这是我的64位引导加载程序的最小内核。我试图利用IN / OUT指令。在这个例子中，程序直到＆＃34; X＆＃34; - 打印点（qemu屏幕一直闪烁）才结束。你知道为什么吗？
boot.asm：
[org 0x7c00]
KERNEL_ADDRESS equ 0x100000
cli
lgdt [gdt_descriptor]
;Switch to PM
mov eax, cr0
or eax, 0x1
mov cr0, eax
jmp 0x8:init_pm
[bits 32]
init_pm :
mov ax, 0x10
mov ds, ax
mov ss, ax
mov es, ax
mov fs, ax
mov gs, ax
call build_page_tables
;Enable PAE
mov eax, cr4
or eax, 1 << 5
mov cr4, eax
;# Optional : Enable global-page mechanism by setting CR0.PGE bit to 1
mov eax, cr4
or eax, 1 << 7
mov cr4, eax
;Load CR3 with PML4 base address
;NB: in some examples online, the address is not offseted is it seems to
;be in the proc datasheet... if you were wondering about this strange thing.
mov eax, 0x1000
mov cr3, eax
;Set LME bit in EFER register (address 0xC0000080)
mov ecx, 0xC0000080 ;operand of 'rdmsr' and 'wrmsr'
rdmsr ;read before pr ne pas écraser le contenu
or eax, 1 << 8 ;eax : operand de wrmsr
wrmsr
;Enable paging by setting CR0.PG bit to 1
mov eax, cr0
or eax, (1 << 31)
mov cr0, eax
;Load 64-bit GDT
lgdt [gdt64_descriptor]
;Jump to code segment in 64-bit GDT
jmp 0x8:init_lm
[bits 64]
init_lm:
mov ax, 0x10
mov fs, ax ;other segments are ignored
mov gs, ax
mov rbp, 0x90000 ;set up stack
mov rsp, rbp
;Load kernel from disk
xor ebx, ebx ;upper 2 bytes above bh in ebx is for cylinder = 0x0
mov bl, 0x2 ;read from 2nd sectors
mov bh, 0x0 ;head
mov ch, 1 ;read 1 sector
mov rdi, KERNEL_ADDRESS
call ata_chs_read
jmp KERNEL_ADDRESS
jmp $
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;[bits 16]
;; http://wiki.osdev.org/ATA_in_x86_RealMode_%28BIOS%29
;load_loader:
;;!! il faut rester sur le meme segment, ie <0x10000 (=2**16)
;mov bx, LOADER_OFFSET
;mov dh, 1 ;load 1 sector (max allowed by BIOS is 128)
;mov dl, 0x80 ;drive number
;mov ah, 0x02 ;read function
;mov al, dh
;mov ch, 0x00 ;cylinder
;mov dh, 0x00 ;head
;; !! Sector is 1-based, and not 0-based
;mov cl, 0x02 ;1st sector to read
;int 0x13
;ret
[bits 32]
build_page_tables:
;PML4 starts at 0x1000
;il faut laisser la place pour tte la page PML4/PDP/PD ie. 0x1000
;PML4 @ 0x1000
mov eax, 0x2000 ;PDP base address
or eax, 0b11 ;P and R/W bits
mov ebx, 0x1000 ;MPL4 base address
mov [ebx], eax
;PDP @ 0x2000; maps 64Go
mov eax, 0x3000 ;PD base address
mov ebx, 0x2000 ;PDP physical address
mov ecx, 64 ;64 PDP
build_PDP:
or eax, 0b11
mov [ebx], eax
add ebx, 0x8
add eax, 0x1000 ;next PD page base address
loop build_PDP
;PD @ 0x3000 (ends at 0x4000, fits below 0x7c00)
; 1 entry maps a 2MB page, the 1st starts at 0x0
mov eax, 0x0 ;1st page physical base address
mov ebx, 0x3000 ;PD physical base address
mov ecx, 512
build_PD:
or eax, 0b10000011 ;P + R/W + PS (bit for 2MB page)
mov [ebx], eax
add ebx, 0x8
add eax, 0x200000 ;next 2MB physical page
loop build_PD
;(tables end at 0x4000 => fits before Bios boot sector at 0x7c00)
ret
;=============================================================================
; ATA read sectors (CHS mode)
; Max head index is 15, giving 16 possible heads
; Max cylinder index can be a very large number (up to 65535)
; Sector is usually always 1-63, sector 0 reserved, max 255 sectors/track
; If using 63 sectors/track, max disk size = 31.5GB
; If using 255 sectors/track, max disk size = 127.5GB
; See OSDev forum links in bottom of [http://wiki.osdev.org/ATA]
;
; @param EBX The CHS values; 2 bytes, 1 byte (BH), 1 byte (BL) accordingly
; @param CH The number of sectors to read
; @param RDI The address of buffer to put data obtained from disk
;
; @return None
;=============================================================================
[bits 64]
ata_chs_read: pushfq
push rax
push rbx
push rcx
push rdx
push rdi
mov rdx,1f6h ;port to send drive & head numbers
mov al,bh ;head index in BH
and al,00001111b ;head is only 4 bits long
or al,10100000b ;default 1010b in high nibble
out dx,al
mov rdx,1f2h ;Sector count port
mov al,ch ;Read CH sectors
out dx,al
mov rdx,1f3h ;Sector number port
mov al,bl ;BL is sector index
out dx,al
mov rdx,1f4h ;Cylinder low port
mov eax,ebx ;byte 2 in ebx, just above BH
mov cl,16
shr eax,cl ;shift down to AL
out dx,al
mov rdx,1f5h ;Cylinder high port
mov eax,ebx ;byte 3 in ebx, just above byte 2
mov cl,24
shr eax,cl ;shift down to AL
out dx,al
mov rdx,1f7h ;Command port
mov al,20h ;Read with retry.
out dx,al
.still_going: in al,dx
test al,8 ;the sector buffer requires servicing.
jz .still_going ;until the sector buffer is ready.
mov rax,512/2 ;to read 256 words = 1 sector
xor bx,bx
mov bl,ch ;read CH sectors
mul bx
mov rcx,rax ;RCX is counter for INSW
mov rdx,1f0h ;Data port, in and out
rep insw ;in to [RDI]
pop rdi
pop rdx
pop rcx
pop rbx
pop rax
popfq
ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
[bits 16]
GDT:
;null :
dd 0x0
dd 0x0
;code :
dw 0xffff ;Limit
dw 0x0 ;Base
db 0x0 ;Base
db 10011010b ;1st flag, Type flag
db 11001111b ;2nd flag, Limit
db 0x0 ;Base
;data :
dw 0xffff
dw 0x0
db 0x0
db 10010010b
db 11001111b
db 0x0
gdt_descriptor :
dw $ - GDT - 1 ;16-bit size
dd GDT ;32-bit start address
[bits 32]
;see manual 2, §4.8: most fields are ignored in long mode
GDT64:
;null;
dq 0x0
;code
dd 0x0
db 0x0
db 0b10011000
db 0b00100000
db 0x0
;data
dd 0x0
db 0x0
db 0b10010000
db 0b00000000
db 0x0
gdt64_descriptor :
dw $ - GDT64 - 1 ;16-bit size
dd GDT64 ;32-bit start address
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
[bits 16]
times 510 -($-$$) db 0
dw 0xaa55
build.sh：
#!/bin/bash
nasm -f bin boot.asm -o boot.bin
nasm -f elf64 loader.asm -o loader.o
gcc -m64 -c main.c
ld -Ttext 0x100000 -o kernel.elf loader.o main.o
objcopy -R .note -R .comment -S -O binary kernel.elf kernel.bin
dd if=/dev/zero of=image.bin bs=512 count=2880
dd if=boot.bin of=image.bin conv=notrunc
dd if=kernel.bin of=image.bin conv=notrunc bs=512 seek=1
rm ./boot.bin ./kernel.bin ./main.o ./loader.o ./kernel.elf
qemu-system-x86_64 image.bin
main.c：
static inline unsigned char inb (unsigned short int port)
{
unsigned char value;
asm volatile ("in %1, %0" : "=a"(value) : "Nd"(port));
return value;
}
int main(void)
{
unsigned char val;
val = inb(0xCFC);
char * vga = (char *) 0xb8000 ;
*vga = 'X';
while(1){};
return 1;
}