从boot引导到loader引导完整运行

此文针对该文章对loader引导进行了完善后的完整运行过程。（具体细节请参见下文）

boot引导升级，成功引导运行loader_What’smean的博客-CSDN博客boot引导升级，成功引导运行loaderhttps://blog.csdn.net/weixin_42492218/article/details/127751460?spm=1001.2014.3001.5501

loader.asm完整代码

（无注释）：

注释详解请看：完整的loader引导代码详解_What’smean的博客-CSDN博客

org	10000h
	jmp	Label_Start
 
%include	"fat12.inc"
 
BaseOfKernelFile	equ	0x00
OffsetOfKernelFile	equ	0x100000
 
BaseTmpOfKernelAddr	equ	0x00
OffsetTmpOfKernelFile	equ	0x7E00
 
MemoryStructBufferAddr	equ	0x7E00
 
[SECTION gdt]
 
LABEL_GDT:		dd	0,0
LABEL_DESC_CODE32:	dd	0x0000FFFF,0x00CF9A00
LABEL_DESC_DATA32:	dd	0x0000FFFF,0x00CF9200
 
GdtLen	equ	$ - LABEL_GDT
GdtPtr	dw	GdtLen - 1
	dd	LABEL_GDT
 
SelectorCode32	equ	LABEL_DESC_CODE32 - LABEL_GDT
SelectorData32	equ	LABEL_DESC_DATA32 - LABEL_GDT
 
[SECTION gdt64]
 
LABEL_GDT64:		dq	0x0000000000000000
LABEL_DESC_CODE64:	dq	0x0020980000000000
LABEL_DESC_DATA64:	dq	0x0000920000000000
 
GdtLen64	equ	$ - LABEL_GDT64
GdtPtr64	dw	GdtLen64 - 1
		dd	LABEL_GDT64
 
SelectorCode64	equ	LABEL_DESC_CODE64 - LABEL_GDT64
SelectorData64	equ	LABEL_DESC_DATA64 - LABEL_GDT64
 
[SECTION .s16]
[BITS 16]
 
Label_Start:
 
	mov	ax,	cs
	mov	ds,	ax
	mov	es,	ax
	mov	ax,	0x00
	mov	ss,	ax
	mov	sp,	0x7c00
 
;=======	display on screen : Start Loader......
 
	mov	ax,	1301h
	mov	bx,	000fh
	mov	dx,	0200h		;row 2
	mov	cx,	12
	push	ax
	mov	ax,	ds
	mov	es,	ax
	pop	ax
	mov	bp,	StartLoaderMessage
	int	10h
 
;=======	open address A20
	push	ax
	in	al,	92h
	or	al,	00000010b
	out	92h,	al
	pop	ax
 
	cli
 
	db	0x66
	lgdt	[GdtPtr]	
 
	mov	eax,	cr0
	or	eax,	1
	mov	cr0,	eax
 
	mov	ax,	SelectorData32
	mov	fs,	ax
	mov	eax,	cr0
	and	al,	11111110b
	mov	cr0,	eax
 
	sti
 
;=======	reset floppy
 
	xor	ah,	ah
	xor	dl,	dl
	int	13h
 
;=======	search kernel.bin
	mov	word	[SectorNo],	SectorNumOfRootDirStart
 
Lable_Search_In_Root_Dir_Begin:
 
	cmp	word	[RootDirSizeForLoop],	0
	jz	Label_No_LoaderBin
	dec	word	[RootDirSizeForLoop]	
	mov	ax,	00h
	mov	es,	ax
	mov	bx,	8000h
	mov	ax,	[SectorNo]
	mov	cl,	1
	call	Func_ReadOneSector
	mov	si,	KernelFileName
	mov	di,	8000h
	cld
	mov	dx,	10h
	
Label_Search_For_LoaderBin:
 
	cmp	dx,	0
	jz	Label_Goto_Next_Sector_In_Root_Dir
	dec	dx
	mov	cx,	11
 
Label_Cmp_FileName:
 
	cmp	cx,	0
	jz	Label_FileName_Found
	dec	cx
	lodsb	
	cmp	al,	byte	[es:di]
	jz	Label_Go_On
	jmp	Label_Different
 
Label_Go_On:
	
	inc	di
	jmp	Label_Cmp_FileName
 
Label_Different:
 
	and	di,	0FFE0h
	add	di,	20h
	mov	si,	KernelFileName
	jmp	Label_Search_For_LoaderBin
 
Label_Goto_Next_Sector_In_Root_Dir:
	
	add	word	[SectorNo],	1
	jmp	Lable_Search_In_Root_Dir_Begin
	
;=======	display on screen : ERROR:No KERNEL Found
 
Label_No_LoaderBin:
 
	mov	ax,	1301h
	mov	bx,	008Ch
	mov	dx,	0300h		;row 3
	mov	cx,	21
	push	ax
	mov	ax,	ds
	mov	es,	ax
	pop	ax
	mov	bp,	NoLoaderMessage
	int	10h
	jmp	$
 
;=======	found loader.bin name in root director struct
 
Label_FileName_Found:
	mov	ax,	RootDirSectors
	and	di,	0FFE0h
	add	di,	01Ah
	mov	cx,	word	[es:di]
	push	cx
	add	cx,	ax
	add	cx,	SectorBalance
	mov	eax,	BaseTmpOfKernelAddr	;BaseOfKernelFile
	mov	es,	eax
	mov	bx,	OffsetTmpOfKernelFile	;OffsetOfKernelFile
	mov	ax,	cx
 
Label_Go_On_Loading_File:
	push	ax
	push	bx
	mov	ah,	0Eh
	mov	al,	'.'
	mov	bl,	0Fh
	int	10h
	pop	bx
	pop	ax
 
	mov	cl,	1
	call	Func_ReadOneSector
	pop	ax
 
;;;;;;;;;;;;;;;;;;;;;;;	
	push	cx
	push	eax
	push	fs
	push	edi
	push	ds
	push	esi
 
	mov	cx,	200h
	mov	ax,	BaseOfKernelFile
	mov	fs,	ax
	mov	edi,	dword	[OffsetOfKernelFileCount]
 
	mov	ax,	BaseTmpOfKernelAddr
	mov	ds,	ax
	mov	esi,	OffsetTmpOfKernelFile
 
Label_Mov_Kernel:	;------------------
	
	mov	al,	byte	[ds:esi]
	mov	byte	[fs:edi],	al
 
	inc	esi
	inc	edi
 
	loop	Label_Mov_Kernel
 
	mov	eax,	0x1000
	mov	ds,	eax
 
	mov	dword	[OffsetOfKernelFileCount],	edi
 
	pop	esi
	pop	ds
	pop	edi
	pop	fs
	pop	eax
	pop	cx
;;;;;;;;;;;;;;;;;;;;;;;	
 
	call	Func_GetFATEntry
	cmp	ax,	0FFFh
	jz	Label_File_Loaded
	push	ax
	mov	dx,	RootDirSectors
	add	ax,	dx
	add	ax,	SectorBalance
 
	jmp	Label_Go_On_Loading_File
 
Label_File_Loaded:
		
	mov	ax, 0B800h
	mov	gs, ax
	mov	ah, 0Fh				; 0000: 黑底    1111: 白字
	mov	al, 'G'
	mov	[gs:((80 * 0 + 39) * 2)], ax	; 屏幕第 0 行, 第 39 列。
 
KillMotor:
	
	push	dx
	mov	dx,	03F2h
	mov	al,	0	
	out	dx,	al
	pop	dx
 
;=======	get memory address size type
 
	mov	ax,	1301h
	mov	bx,	000Fh
	mov	dx,	0400h		;row 4
	mov	cx,	24
	push	ax
	mov	ax,	ds
	mov	es,	ax
	pop	ax
	mov	bp,	StartGetMemStructMessage
	int	10h
 
	mov	ebx,	0
	mov	ax,	0x00
	mov	es,	ax
	mov	di,	MemoryStructBufferAddr	
 
Label_Get_Mem_Struct:
 
	mov	eax,	0x0E820
	mov	ecx,	20
	mov	edx,	0x534D4150
	int	15h
	jc	Label_Get_Mem_Fail
	add	di,	20
 
	cmp	ebx,	0
	jne	Label_Get_Mem_Struct
	jmp	Label_Get_Mem_OK
 
Label_Get_Mem_Fail:
 
	mov	ax,	1301h
	mov	bx,	008Ch
	mov	dx,	0500h		;row 5
	mov	cx,	23
	push	ax
	mov	ax,	ds
	mov	es,	ax
	pop	ax
	mov	bp,	GetMemStructErrMessage
	int	10h
	jmp	$
 
Label_Get_Mem_OK:
	
	mov	ax,	1301h
	mov	bx,	000Fh
	mov	dx,	0600h		;row 6
	mov	cx,	29
	push	ax
	mov	ax,	ds
	mov	es,	ax
	pop	ax
	mov	bp,	GetMemStructOKMessage
	int	10h	
 
;=======	get SVGA information
 
	mov	ax,	1301h
	mov	bx,	000Fh
	mov	dx,	0800h		;row 8
	mov	cx,	23
	push	ax
	mov	ax,	ds
	mov	es,	ax
	pop	ax
	mov	bp,	StartGetSVGAVBEInfoMessage
	int	10h
 
	mov	ax,	0x00
	mov	es,	ax
	mov	di,	0x8000
	mov	ax,	4F00h
 
	int	10h
 
	cmp	ax,	004Fh
 
	jz	.KO
	
;=======	Fail
 
	mov	ax,	1301h
	mov	bx,	008Ch
	mov	dx,	0900h		;row 9
	mov	cx,	23
	push	ax
	mov	ax,	ds
	mov	es,	ax
	pop	ax
	mov	bp,	GetSVGAVBEInfoErrMessage
	int	10h
 
	jmp	$
 
.KO:
 
	mov	ax,	1301h
	mov	bx,	000Fh
	mov	dx,	0A00h		;row 10
	mov	cx,	29
	push	ax
	mov	ax,	ds
	mov	es,	ax
	pop	ax
	mov	bp,	GetSVGAVBEInfoOKMessage
	int	10h
 
;=======	Get SVGA Mode Info
 
	mov	ax,	1301h
	mov	bx,	000Fh
	mov	dx,	0C00h		;row 12
	mov	cx,	24
	push	ax
	mov	ax,	ds
	mov	es,	ax
	pop	ax
	mov	bp,	StartGetSVGAModeInfoMessage
	int	10h
 
 
	mov	ax,	0x00
	mov	es,	ax
	mov	si,	0x800e
 
	mov	esi,	dword	[es:si]
	mov	edi,	0x8200
 
Label_SVGA_Mode_Info_Get:
 
	mov	cx,	word	[es:esi]
 
;=======	display SVGA mode information
 
	push	ax
	
	mov	ax,	00h
	mov	al,	ch
	call	Label_DispAL
 
	mov	ax,	00h
	mov	al,	cl	
	call	Label_DispAL
	
	pop	ax
 
;=======
	
	cmp	cx,	0FFFFh
	jz	Label_SVGA_Mode_Info_Finish
 
	mov	ax,	4F01h
	int	10h
 
	cmp	ax,	004Fh
 
	jnz	Label_SVGA_Mode_Info_FAIL	
 
	add	esi,	2
	add	edi,	0x100
 
	jmp	Label_SVGA_Mode_Info_Get
		
Label_SVGA_Mode_Info_FAIL:
 
	mov	ax,	1301h
	mov	bx,	008Ch
	mov	dx,	0D00h		;row 13
	mov	cx,	24
	push	ax
	mov	ax,	ds
	mov	es,	ax
	pop	ax
	mov	bp,	GetSVGAModeInfoErrMessage
	int	10h
 
Label_SET_SVGA_Mode_VESA_VBE_FAIL:
 
	jmp	$
 
Label_SVGA_Mode_Info_Finish:
 
	mov	ax,	1301h
	mov	bx,	000Fh
	mov	dx,	0E00h		;row 14
	mov	cx,	30
	push	ax
	mov	ax,	ds
	mov	es,	ax
	pop	ax
	mov	bp,	GetSVGAModeInfoOKMessage
	int	10h
 
;=======	set the SVGA mode(VESA VBE)
 
	mov	ax,	4F02h
	mov	bx,	4180h	;========================mode : 0x180 or 0x143
	int 	10h
 
	cmp	ax,	004Fh
	jnz	Label_SET_SVGA_Mode_VESA_VBE_FAIL
 
;=======	init IDT GDT goto protect mode 
 
	cli			;======close interrupt
 
	db	0x66
	lgdt	[GdtPtr]
 
;	db	0x66
;	lidt	[IDT_POINTER]
 
	mov	eax,	cr0
	or	eax,	1
	mov	cr0,	eax	
 
	jmp	dword SelectorCode32:GO_TO_TMP_Protect
 
[SECTION .s32]
[BITS 32]
 
GO_TO_TMP_Protect:
 
;=======	go to tmp long mode
 
	mov	ax,	0x10
	mov	ds,	ax
	mov	es,	ax
	mov	fs,	ax
	mov	ss,	ax
	mov	esp,	7E00h
 
	call	support_long_mode
	test	eax,	eax
 
	jz	no_support
 
;=======	init temporary page table 0x90000
 
	mov	dword	[0x90000],	0x91007
	mov	dword	[0x90800],	0x91007		
 
	mov	dword	[0x91000],	0x92007
 
	mov	dword	[0x92000],	0x000083
 
	mov	dword	[0x92008],	0x200083
 
	mov	dword	[0x92010],	0x400083
 
	mov	dword	[0x92018],	0x600083
 
	mov	dword	[0x92020],	0x800083
 
	mov	dword	[0x92028],	0xa00083
 
;=======	load GDTR
 
	db	0x66
	lgdt	[GdtPtr64]
	mov	ax,	0x10
	mov	ds,	ax
	mov	es,	ax
	mov	fs,	ax
	mov	gs,	ax
	mov	ss,	ax
 
	mov	esp,	7E00h
 
;=======	open PAE
 
	mov	eax,	cr4
	bts	eax,	5
	mov	cr4,	eax
 
;=======	load	cr3
 
	mov	eax,	0x90000
	mov	cr3,	eax
 
;=======	enable long-mode
 
	mov	ecx,	0C0000080h		;IA32_EFER
	rdmsr
 
	bts	eax,	8
	wrmsr
 
;=======	open PE and paging
 
	mov	eax,	cr0
	bts	eax,	0
	bts	eax,	31
	mov	cr0,	eax
 
	jmp	SelectorCode64:OffsetOfKernelFile
 
;=======	test support long mode or not
 
support_long_mode:
 
	mov	eax,	0x80000000
	cpuid
	cmp	eax,	0x80000001
	setnb	al	
	jb	support_long_mode_done
	mov	eax,	0x80000001
	cpuid
	bt	edx,	29
	setc	al
support_long_mode_done:
	
	movzx	eax,	al
	ret
 
;=======	no support
 
no_support:
	jmp	$
 
;=======	read one sector from floppy
 
[SECTION .s16lib]
[BITS 16]
 
Func_ReadOneSector:
	
	push	bp
	mov	bp,	sp
	sub	esp,	2
	mov	byte	[bp - 2],	cl
	push	bx
	mov	bl,	[BPB_SecPerTrk]
	div	bl
	inc	ah
	mov	cl,	ah
	mov	dh,	al
	shr	al,	1
	mov	ch,	al
	and	dh,	1
	pop	bx
	mov	dl,	[BS_DrvNum]
Label_Go_On_Reading:
	mov	ah,	2
	mov	al,	byte	[bp - 2]
	int	13h
	jc	Label_Go_On_Reading
	add	esp,	2
	pop	bp
	ret
 
;=======	get FAT Entry
 
Func_GetFATEntry:
 
	push	es
	push	bx
	push	ax
	mov	ax,	00
	mov	es,	ax
	pop	ax
	mov	byte	[Odd],	0
	mov	bx,	3
	mul	bx
	mov	bx,	2
	div	bx
	cmp	dx,	0
	jz	Label_Even
	mov	byte	[Odd],	1
 
Label_Even:
 
	xor	dx,	dx
	mov	bx,	[BPB_BytesPerSec]
	div	bx
	push	dx
	mov	bx,	8000h
	add	ax,	SectorNumOfFAT1Start
	mov	cl,	2
	call	Func_ReadOneSector
	
	pop	dx
	add	bx,	dx
	mov	ax,	[es:bx]
	cmp	byte	[Odd],	1
	jnz	Label_Even_2
	shr	ax,	4
 
Label_Even_2:
	and	ax,	0FFFh
	pop	bx
	pop	es
	ret
 
;=======	display num in al
 
Label_DispAL:
 
	push	ecx
	push	edx
	push	edi
	
	mov	edi,	[DisplayPosition]
	mov	ah,	0Fh
	mov	dl,	al
	shr	al,	4
	mov	ecx,	2
.begin:
 
	and	al,	0Fh
	cmp	al,	9
	ja	.1
	add	al,	'0'
	jmp	.2
.1:
 
	sub	al,	0Ah
	add	al,	'A'
.2:
 
	mov	[gs:edi],	ax
	add	edi,	2
	
	mov	al,	dl
	loop	.begin
 
	mov	[DisplayPosition],	edi
 
	pop	edi
	pop	edx
	pop	ecx
	
	ret
 
 
;=======	tmp IDT
 
IDT:
	times	0x50	dq	0
IDT_END:
 
IDT_POINTER:
		dw	IDT_END - IDT - 1
		dd	IDT
 
;=======	tmp variable
 
RootDirSizeForLoop	dw	RootDirSectors
SectorNo		dw	0
Odd			db	0
OffsetOfKernelFileCount	dd	OffsetOfKernelFile
 
DisplayPosition		dd	0
 
;=======	display messages
 
StartLoaderMessage:	db	"Start Loader"
NoLoaderMessage:	db	"ERROR:No KERNEL Found"
KernelFileName:		db	"KERNEL  BIN",0
StartGetMemStructMessage:	db	"Start Get Memory Struct."
GetMemStructErrMessage:	db	"Get Memory Struct ERROR"
GetMemStructOKMessage:	db	"Get Memory Struct SUCCESSFUL!"
 
StartGetSVGAVBEInfoMessage:	db	"Start Get SVGA VBE Info"
GetSVGAVBEInfoErrMessage:	db	"Get SVGA VBE Info ERROR"
GetSVGAVBEInfoOKMessage:	db	"Get SVGA VBE Info SUCCESSFUL!"
 
StartGetSVGAModeInfoMessage:	db	"Start Get SVGA Mode Info"
GetSVGAModeInfoErrMessage:	db	"Get SVGA Mode Info ERROR"
GetSVGAModeInfoOKMessage:	db	"Get SVGA Mode Info SUCCESSFUL!"

当boot.asm和loader.asm准备完成后，在将两文件进行编译生成.bin文件之前需要准备一个名为fat12.inc的文件，fatl2 inc文件是从Boot引导程序中提取出的FAT12文件系统结构。

编写fat12.inc

vim fat12.inc

fat12.inc文件内容：

RootDirSectors	equ	14
SectorNumOfRootDirStart	equ	19
SectorNumOfFAT1Start	equ	1
SectorBalance	equ	17	
 
	BS_OEMName	db	'MINEboot'
	BPB_BytesPerSec	dw	512
	BPB_SecPerClus	db	1
	BPB_RsvdSecCnt	dw	1
	BPB_NumFATs	db	2
	BPB_RootEntCnt	dw	224
	BPB_TotSec16	dw	2880
	BPB_Media	db	0xf0
	BPB_FATSz16	dw	9
	BPB_SecPerTrk	dw	18
	BPB_NumHeads	dw	2
	BPB_hiddSec	dd	0
	BPB_TotSec32	dd	0
	BS_DrvNum	db	0
	BS_Reserved1	db	0
	BS_BootSig	db	29h
	BS_VolID	dd	0
	BS_VolLab	db	'boot loader'
	BS_FileSysType	db	'FAT12   '

将两文件进行编译生成.bin文件

nasm boot.asm -o boot.bin
nasm loader.asm -o loader.bin

创建镜像文件/软盘等相关内容

内容同：在Linux下安装配置bochs，并成功跑一个简单的boot引导（超详细）_What’smean的博客-CSDN博客
如图所示，建议与bochsrc在同一目录下

创建为软盘即fd，大小默认1.44M即可，命名为boot.img

之后为查看创建是否成功

将生成的boot.bin写入img文件中

执行命令

dd if=boot.bin of=boot.img bs=512 count=1 conv=notrunc

这行命令中的if = boot.bin指定输入源文件名，而of=boot .img则指定输出文件名,参数bs=512指定传输的块大小为512B,参数count=1指定写入到目标文件的块数量,参数conv=notrunc规定在写入数据后不截断（改变）输出文件的尺寸大小。

dd if=boot.bin of=boot.img bs=512 count=1 conv=notrunc
执行日志：

将loader.asm写入boot.img镜像中

当loader.asm程序编译结束后，必须将生成的二进制程序loader.bin复制到虚拟软盘镜像文件boot.img中。此处的复制过程与boot.bin程序的写入过程采用了完全不同方法，当boot.bin程序写入到boot.img虚拟软盘镜像文件后，boot.img虚拟软盘已经拥有了FAT12文件系统，那么应该借助挂载命令mount和复制命令cp,把引导加载程序loader.bin复制到文件系统中。

整个复制过程需要执行以下命令:

mount boot.img /media/ -t vfat -o loop 挂载 目录 -t vfat 指定磁盘文件系统
cp loader.bin /media/ 复制到文件系统
sync //强制同步命令
umount /media/ //卸载目录

执行bochs

bochs -f ./bochsrc

一路回车然后输入 c 即可，下图为最终效果图