; Boot sector for GeekOS
; Copyright (c) 2001,2004 David H. Hovemeyer <daveho@cs.umd.edu>
; Copyright (c) 2003, Jeffrey K. Hollingsworth <hollings@cs.umd.edu>
-; $Revision: 1.4 $
+; Copyright (c) 2008, Jack Lange <jarusl@cs.northwestern.edu
+; Copyright (c) 2008, Peter Dinda <pdinda@northwestern.edu
+; $Revision: 1.8 $
; This is free software. You are permitted to use,
; redistribute, and modify it as specified in the file "COPYING".
[ORG 0x0]
BeginText: ; needed to calculate padding bytes to fill the sector
-
; Copy the boot sector into INITSEG.
mov ax, BOOTSEG
mov ds, ax ; source segment for string copy
cmp word [sec_count], bx
jl .again
+
+
load_kernel:
; Load the kernel image from sectors KERN_START_SEC..n of the
; floppy into memory at KERNSEG. Note that there are 128 sectors
; Figure out start sector and max sector
mov ax, word [kernelStart]
- mov word [sec_count], ax
+ mov word [sec_count], aX
add ax, word [kernelSize]
mov word [max_sector], ax
-.again:
- mov ax, [sec_count] ; logical sector on the floppy
-; mov dx, ax
-; call PrintHex
-; call PrintNL
- push ax ; 1st param to ReadSector (log sec num)
- sub ax, [kernelStart] ; convert to 0-indexed
- mov cx, ax ; save in cx
- shr ax, 7 ; divide by 128
- shl ax, 12 ; ...and multiply by 0x1000
- add ax, KERNSEG ; ...to get base relative to KERNSEG
-; mov dx, ax
-; call PrintHex
-; call PrintNL
- push ax ; 2nd param to ReadSector (seg base)
- and cx, 0x7f ; mod sector by 128
- shl cx, 9 ; ...and multiply by 512
- push cx ; to get offset in segment (3rd parm)
-; mov dx, cx
-; call PrintHex
-; call PrintNL
-
-
- ; read the sector from the floppy
- call ReadSector
- add sp, 6 ; clear 3 word params
-
-
- ; on to next sector
- inc word [sec_count]
-
- ; have we loaded all of the sectors?
- mov bx, word [max_sector]
- cmp word [sec_count], bx
- jl .again
-
-load_vm:
- ; Load the guest image starting at 1MB
- ; floppy into memory at KERNSEG. Note that there are 128 sectors
- ; per 64K segment. So, when figuring out which segment to
- ; load the sector into, we shift right by 7 bits (which is
- ; equivalent to dividing by 128).
- ; Figure out start sector and max sector
- mov ax, word [vmStart]
- mov word [sec_count], ax
- add ax, word [vmSize]
- mov word [max_sector], ax
+
.again2:
mov ax, [sec_count] ; logical sector on the floppy
push ax ; 1st param to ReadSector (log sec num)
- mov dx, ax
- call PrintHex
- call PrintNL
+; mov dx, ax
+; call PrintHex
+; call PrintNL
mov ax, VMSEG ; ...to get base relative to VMSEG
push ax ; 2nd param to ReadSector (seg base)
mov ax, 2000h ; Always write at the start of the segment
push ax ; 3rd parameter
- mov dx, ax
- call PrintHex
- call PrintNL
+; mov dx, ax
+; call PrintHex
+; call PrintNL
; read the sector from the floppy
call ReadSector
add sp, 6 ; clear 3 word params
- push 9000h
+ push VMSEG
pop es
- mov dx, word [es:2000] ;
- call PrintHex
- call PrintNL
+; mov dx, word [es:2000h] ;
+; call PrintHex
+; call PrintNL
push cs
pop es
mov si, bootsect_gdt
- mov ax, 0x8700 ;
+ mov ah, 87h
+
+ mov cx, 100h
+
int 0x15
+
adc ax, 0
- mov dx, ax
- call PrintHex
- call PrintNL
+; mov dx, ax
+; call PrintHex
+; call PrintNL
+
+
pop es ;
pop bx
mov bx, word [max_sector]
cmp word [sec_count], bx
- jmp .out
+
+.stall
+; jmp .skip
jl .again2
-.out:
+.skip
; Now we've loaded the setup code and the kernel image.
; Jump to setup code.
jmp SETUPSEG:0
xor dl, dl ; hard code drive=0
mov bx, [bp+4] ; offset goes in bx
; (es:bx points to buffer)
-
-
; Call the BIOS Read Diskette Sectors service
int 0x13
-
+
; If the carry flag is NOT set, then there was no error
; and we're done.
jnc .done
dw 0,0,0,0
dw 0,0,0,0
bootsect_src:
- dw 0x200-1
+ dw 0xffff
bootsect_src_base:
- db 0,02,9 ; ! base = 0x092000
+ db 0,0x20,0x08 ; ! base = 0x082000
db 0x93 ; ! typbyte
dw 0 ; ! limit16,base24 =0
bootsect_dst:
- dw 0x200-1
+ dw 0xffff
bootsect_dst_base:
db 0,0,0x10 ; ! base = 0x100000
db 0x93 ; ! typbyte
kernelSize:
dw NUM_KERN_SECTORS
- ;; part of pfat boot record
-vmStart:
- dw 1+NUM_SETUP_SECTORS+NUM_KERN_SECTORS
- ;; part of pfat boot record
-vmSize:
- dw NUM_VM_KERNEL_SECTORS
; Finish by writing the BIOS signature to mark this as
