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 how to know if i'm in proteced or in real mode 
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Joined: Mon Feb 08, 2010 12:20 pm
Posts: 12
Post how to know if i'm in proteced or in real mode
I wanted to ask how to know (with what kind of code) if right now my bootloader has loaded in real mode or protected mode? For example, I want to print out A, if I'm already in proteced mode. Can anyone give me a code example or maybe theres another method with whom I can get the desired effect.


Sat Mar 06, 2010 8:34 am
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Joined: Sat Jul 25, 2009 7:44 am
Posts: 274
Location: United Kingdom
Post Re: how to know if i'm in proteced or in real mode
I wont give code, but using ASM or C, you can check for the relevant 1 Bit flag in CR0.

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Kieran C G Foot


Sat Mar 06, 2010 10:02 am
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Joined: Thu Jan 07, 2010 4:46 am
Posts: 5
Post Re: how to know if i'm in proteced or in real mode
But you must make sure that the code is the same both in 16 and 32 bit mode. ;)


Sun Mar 07, 2010 4:23 pm
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Joined: Wed Feb 10, 2010 6:32 am
Posts: 26
Post Re: how to know if i'm in proteced or in real mode
isn't it simply

cr0 % 2 == 0 => real mode else protected mode?

or am I wrong here? :D


Sat Mar 13, 2010 6:56 am
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