Add little multiboot stub

[netwatch.git] / aseg / aseg.asm

diff --git a/aseg/aseg.asm b/aseg/aseg.asm
index 51a28111986652c96ce4ca90daed569a721bf123..c086b83b0971ebe211e3e9940fe900063fd65d93 100644 (file)
--- a/aseg/aseg.asm
+++ b/aseg/aseg.asm
@@ -1,130 +1,59 @@
-       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 0x1F, 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