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b1528932



Joined: 21 May 2010
Posts: 287
b1528932
when cpu execute first instruction at 0xF00:0xFFF0, what is the state of registers?
ok, CS is 0xF000, and IP is 0xFFF0.
what about rest?

im disassembling my bios, and finst instruction is mov al,0xE8
second is stos
what is under es and di?
third instruction is indirect far call.
call. what is sp and sp?


HELP ME PLZ!
Post 31 Jul 2010, 17:50
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edfed



Joined: 20 Feb 2006
Posts: 4238
Location: 2018
edfed
http://docs.huihoo.com/help-pc/misc-cold_boot.html

i think di is set to 0 too, the first thing done before anything is IVT initialisation.
Post 31 Jul 2010, 19:09
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
http://www.intel.com/products/processor/manuals/

Download volume 3A an read chapter 9. But for a quick answer, EDI, EBP and ESP are zero (volume 2 of AMD says the same but for RDI, RBP and RSP).
Post 31 Jul 2010, 19:10
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b1528932



Joined: 21 May 2010
Posts: 287
b1528932
thx.
so its in manuals? i didnt know.

what about stack? does 0 is a valid address for top of stack?
Post 31 Jul 2010, 22:34
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17287
Location: In your JS exploiting you and your system
revolution
b1528932 wrote:
what about stack? does 0 is a valid address for top of stack?
I think this Q should be added to the FAQ. Many people seem to ask this.

The answer is yes. And it is really easy to test for oneself if one wants to be sure.
Post 31 Jul 2010, 22:50
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