Well, how are you planning on loading your kernel?mgl wrote:Hi!
I have this *problem*, and well, i'm a bit embarrassed of asking for help, because i know it's a really basic, but... here it goes.... how do I copy my kernel to the floppy disk?
Code: Select all
[BITS 16]
[ORG 0x100]
SECTION .text
mov ah,0x4a ; resize used memory
mov bx,0x1000 ; # of paragraphs
int 0x21 ; es is still unmodified
mov ah,0x48 ; allocate a 64k block
mov bx,0x1000 ; # of paragraphs
int 0x21
mov [buffer],ax ; seg address of new block
mov ax,0x3d00 ; open file, read only
mov dx,filename
int 0x21
jc near file_error
mov [file_handle],ax
; PMODE INITALIZATION STATS HERE
; ENABLE A20 LINE AND DISABLE INTS
A20: cli
call .discard_out
call .command_wait
mov al,0xd1
out 0x64,al
call .command_wait
mov al,0xdf
out 0x60,al
call .command_wait
jmp .done
.command_wait: in al,0x64
test al,0x02
jnz .command_wait
ret
.discard_out: in al,0x64
test al,0x01
jnz .read
ret
.read: in al,0x60
jmp .discard_out
.done:
mov ax,cs ; save some values to return to real mode
mov [Real_CS],ax
mov [Real_CS2],ax
lea ax,[Goto_Real]
mov [Real_IP],ax
lea ax,[Goto_Real2]
mov [Real_IP2],ax
xor eax,eax ; set base address in selector table
mov ax,cs
shl eax,4
mov [GDT.Entry1+2],ax
mov [GDT.Entry2+2],ax
mov [GDT.Entry4+2],ax
mov [GDT.Entry5+2],ax
shr eax,16
mov [GDT.Entry1+4],al
mov [GDT.Entry2+4],al
mov [GDT.Entry4+4],al
mov [GDT.Entry5+4],al
xor eax,eax
mov ax,cs
shl eax,4
add eax,gdt0
mov [GDTR.Address],eax
lgdt [GDTR]
File_Move:
;***read a 64k section to buffer
mov ah,0x3f
mov bx,[file_handle]
mov cx,0xffff
mov dx,[buffer]
mov ds,dx
xor dx,dx
int 0x21
mov bx,cs
mov ds,bx
jc near file_error
mov [bytes_read],ax
cli
mov al,0x80 ; disable nmi
out 0x70,al
mov eax,cr0 ; SET PMODE BIT IN CR0
or al,1
mov cr0,eax
jmp SYS_CODE_SEL:Goto_PMode
Goto_PMode:
[BITS 32]
mov ax,SYS_DATA_SEL
mov ds,ax
;***copy from buffer to extended memory
; TRANSFER STUFF IN [buffer]:0 TO FOUR_MEG_DATA_SEL:[TARGET]
xor ecx,ecx
mov cx,[bytes_read]
cld
xor esi,esi
mov si,[buffer]
shl esi,4
mov edi,[Target]
mov ax,FOUR_MEG_DATA_SEL
mov ds,ax
mov es,ax
rep movsb
mov ax,SYS_DATA_SEL
mov ds,ax
mov [Target],edi
jmp REAL_CODE_SEL:Goto_16bit_Pmode
Goto_16bit_Pmode:
[BITS 16]
mov ax,REAL_DATA_SEL
mov ds,ax
mov es,ax
mov eax,cr0
and al,0xFE
mov cr0,eax
jmp far [Real_IP]
Goto_Real:
mov ax,cs
mov ds,ax
mov es,ax
mov al,0x00 ; enable nmi
out 0x70,al
sti
mov ax,[bytes_read]
cmp ax,0xffff
je near File_Move
mov ah,0x3e ; close file
mov bx,[file_handle]
int 0x21
;***CALL KERNEL FILE***
cli
mov al,0x80 ; disable nmi
out 0x70,al
mov eax,cr0 ; SET PMODE BIT IN CR0
or al,1
mov cr0,eax
jmp SYS_CODE_SEL:Setup_Kernel
Setup_Kernel:
[BITS 32]
mov ax,FOUR_MEG_DATA_SEL
mov ds,ax
mov es,ax
mov gs,ax
mov fs,ax
mov ss,ax
mov esp,0x3fffff
call KERNEL_SEL:0x100000
jmp REAL_CODE_SEL:Kernel_Done
Kernel_Done:
[BITS 16]
mov ax,REAL_DATA_SEL
mov ds,ax
mov es,ax
mov ss,ax
mov gs,ax
mov fs,ax
mov esp,0xffff
mov eax,cr0
and al,0xFE
mov cr0,eax
jmp far [Real_IP2]
Goto_Real2:
mov ax,cs
mov ds,ax
mov es,ax
mov ss,ax
mov gs,ax
mov fs,ax
mov al,0x00 ; enable nmi
out 0x70,al
sti
jmp exit
file_error: mov ah,0x3e ; close file
mov bx,[file_handle]
int 0x21
mov dx,error_msg
mov ah,0x09
int 0x21
jmp exit
exit: mov ah,0x49 ; free memory block
mov dx,[buffer]
mov es,dx
int 0x21
mov ah,0x4c
int 0x21
SECTION .data
buffer: dw 0
file_handle: dw 0
error_msg: db 'Error: could not open ',0x22,'kernel32.bin',0x22,'$'
filename: db 'KERNEL32.BIN',0x00
bytes_read: dw 0
Real_IP: dw 0
Real_CS: dw 0
Real_IP2: dw 0
Real_CS2: dw 0
Target: dd 0x100000
GDTR:
.Size: dw GDT_END
.Address: dd 0
gdt0 equ $ ; null entry
GDT:
.Entry0: dw 0 ; limit 15:0
dw 0 ; base 15:0
db 0 ; base 23:16
db 0 ; type
db 0 ; limit 19:16, flags
db 0 ; base 31:24
SYS_CODE_SEL equ $-gdt0 ; code segment descriptor
.Entry1: dw 0xFFFF
dw 0x0 ; base
db 0x0 ; base
db 0x9A ; present, ring 0, code, non-conforming, readable
db 0x40 ; 32 bit
db 0
SYS_DATA_SEL equ $-gdt0 ; data segment descriptor
.Entry2: dw 0xFFFF
dw 0x0 ; base
db 0x0 ; base
db 0x92 ; present, ring 0, data, expand-up, writable
db 0x40 ; 32 bit
db 0
FOUR_MEG_DATA_SEL equ $-gdt0 ; 4meg data segment descriptor
.Entry3: dw 0x03ff
dw 0x0 ; base
db 0x0 ; base
db 0x92 ; present, ring 0, data, expand-up, writable
db 0xc0 ; 4k pages, 32 bit
db 0
REAL_CODE_SEL equ $-gdt0 ; code segment descriptor for 16 bit mode
.Entry4: dw 0xFFFF
dw 0x0 ; base
db 0x0 ; base
db 0x9A ; present, ring 0, code, non-conforming, readable
db 0x00 ; 16 bit
db 0
REAL_DATA_SEL equ $-gdt0 ; data segment descriptor for 16 bit mode
.Entry5: dw 0xFFFF
dw 0x0 ; base
db 0x0 ; base
db 0x92 ; present, ring 0, data, expand-up, writable
db 0x00 ; 16 bit
db 0
KERNEL_SEL equ $-gdt0 ; 4meg code segment descriptor
.Entry6: dw 0x03ff
dw 0x0 ; base
db 0x0 ; base
db 0x9A ; present, ring 0, code, non-conforming, readable
db 0xc0 ; 4k pages, 32 bit
db 0
GDT_END equ $-gdt0 -1
SECTION .bss
Actually, based on the org statement and the DOS calls, I'd say this is a DOS *.com file, not a bootsector at all. If it were a fat bootsector, it would have the filesystem header into in it.hckr83 wrote:ok this I'm pretty sure is a fat12 bootsector
I tried running that on windows using djgpp and when I tried to link the blank kernel it said:carbonBased wrote:Dunno if it'll help, but a while back I wrote a tutorial on how to write a kernel that can be booted by grub, which also includes info on how to install grub on a virtual or real floppy:
That's because DJGPP doesn't support elf objects, only coff. Either switch nasm to output a coff object, or use an elf based toolkit (cygwin).sfpiano wrote:I tried running that on windows using djgpp and when I tried to link the blank kernel it said:carbonBased wrote:Dunno if it'll help, but a while back I wrote a tutorial on how to write a kernel that can be booted by grub, which also includes info on how to install grub on a virtual or real floppy:
start.o: file not recognized: File format not recognized