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From:	"Rod Pemberton" <do_not_have AT notemailnotq DOT cpm>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Mmap() and modify_ldt() in DOS
Date:	Mon, 11 Mar 2013 04:27:17 -0400
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"Napoleon80386" <napoleon80386 AT gmail DOT com> wrote in message
news:858e8912-407b-4b7b-843a-8dff31d35068 AT googlegroups DOT com...

> I guess that problem is mmap() and modify_ldt(), [...]
> They wrote that it is nesessary to implement mmap() and ldt.

I don't know whether implementing mmap() for DJGPP is easy or
difficult.  Whether mmap() is actually necessary or not for
porting WINE to DOS depends on what they used mmap() to do.
Robert Riebisch and I both came up with solutions to replace
mmap() in DOS port's of the dmidecode application.  However,
dmidecode didn't use most of mmap()'s functionality.

I do know that I replaced the use of mmap() in a personal port of
the dmidecode application's memory allocation routine with
compiler specific code for both DJGPP and OpenWatcom.  I did that
using nearptr's for DJGPP.  The DJGPP routine used malloc(),
memcpy(), __dpmi_get_segment_base_address(), _my_cs(), and
__djgpp_nearptr_enable().  OpenWatcom just needed malloc() and
memcpy().

As mentioned in the post to your friend, Robert Riebisch also came
up with a different solution for dmidecode.  Robert created a
filesystem for DJGPP called "/dev/mem".  That should allow you to
open, read, write, or close memory as if it's a regular text or
binary file.  In general, I'd think that functionality is about
the closest thing to mmap() for DJGPP.  His solution is in his
port of dmidecode on his webpage.  The link is in the other post.
Of course, Robert's "dev/mem" is a DJGPP only solution.  It won't
work with EMX.

So, you might first determine what they use mmap() to do.  Are
they using an mmap() only feature or not?  Or, can the
functionality be replaced with standard C functions?  Or, can
compiler specific C functions replace the use of mmap()?


Rod Pemberton

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