mov dl, [BOOT_DRIVE]
 	call disk_load
 
 	ret
 
 [bits 32]
-;extern main
 
 BEGIN_PM:
 	mov ebx, MSG_PROT_MODE
 	call print_string_pm
 
-	;call main
 	jmp KERNEL_OFFSET
 
 	jmp $

gdt.asm

@@ -8,7 +8,7 @@ gdt_code:
 	; 1st flags: (present)1 (privilege)00 (descr type)1 -> 1001b
 	; type flags: (code)1 (conforming)0 (readable)1 (accessed)0 -> 1010b
 	; 2nd flags: (granularity)1 (32-bit default)1 (64-bit seg)0 (AVL)0 -> 1100b
-	dw 0xfffff	; Limit 0-15
+	dw 0xffff	; Limit 0-15
 	dw 0x0		; Base 0-15
 	db 0x0		; Base 16-23
 	db 10011010b	; 1st flag, type flag
@@ -17,7 +17,7 @@ gdt_code:
 
 gdt_data:
 	;type flags: (code)0 (expand down)0 (writable)1 (accessed)0 -> 0010b
-	dw 0xfffff
+	dw 0xffff
 	dw 0x0
 	dw 0x0
 	db 10010010b

kernel.c

@@ -1,4 +1,4 @@
-void main() {
-	char* video_memory = (char*) 0xB8000;
+void kernel() {
+	char* video_memory = (char*) 0xb8000;
 	*video_memory = 'X';
 }

kernel_entry.asm

@@ -0,0 +1,4 @@
+[bits 32]
+[extern kernel]
+call kernel
+jmp $

switch_to_32.asm

@@ -8,16 +8,19 @@ switch_to_32:
 	or eax, 0x1
 	mov cr0, eax
 
-	jmp init_pm
+	jmp CODE_SEG:init_pm
 
 [bits 32]
 init_pm:
-	mov ax, DATA_SEG
-	mov ds, ax
-	mov ss, ax
-	mov es, ax
-	mov fs, ax
-	mov gs, ax
+	;inc eax
+	;jmp $
+	mov ecx, DATA_SEG
+;jmp $
+	mov ds, ecx
+	mov ss, ecx
+	mov es, ecx
+	mov fs, ecx
+	mov gs, ecx
 
 	mov ebp, 0x90000
 	mov esp, ebp