Ultimate Debugger 2.0

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What instruction do you consider as most important ?

ud2

[ 1 ]

nop

21%

[ 3 ]

hlt

[ 1 ]

cpuid

[ 1 ]

mov

28%

[ 4 ]

xor

14%

[ 2 ]

lea

[ 0 ]

"private" (<- do NOT vote for this :-D)

14%

[ 2 ]

~~~ other

[ 0 ]

Total Votes : 14

Author

Thread

DOS386

Joined: 08 Dec 2006
Posts: 1904

DOS386 25 Dec 2006, 23:26

Code:

    push    cs
    pop     ds

    mov ax,1687h
    int 2Fh
    or  ax,ax           ; DPMI installed?
    jnz error
    test    bl,1            ; 32-bit programs supported?
    jz  error
    mov word [mode_switch],di
    mov word [mode_switch+2],es
    mov bx,si           ; allocate memory for DPMI data
    mov ah,48h
    int 21h
    jc  error
    mov es,ax
    mov ax,1
    call    far [mode_switch]   ; switch to PM, hoping it will keep long time 
    jc  error

    ud2           ; <- BOOM  !!!
    mov cx,1
    xor ax,ax
    int 31h         ; allocate descriptor for code

OK, this is NOT the first thread discussing this issue:

http://board.flatassembler.net/topic.php?t=4069 Wink

Nevertheless, I think I found a great debugging instrument.

But can someone explain me all the debug info provided by HDPMI32 ?
One can probably extract much more info than I understand by now.

1. Obvious
2. Obvious
3. Looks interesting. CS<>DS - required by PM ? Were unified before. Confused

What are the numbers in brackets ? Linear address of segment start ?
What else ?
4. What's this ? Interesting for me ?
5. This ? What do the "****" mean ?
6. Interesting for me ? Or only for debugging HDPMI32 itself ?
7. Interesting for me ? Or only for debugging HDPMI32 itself ?
8. How to use those numbers ?
9. Large collection. How to use ?

Please log IN to see the shot Wink

Description:	Crash screenshot
Filesize:	6.22 KB
Viewed:	4653 Time(s)

_________________
Bug Nr.: 12345

Title: Hello World program compiles to 100 KB !!!

Status: Closed: NOT a Bug

25 Dec 2006, 23:26

vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7103
Location: Slovakia

vid 26 Dec 2006, 00:39

see intel manuals. You just NEED them to understand this kind of stuff.

also, surely not "mov". on CISC x86 it is not THAT important. you can do pretty lot without it.

26 Dec 2006, 00:39

Goplat

Joined: 15 Sep 2006
Posts: 181

Goplat 26 Dec 2006, 01:16

I voted for HLT as most important. UD2, NOP, MOV, XOR and LEA all just have effects that can all be emulated using other instructions, and CPUID is convenient but not necessary (hey, people did without it for over a decade). But HLT is irreplaceable. No other instruction will save you money on your electric bill.

26 Dec 2006, 01:16

rugxulo

Joined: 09 Aug 2005
Posts: 2341
Location: Usono (aka, USA)

rugxulo 26 Dec 2006, 05:05

j[a-z]+ (jmp, jae, jb)
call/ret
push/pop
int3 (0xCC)

26 Dec 2006, 05:05

MCD

Joined: 21 Aug 2004
Posts: 602
Location: Germany

MCD 08 Jan 2007, 21:24

I voted for CPUID, which is very important to retrieve infos about newer features which cannot(at least not in user-mode) be retrieved otherwise

08 Jan 2007, 21:24

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