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

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DOS386



Joined: 08 Dec 2006
Posts: 1901
DOS386
Image

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
Post 16 Apr 2007, 00:14
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Hayden



Joined: 06 Oct 2005
Posts: 132
Hayden
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

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New User.. Hayden McKay.
Post 16 Apr 2007, 03:58
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DOS386



Joined: 08 Dec 2006
Posts: 1901
DOS386
Quote:
thought this may help


SORRY it doesn't Sad

Quote:
CWDPMI - is this the Causeway Extender by Micheal Divoure


No. Sad 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 ?
Post 27 Apr 2007, 07:21
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Hayden



Joined: 06 Oct 2005
Posts: 132
Hayden
In bochs I need to have the causeway extender set to disable pagefile else crash when useing floppy.

sorry about miss-understood

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New User.. Hayden McKay.
Post 27 Apr 2007, 18:05
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DOS386



Joined: 08 Dec 2006
Posts: 1901
DOS386
No ideas ? Crying or Very sad
Post 17 Jun 2007, 23:41
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bttr



Joined: 21 Oct 2003
Posts: 16
Location: Berlin, Germany
bttr
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
Post 19 Jun 2007, 16:24
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rugxulo



Joined: 09 Aug 2005
Posts: 2341
Location: Usono (aka, USA)
rugxulo
Anybody know of an easy way (in assembly) to detect if BOCHS is running?
Post 24 Jun 2007, 23:06
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DOS386



Joined: 08 Dec 2006
Posts: 1901
DOS386
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
Post 24 Jun 2007, 23:28
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rugxulo



Joined: 09 Aug 2005
Posts: 2341
Location: Usono (aka, USA)
rugxulo
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
Post 12 Jul 2007, 19:34
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Japheth



Joined: 26 Oct 2004
Posts: 151
Japheth
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.
Post 19 Jul 2007, 05:45
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DOS386



Joined: 08 Dec 2006
Posts: 1901
DOS386
Thanks. BOCHS is BUGGY and I have the luck to find all those bugs Shocked there ...
Post 22 Jul 2007, 21:01
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f0dder



Joined: 19 Feb 2004
Posts: 3170
Location: Denmark
f0dder
bochsy Smile - but what can you expect, it's a pretty complicated piece of software. Wonder if QEMU's a lot better in that regard.
Post 22 Jul 2007, 21:05
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DOS386



Joined: 08 Dec 2006
Posts: 1901
DOS386
> 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
Post 24 Jul 2007, 06:19
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SFeLi



Joined: 03 Nov 2004
Posts: 140
SFeLi
Offtopic


Description: Console Output & Debugger Break for Bochs
Download
Filename: Console Output & Debugger Break for Bochs.zip
Filesize: 1.07 KB
Downloaded: 206 Time(s)

Post 17 Aug 2007, 00:01
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