- org 0x0
+ org 0xA8000
[bits 16]
entry:
-; mov al, 0x01 ; Say where we are.
-; out 0x80, al
- 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
- jmp 0xA800:entry2 ; Long jump to a correct cs.
+ jmp 0xA800:(entry2-0xA8000) ; Long jump to a correct cs.
entry2:
-; mov al, 0x02
-; out 0x80, al
- lgdt [gdtr] ; Set up a new GDT.
+ lgdt [(gdtr-0xA8000)] ; Set up a new GDT.
mov eax, 0x1
mov cr0, eax ; ... and enter pmode!
- mov al, 0x03 ; Say we got here.
- out 0x80, al
- jmp long 0x10:(continue+0xA8000) ; Now longjmp into the new code.
+ jmp long 0x10:continue ; Now longjmp into the new code.
[bits 32]
continue:
-; mov al, 0x04 ; Now we're in protected mode.
-; out 0x80, al
-
mov ax, 0x08 ; Set up segment selectors.
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax
- mov esp, 0x1fffffff
-
-; mov al, 0x05
-; out 0x80, al
-
- mov al, [(cstat + 0xA8000)]
- add al, 1
- out 0x80, al
- mov [(cstat + 0xA8000)], al
-
- mov eax, 0x11223344
- mov dword [(status + 0xA8000)], eax
-
- mov dx, 0xCF8 ; save off the old config value
- in dword eax, dx
- mov [esp-4], eax
-
- mov eax, 0x80000070 ; load in smramc
- out dx, eax
- mov dx, 0xCFC
- in byte al, dx
- mov [esp-5], al
- and al, 0xF3 ; Allow graphics access
- or al, 0x08
- out dx, al
+ mov esp, [dataptr] ; Load stack pointer.
+
+ mov al, [needclear] ; Has the aseg been run before?
+ cmp al, 0 ; If so,
+ jz noclear ; don't clear BSS.
+ mov al, 0 ; Otherwise, clear BSS.
+ mov edi, [dataptr+4]
+ mov ecx, [dataptr+8]
+ rep stosb
+ mov [needclear], al
- xor eax, eax
- mov dx, 0x3D4
- in byte al, dx
- mov [esp-6], al ; save off the old VGA command
- mov al, 0xC
- out dx, al
- inc dx
- in al, dx
- mov ah, al
- dec dx
- mov al, 0xD
- out dx, al
- inc dx
- in al, dx
- shl eax, 1
- add eax, 0xB8000 ; yay
- mov byte [eax+0], '1'
- mov byte [eax+1], 0xA0
- mov byte [eax+2], '5'
- mov byte [eax+3], 0xA0
- mov byte [eax+4], '-'
- mov byte [eax+5], 0xA0
- mov byte [eax+6], '4'
- mov byte [eax+7], 0xA0
- mov byte [eax+8], '1'
- mov byte [eax+9], 0xA0
- mov byte [eax+10], '2'
- mov byte [eax+11], 0xA0
-
- mov dx, 0x3D4
- mov al, [esp-6]
- out dx, al
-
-
- mov dx, 0xCFC ; restore smramc
- mov al, [esp-5]
- out dx, al
-
- mov dx, 0xCF8 ; restore the old config value
- mov eax, [esp-4]
- out dx, eax
-
- mov al, 0x40 ; ack the periodic IRQ
- mov dx, 0x834
- out dx, al
-
- mov dx, 0x830
- in al, dx
- or al, 0x02 ; now ack the SMI itself
- and al, 0xBF
- out dx, al
- or al, 0x40
- out dx, al
+noclear:
+ mov eax, [dataptr+12] ; Load target jump address
+ call eax ; then jump into C.
rsm ; and leave SMM
align 0x4
gdtr:
- db 0x27, 0x00
- dd (gdt + 0xA8000)
+ 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
-TIMES 512-($-$$) DB 0
-status:
- dd 0xAA55AA55
-cstat:
- db 0x00
+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