org 0xA8000
[bits 16]
entry:
- mov ax, 0xA800
- mov ds, ax ; Take us out of flat unreal mode, and
- mov es, ax ; put us in true real mode.
+ mov ax, 0xA800 ; Take us out of flat unreal mode,
+ mov ds, ax ; and put us in true real mode.
+ mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax
mov fs, ax
mov gs, ax
mov ss, ax
- mov esp, [dataptr]
-
- mov al, [needclear]
- cmp al, 0
- jz noclear
- mov al, 0 ; clear BSS
- mov edi, [dataptr+4]
- mov ecx, [dataptr+8]
- rep stosb
- mov [needclear], al
+ mov esp, [dataptr] ; Load stack pointer.
-noclear:
- mov eax, [dataptr+12] ; jump into C
- call eax
-
- mov al, 0x40 ; ack the periodic IRQ
- mov dx, 0x834
- out dx, al
-
- mov dx, 0x830 ; now ack the SMI itself
- in al, dx
- or al, 0x02
- and al, 0xBF
- out dx, al
- or al, 0x40
- out dx, al
+ mov eax, [dataptr+4] ; Load target jump address
+ call eax ; then jump into C.
rsm ; and leave SMM
align 0x4
gdtr:
- db 0x27, 0x00
+ db 0x17, 0x00
dd gdt
align 0x4
gdt:
- db 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+ db 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ; initial null entry
db 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x93, 0xCF, 0x00 ; data segment
db 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x9B, 0xCF, 0x00 ; code segment
- db 0xFF, 0xFF, 0x00, 0x80, 0x0A, 0x9B, 0xCF, 0x00 ; code segment for trampoline
-
-needclear:
- db 0x01
dataptr:
; 4 bytes of stack top
- ; 4 bytes of BSS start
- ; 4 bytes of BSS length
; 4 bytes of C entry point
; These show up