Re: [Bochs-developers] RE Bug in Bochs or my code?

[Hamoud M. <hm...@ma...>]

Hi,

I have good news; 

I have found the instruction that caused the problem in memory location
0x104d3

the instruction is : add byte ptr ds:[bx+si], al ; 0000

1000:04c3  lgdt [ds:0xc88]           ; 0f0116880c
1000:04c8  mov eax, cr0              ; 0f20c0
1000:04cb  or al, 0x1                ; 0c01
1000:04cd  mov cr0, eax              ; 0f22c0
1000:000004d0  mov ax, 0x10              ; b81000
1000:000004d3  add byte ptr ds:[bx+si], al ; 0000
1000:000004d5  mov ds, ax                ; 8ed8
1000:000004d7  mov es, ax                ; 8ec0

Registers:
eax            0x60000010       1610612752
ecx            0x0              0
edx            0xe0             224
ebx            0xffff           65535
esp            0xfffe           0xfffe
ebp            0x0              0x0
esi            0x510            1296
edi            0x500            1280
eip            0x4d5            0x4d5
eflags         0x7              7
cs             0x1000           4096
ss             0x9000           36864
ds             0x1000           4096
es             0x1000           4096
fs             0x0              0
gs             0x0              0

I suggest you to add some directives to set instructions size, if you are
using NASM try to add [bits 32] at the start of your asm file. I guess that before
switching to protected mode you must use 32 bit instructions.

Conclusions:
1-You have a problem in your code.
2- Bochs's debugger has a problem in "watch write address" command. It can't
detect all kinds of memory writes.

Thanks.


----- Original Message -----
Subject: [Bochs-developers] RE Bug in Bochs or my code?
Sent: Fri, 25 Feb 2005 19:45:08 +0100
From: Chris <cod...@ya...>
To: boc...@li...
> Yeah, I found the problem! When I´m setting the pmode bit and do not 
>jump the cpu seems to be in a 16bit pmode, right? So that an instruction 
>was wrongly decode and has overwritten this shit piece of code :(
>
>
>
>
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