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From: Andrew Kirilenko <icedank@gmx.net>
To: linux-kernel@vger.kernel.org
Subject: Re: Stored data missed in setup.S
Date: Wed, 23 Apr 2003 17:50:50 +0300
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Hello!
>
> [SNIPPED...]
>
> > OK. And now code looks like:
> > -->
> > start_of_setup: # line 160
> > 	# bla bla bla - some checking code
> >         movb    $1, %al
> >         movb    %al, (0x100)
> > ....
> > ....
> > 	cmpb    $1, (0x100)
> > 	je bail820 # and it DON'T jump here
> > <--
> >
> >
> > I'm sure, I'm doing something wrong. But what???
>
> The only possibiity is that the code you just showed is not
> being executed. Absolute location 0x100 is not being overwritten
> by some timer-tick (normally) so whatever you write there should
> remain. You just put a byte of 1 in that location and then
> you compared against a byte of 1. If the CPU was broken, you
> wouldn't have even loaded your code.
>
> It is quite likely that the IP is being diverted around your code
> by some previous code.
>
> FYI, you can check the progress of your code by 'printing' on
> the screen. Set up ES to point to the screen segment, and write
> letters there:
>
> 	movw	$0xb800, %ax
> 	movb	%ax, %es
> 	movb	$'A', %es:(0)
>
> This 'prints' an 'A' at the first location on the screen.

Ha! I don't have video adapter not keyboard on that PC :)
And, when I change je to jmp it works perfectly.


Best regards,
Andrew.