FAR Jmp problem

[ksk]

Hi,

I am almost on the verge of completing my bootloader. These are the things that I have done

1. relocate by bootloader from 0x7C00 to 0x8000:0
2. Enable A20
3. Then jump to the relocated bootloader
4. Then I loaded my kernel at 0x1000:0
5. But when I try to do a far jmp to that address(to execute my kernel) I get
        
         rip > cs error in Bochs

I have tried the following

a) jmp 0x1000:0x0

b) krnl_load_address dw 0x1000
   jmp word far krnl_load_address:0x0

and many others............

But still I am not able to get What I want.

PS:
   I am still in real mode but I have enabled A20 (but I think both have nothing to do with my problem - except ofcourse the 64K segment limit)

[St8ic]

Hmmmm....If I'm understanding correctly I think sticking an offset and segment on the end should work:

DW 07E00h ; offset
DW 00000h ; segment

Or where ever they are. This would be jumping to <DB 0EAh>.

[ksk]

hi
Could you explain in detail. How did you get <DB 0EAh>?

In INtel manual it says far jump can be done only by a memory (In real mode). Any idea how ?

Thanks

[St8ic]

I didn't understand the question. The code I gave is a little trick to jump to a location on disk (in this case the second sector, that would be DB 0EAh). If you didn't use this offset/segment crap then you'd crash and burn because the location is too close to sector 1, where this code is.

I think you're jumping in memory address, not disk sector. Sorry for the incovenience I may have caused.

[Ramanan]

y don't u use like this instead of jmp....

mov ax, 0x1000
push ax
xor ax, ax
push ax
retf

rgds,
YogaRamanan.T