I using the bochs for x86-64 version. I tried to let the code run under the fully 64bit mode, But when the system enter the compatibility mode, code jump to the
.code64 area execute the instruction. But the 64bit opcode can't correct execute.
The system look like not enter 64bit mode, just always in the compatibility mode.
Who can help me to fix this issue?
Thanks.
Code: Select all
.code16
.text
.global _start
_start:
movw %cs,%ax
movw %ax,%ds
movw %ax,%es
#Enable A20
call empty_8042
movb $0xd1,%al
outb %al,$0x64
call empty_8042
movb $0xdf,%al
outb %al,$0x60
call empty_8042
cli
lgdt gdt_48
movl $0x00000001,%eax
movl %eax,%cr0
.byte 0x66,0xea
.long 0x90000+ProtectMode
.word 0x08
.code32
ProtectMode:
movw $0x10,%ax
movw %ax,%ds
movw %ax,%es
movw %ax,%ss
xorl %esi,%esi
movl $0x00001001,(,%esi,8)
movl $0x00000000,4(,%esi,8)
movl $0x100,%esi
movl $0x00004001,0(,%esi,8)
movl $0x00000000,4(,%esi,8)
xorl %esi,%esi
movl $0x00002001,0x1000(,%esi,8)
movl $0x00000000,0x1004(,%esi,8)
movl $0x00003001,0x2000(,%esi,8)
movl $0x00000000,0x2004(,%esi,8)
movl $256,%ecx
movl $0x00000001,%ebx
NextPage_0x0000000000000000:
movl %ebx,0x3000(,%esi,8)
movl $0x00000000,0x3004(,%esi,8)
incl %esi
addl $0x1000,%ebx
decl %ecx
jnz NextPage_0x0000000000000000
xorl %esi,%esi
movl $0x00005001,0x4000(,%esi,8)
movl $0x00000000,0x4004(,%esi,8)
movl $0x00006001,0x5000(,%esi,8)
movl $0x00000000,0x5004(,%esi,8)
movl $256,%ecx
movl $0x00000001,%ebx
NextPage_0x0000800000000000:
movl %ebx,0x6000(,%esi,8)
movl $0x00000000,0x6004(,%esi,8)
incl %esi
addl $4096,%ebx
decl %ecx
jnz NextPage_0x0000800000000000
/*Enable PAE*/
xorl %eax,%eax
btsl $5,%eax
movl %eax,%cr4
movl $0,%eax
movl %eax,%cr3
movl $0xc0000080,%ecx /*EFER MSR number*/
rdmsr /*Read EFER*/
orl $0x100,%eax /*Set LME=1*/
wrmsr /*Write EFER*/
/*Page Enable*/
xorl %eax,%eax
btsl $31,%eax
btsl $0,%eax
movl %eax,%cr0
ljmp $0x08,$(0x90000+ProtectMode64)
.org 0x200
.code64
.globl ProtectMode64
ProtectMode64:
[color=red]/*the 64bit instruction opcode is detached two opcode to execute, one is "0x48" just "DEC %eax", the other is "xor %eax,%eax"*/[/color]
/*Enable PAE*/
xorq %rax,%rax
btsq $5,%rax
btsq $7,%rax
movq %rax,%cr4
movq $0x0,%rax
movq %rax,%cr3
movl $1|(1<<1)|(1<<4)|(1<<5)|(1<<16)|(1<<18)|(1<<31),%eax
movq %rax, %cr0
movq $0x80000,%rsp
movq $0x80000,%rbp
lgdt gdt_80
movq c_start(%rip),%rax
pushq $0 # fake return address to stop unwinder
pushq $0x08 # set correct cs
pushq %rax # target address in negative space
lretq
idt_48:
.word 0
.word 0,0
idt_80:
.word 0
.quad 0
gdt32:
.word 0,0,0,0
.word 0xffff #Segment limit 15:0
.word 0x0000 #Base address 15:0
.word 0x9800
.word 0x00CF
.word 0xffff
.word 0x0000
.word 0x9200
.word 0x00CF
gdt_48:
.word 0x8000
.long gdt32+0x90000
gdt64:
.quad 0x0000000000000000 /*NULL descriptor*/
.quad 0x00af9a000000ffff /*CS*/
.quad 0x00cf92000000ffff /*DS,SS*/
gdt_80:
.word 0x8000
.quad gdt64+0x90000
.code16
empty_8042:
inb $0x64,%al
testb $0x1,%al
jz outbuff_empty
inb $0x60,%al
jmp empty_8042
.code64
c_start:
.end