From: Martin Str|mberg <ams AT father DOT ludd DOT luth DOT se>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Pharlap 286
Date: Fri, 27 Jul 2001 11:46:28 +0000 (UTC)
Organization: University of Lulea, Sweden
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Charles Sandmann <sandmann AT clio DOT rice DOT edu> wrote:
: You must at a minimum watch 0x88 and 0xe801 but there are others.
: Scour RB's interrupt list and you'll find 1/2 dozen for the PC
: architecture, and then you also need to support PC98 (Asian) 
: which has different requirements.

What are those differences? I found a document pc98.pdf by searching
on www.google.com but it's not talking about XMS, extended memory or
INT15. Is this documented in RBIL?

: But this is a moot point, since there are lots of workarounds
: (like load himem.sys which allows dos=high, or emm386 which
: allows umbs and guaranteed to work).  In the 7 years versions of
: CWSDPMI have been out there, I can't recall a single complaint
: on this.  I'd much rather spend time supporting 2Gb memory
: machines (which are now very common with the cost of RAM).  If
: anyone is booting a machine "raw" it's typically for a single
: purpose - not general use (spawning obsolete subprograms).

I think you misunderstood why I'm asking. Or perhaps I didn't make it
clear. I'm hacking FDXMS.SYS adding memory detection using INT15
AX=0xe820 etc, so I'm interested in what I have to do to do (Hey, it
echoes here!) it properly.

:> How hard would it be to make CWSDPMI support 16-bit DPMI as well?

: In particular, the interrupt table format must change to be 16-bit
: interrupts instead of 32-bit interrupts (see Intel manual) for 
: hooking and chanining, exceptions must be 16-bit, etc.  This is
: why you can't have 16-bit and 32-bit DPMIs alive at the same
: time.  The DPMI 1.0 fix for this would be to have separate IDTs
: for each client (a whole new can of worms).

Can't this be solved by having 32-bit version and somehow detect that
it's a 16-bit application making the interrupt and then massage the
arguments?

:> How hard would it be to make CWSDPMI active from start and map in some
:> pages at 0xc0000 - 0xdffff (an EMM386 UMB replacement)?

: Currently CWSDPMI turns off paging when swapping back to real mode,
: but maybe that could be changed (can't remember details).  Then you 

If CWSDPMI switched to V86 mode instead of real mode this would not be
a problem.


Right,

						MartinS