copy gdt to kernel

Makefile

@@ -1,24 +1,28 @@
-ENTRYPOINT		= 0x10000
-
-ASM				= nasm
-LD				= ld
-ASMBFLAGS		= -I boot/include/
-ASMKFLAGS		= -I include/ -f elf
-LDFLAGS			= -m elf_i386 -s -Ttext $(ENTRYPOINT)
-ORANGESBOOT		= boot/boot.bin boot/loader.bin
-ORANGESKERNEL	= kernel.bin
-OBJS			= kernel/kernel.o
-BOOT_BIN		= boot/boot.bin
-LDR_BIN			= boot/loader.bin
-KERNEL_BIN		= kernel.bin
-
-IMG:=boot.img
-FLOPPY:=/mnt/floppy/
+ENTRYPOINT  = 0x10000
+
+ASM             = nasm
+CC              = gcc
+CFLAGS          = -m32 -g -I include/ -c -fno-builtin -fno-stack-protector
+LD              = ld
+ASMBFLAGS       = -I boot/include/
+ASMKFLAGS       = -I lib -f elf
+LDFLAGS         = -m elf_i386 -s -Ttext $(ENTRYPOINT)
+
+ORANGESBOOT     = boot/boot.bin boot/loader.bin
+ORANGESKERNEL   = kernel.bin
+OBJS            = kernel/kernel.o kernel/start.o lib/string.o
+BOOT_BIN        = boot/boot.bin
+LDR_BIN         = boot/loader.bin
+KERNEL_BIN      = kernel.bin
+
+IMG             = boot.img
+FLOPPY          = /mnt/floppy/
 
 .PHONY : clean everything imgage all
 
 everything: clean $(ORANGESBOOT) $(ORANGESKERNEL)
-all: everything imgage
+all: everything image
+bochs: all bochstart
 
 image : $(LDR_BIN) $(KERNEL_BIN)
 	# bximg
@@ -28,14 +32,17 @@ image : $(LDR_BIN) $(KERNEL_BIN)
 	sudo cp $(KERNEL_BIN) $(FLOPPY) -fv
 	sudo umount $(FLOPPY)
 
+bochstart:
+	bochs -f bochsrc.bxrc
+
 clean :
 	rm -f $(OBJS) $(ORANGESBOOT) $(ORANGESKERNEL)
 
 $(BOOT_BIN) : boot/boot.asm boot/include/lib.asm boot/include/fat12hdr.asm
 	$(ASM) $(ASMBFLAGS) -o $@ $<
 
 $(LDR_BIN) : boot/loader.asm boot/include/lib.asm \
-			boot/include/fat12hdr.asm boot/include/pm.asm
+             boot/include/fat12hdr.asm boot/include/pm.asm
 	$(ASM) $(ASMBFLAGS) -o $@ $<
 
 $(ORANGESKERNEL) : $(OBJS)
@@ -44,11 +51,8 @@ $(ORANGESKERNEL) : $(OBJS)
 kernel/kernel.o : kernel/kernel.asm
 	$(ASM) $(ASMKFLAGS) -o $@ $<
 
-kernel/start.o : kernel/start.c include/type.h include/const.h include/protect.h
+kernel/start.o : kernel/start.c kernel/start.h
 	$(CC) $(CFLAGS) -o $@ $<
 
-lib/kliba.o : lib/kliba.asm
-	$(ASM) $(ASMKFLAGS) -o $@ $<
-
 lib/string.o : lib/string.asm
 	$(ASM) $(ASMKFLAGS) -o $@ $<

kernel/kernel.asm

@@ -1,37 +1,27 @@
-[section .data]
-randstr	db "Welcome to kernel by techlog.cn", 0
+SELECTOR_KERNEL_CS	equ	8
+
+; 导入函数与全局变量
+extern  copy_gdt	
+extern	gdt_ptr
+
+[SECTION .bss]
+StackSpace		resb	2 * 1024 * 1024
+StackTop:
 
 [section .text]
 global _start
 
 _start:
-	push dword randstr
-	call DispStr
-	add esp, 4
-	jmp	$
-
-DispStr:
-	push	ebp
-	mov	ebp, esp
-	push	ebx
-	push	esi
-	push	edi
-
-	mov	esi, [ebp + 8]	; pszInfo
-	mov	edi, (80 * 7) * 2
-	mov	ah, 0Fh
-.1:
-	lodsb
-	test	al, al
-	jz	.2
-.3:
-	mov	[gs:edi], ax
-	add	edi, 2
-	jmp	.1
-
-.2:
-	pop	edi
-	pop	esi
-	pop	ebx
-	pop	ebp
-	ret
+	mov	esp, StackTop	; 堆栈在 bss 段中
+
+	sgdt	[gdt_ptr]	; cstart() 中将会用到 gdt_ptr
+	call	copy_gdt	; 在此函数中改变了gdt_ptr，让它指向新的GDT
+	lgdt	[gdt_ptr]	; 使用新的GDT
+
+	jmp	SELECTOR_KERNEL_CS:csinit
+csinit:                 ; 长跳转，让 GDT 切换生效
+
+	push	0
+	popfd
+
+	hlt