BUG: USEDPMI crashes inside BOCHS // please test

Index > DOS > BUG: USEDPMI crashes inside BOCHS // please test

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DOS386

Joined: 08 Dec 2006
Posts: 1904

DOS386 16 Apr 2007, 00:14

Seems that the USEDPMI example provided in the FASM DOS package
mostly crashes inside BOCHS. Crying or Very sad

Never got such a crash on real PC or in QEMU.

Under HDPMI32 there is always PageF, with CWSDPMI: GPF or PageF, EIP 0 ... 5 Crying or Very sad

Seems to occur after the second mode switch. Any ideas what's wrong ?
Is the example faulty or did I find a bug in BOCHS Confused

?

Have to add that the BUG seems to be specific for FASM's USEDPMI, I never
got such a bug with executables from DGJPP (incl. FB (works), ignoring FP (too faulty by itself Crying or Very sad

) ) or DOS/32A extender.

_________________
Bug Nr.: 12345

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

Status: Closed: NOT a Bug

Last edited by DOS386 on 30 Jun 2007, 20:51; edited 2 times in total

16 Apr 2007, 00:14

Hayden

Joined: 06 Oct 2005
Posts: 132

Hayden 16 Apr 2007, 03:58

CWDPMI - is this the Causeway Extender by Micheal Divoure

of so then one can use the environment strings ->

SET CAUSEWAY=SWAP:path --> specify swapfile path

or...

SET CAUSEWAY=NOVM --> disable dos swapfile

thought this may help Smile

_________________
New User.. Hayden McKay.

16 Apr 2007, 03:58

DOS386

Joined: 08 Dec 2006
Posts: 1904

DOS386 27 Apr 2007, 07:21

Quote:

thought this may help

SORRY it doesn't Sad

Quote:

CWDPMI - is this the Causeway Extender by Micheal Divoure

No.

Have you a TEXT-only-Browser maybe - don't see the shot ?

Causeway DOS Extender by Michael Devore
CWSDPMI by C.W. Sandman

Anyone tested the USEDPMI inside BOCHS or has an idea ?

27 Apr 2007, 07:21

Hayden

Joined: 06 Oct 2005
Posts: 132

Hayden 27 Apr 2007, 18:05

In bochs I need to have the causeway extender set to disable pagefile else crash when useing floppy.

sorry about miss-understood

_________________
New User.. Hayden McKay.

27 Apr 2007, 18:05

DOS386

Joined: 08 Dec 2006
Posts: 1904

DOS386 17 Jun 2007, 23:41

No ideas ? Crying or Very sad

17 Jun 2007, 23:41

bttr

Joined: 21 Oct 2003
Posts: 16
Location: Berlin, Germany

bttr 19 Jun 2007, 16:24

1) put "magic_break: enabled=1" to your Bochs config file
2) start `bochsdbg.exe'
3) put "xchg bx,bx" to `Usedpmi.asm', assemble
4) start `usedpmi.exe' and step through

19 Jun 2007, 16:24

rugxulo

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

rugxulo 24 Jun 2007, 23:06

Anybody know of an easy way (in assembly) to detect if BOCHS is running?

24 Jun 2007, 23:06

DOS386

Joined: 08 Dec 2006
Posts: 1904

DOS386 24 Jun 2007, 23:28

To bttr : thanks

http://bochs.sourceforge.net/doc/docbook/user/bochsrc.html#AEN1928

Quote:

Anybody know of an easy way (in assembly) to detect if BOCHS is running?

Unreproductable: if BOCHS is running or whether running inside BOCHS ? Confused

YES !!! The USEDPMI code - if it crashes, you are inside BOCHS !!! Laughing

Could you test it please ?

Other ideas:

CPUID & measure frequency, if high-end CPU with incredibly low performance, you are inside BOCHS Laughing

Look into the BIOS

Check the VESA

24 Jun 2007, 23:28

rugxulo

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

rugxulo 12 Jul 2007, 19:34

That request was mainly for Eric Auer (FreeDOS), and he ended up going with VESA 2.0 OEM string (check for "BOCH") for FDAPM, so thanks! Wink

12 Jul 2007, 19:34

Japheth

Joined: 26 Oct 2004
Posts: 151

Japheth 19 Jul 2007, 05:45

seems to be a bug in Bochs. Apparently it doesn't like EIP to be 00000000 if CS is 32bit. If you place a NOP before "start:", it works.

hint: debugx.com can be used to debug this app in Bochs. It shows that Bochs gets confused when emulating the "mov esi, 00000018" opcode at eip=0.

19 Jul 2007, 05:45

DOS386

Joined: 08 Dec 2006
Posts: 1904

DOS386 22 Jul 2007, 21:01

Thanks. BOCHS is BUGGY and I have the luck to find all those bugs Shocked

there ...

22 Jul 2007, 21:01

f0dder

Joined: 19 Feb 2004
Posts: 3174
Location: Denmark

f0dder 22 Jul 2007, 21:05

bochsy

- but what can you expect, it's a pretty complicated piece of software. Wonder if QEMU's a lot better in that regard.

22 Jul 2007, 21:05

DOS386

Joined: 08 Dec 2006
Posts: 1904

DOS386 24 Jul 2007, 06:19

> it's a pretty complicated piece of software.

YES.

> Wonder if QEMU's a lot better in that regard.

It does NOT have this bug (and there are at least 2 more bugs BOCHS has/used to have and QEMU doesn't/didn't have) ...

> an easy way (in assembly) to detect if BOCHS

One more:

http://bos.asmhackers.net/forum/viewtopic.php?id=59

No QEMU test Sad

Untested - abuse at your own risk Laughing

24 Jul 2007, 06:19

SFeLi

Joined: 03 Nov 2004
Posts: 138

SFeLi 17 Aug 2007, 00:01

Offtopic

Description:	Console Output & Debugger Break for Bochs	Download
Filename:	Console Output & Debugger Break for Bochs.zip
Filesize:	1.07 KB
Downloaded:	664 Time(s)

17 Aug 2007, 00:01

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