问题描述
我从今年夏天开始创建一个操作系统,它是一个在保护模式下工作的 32 位操作系统。我需要创建一种方法来使 BIOS 中断,所以我需要以实模式传递,在 16 位之前,我成功地传递到 16 位,但我不确定我在代码末尾是否以实模式传递。我尝试通过示例切换视频模式,但我的模拟器 Boch 写道:
00012417016e[CPU0 ] interrupt(real mode) vector > idtr.limit
00012417016e[CPU0 ] interrupt(real mode) vector > idtr.limit
00012417016e[CPU0 ] interrupt(real mode) vector > idtr.limit
00012417016i[CPU0 ] real mode
00012417016i[CPU0 ] CS.d_b = 16 bit
00012417016i[CPU0 ] SS.d_b = 16 bit
00012417016i[CPU0 ] | EAX=00004c00 EBX=00000123 ECX=00000000 EDX=00001034
00012417016i[CPU0 ] | ESP=0009f000 EBP=0009effc ESI=00000123 EDI=0000ffde
00012417016i[CPU0 ] | IOPL=0 id vip codec vm RF nt of df IF tf sf zf af pf cf
00012417016i[CPU0 ] | SEG selector base limit G D
00012417016i[CPU0 ] | SEG sltr(index|ti|rpl) base limit G D
00012417016i[CPU0 ] | CS:0000( 0004| 0| 0) 00000000 0000ffff 0 0
00012417016i[CPU0 ] | DS:07c0( 0005| 0| 0) 00007c00 0000ffff 0 0
00012417016i[CPU0 ] | SS:8000( 0005| 0| 0) 00080000 0000ffff 0 0
00012417016i[CPU0 ] | ES:07c0( 0005| 0| 0) 00007c00 0000ffff 0 0
00012417016i[CPU0 ] | FS:0000( 0005| 0| 0) 00000000 0000ffff 0 0
00012417016i[CPU0 ] | GS:0000( 0005| 0| 0) 00000000 0000ffff 0 0
00012417016i[CPU0 ] | EIP=00001d63 (00001d63 )
00012417016i[CPU0 ] | CR0=0x00000010 CR1=0 CR2=0x00000000
00012417016i[CPU0 ] | CR3=0x00000000 CR4=0x00000000
00012417016i[CPU0 ] >> int 0x21 : CD21
00012417016e[CPU0 ] exception(): 3rd (13) exception with no resolution,shutdown status is 00h,resetting
00012417016i[SYS ] bx_pc_system_c::Reset(SOFTWARE) called
我切换到实模式的汇编代码是:
global go16
;______________________________________________________________________________________________________
;Switch to 16-bit real Mode
;IN/OUT: nothing
go16:
[BITS 32]
;cli ;Clear interrupts
pop edx ;save return location in edx
jmp 0x20:PM16 ;Load CS with selector 0x20
;For go to 16-bit real mode,first we have to go to 16-bit protected mode
[BITS 16]
PM16:
mov ax,0x28 ;0x28 is 16-bit protected mode selector.
mov ss,ax
mov ds,ax
mov es,ax
mov gs,ax
mov fs,ax
mov sp,0x7c00+0x200 ;Stack hase base at 0x7c00+0x200
mov eax,cr0
mov [savcr0],eax
and eax,0xfffffffe ;Clear protected enable bit in cr0
mov cr0,eax
jmp 0:realMode ;Load CS and IP
realMode:
;Load segment registers with 16-bit Values.
mov ax,0
mov ds,ax
mov ss,0x7c00+0x200
mov ax,0x07c0
mov ds,ax
mov ax,0x8000
mov ss,0xf000
lidt [idt_real] ;Load real mode interrupt vector table
sti
mov ax,4c00h
int 10h
cli
hlt
;Real mode interrupt vector table
idt_real:
dw 0x3ff ; 256 entries,4b each = 1K
dd 0 ; Real Mode IVT @ 0x0000
savcr0:
dd 0
感谢您的帮助,如果您需要其他元素,请在评论中向我询问
解决方法
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