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From: Aleph One <amerei@gmail.com>
To: linux-assembly@vger.kernel.org
Subject: grub thing
Date: Wed, 1 Mar 2006 07:10:33 +0000	[thread overview]
Message-ID: <20060301071033.0c9eb1d4.amerei@gmail.com> (raw)
In-Reply-To: <200602222126.57346.thiago.silva@kdemail.net>

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.

  parent reply	other threads:[~2006-03-01  7:10 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-02-22 21:26 nasm -f bin / Elf format Thiago Silva
2006-02-23  0:32 ` Brian Raiter
2006-03-01  7:10 ` Aleph One [this message]
2006-03-01 13:34   ` grub thing Ricardo Nabinger Sanchez
2006-03-02  6:49     ` Aleph One
2006-03-01 14:42   ` Marcin Kościelnicki
2006-03-01 18:08     ` Ricardo Nabinger Sanchez
2006-03-02  6:46     ` Aleph One

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