grub thing

Aleph One <[email protected]> Wed, 1 Mar 2006 07:10:33 +0000

Newsgroups	org.kernel.vger.linux-assembly
Message-ID	<[email protected]>

hello all!

i'm _that_ boy (again) from last christmas.. hehehe didn't think i'd reach this far though and i just wanna clarify something.

i'm looking at a disassembly of grub's stage 1. and i wanna know why it need's to CLI before setting up the environment?? i tried to interpret it line by line and this is what i have so far

 00007C4A  FA			cli			; disable interrupt
 00007C4B  80CA80		or dl,0x80          ; correct boot drive byte
 00007C4E  EA537C0000	jmp 0x0:0x7c53	; jmp to next inst
 00007C53  31C0		xor ax,ax           ; zero ax 
 00007C55  8ED8		mov ds,ax		; zero data segment 
 00007C57  8ED0		mov ss,ax		; zero stack segment 
 00007C59  BC0020		mov sp,0x2000	; 8 kilobytes
 00007C5C  FB			sti			; enable interrupt

also, since the origin is at 0000:7c00h i figured that must imply that "mov sp, 0x2000" means that the stack starts at 0x7c00+0x2000 = 9c000 right?

today is ash wednesday. tidings.