flat assembler
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b1528932



Joined: 21 May 2010
Posts: 287
b1528932
i have a problem, using this sequence:
Code:
out 0,al
in al,0
out 0,ax
in ax,0
out 0,eax
in eax,0
out -1,al
in al,-1
out -1,ax
in ax,-1
out -1,eax
in eax,-1
jmp $    

goes right through jmp $

CR0.PE = 1
EFER.LME = 0
IOPL = 0
TR = 0
CPL = 3

in/out are privileged instruction, and they should generate exception with vector D. yet they execute, why? bochs even output me some i/o related messages. but all it should do is throw exception.
Post 23 Jun 2010, 19:48
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
I have not much experience with this so it may not be the exact problem, but have you checked how are you supposed to set-up the I/O permission bitmap in the TSS?
Post 23 Jun 2010, 20:21
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b1528932



Joined: 21 May 2010
Posts: 287
b1528932
i never tested it yet, but i think i know how.
iopb is starting offset of map, TSS limit is the end. if i use map, i must make sure that number of its bytes is *2, because cpu read 2 bytes at once. last byte must be 0xFF.

i have Task Register = 0, so TSS is not used at all.

io bitmap has nothing to do with it.
Post 23 Jun 2010, 21:12
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