Mail Archives: djgpp/1997/03/14/10:16:29
Paul Derbyshire (ao950 AT FreeNet DOT Carleton DOT CA) wrote:
: Steven Burrows (steve AT poota DOT dungeon DOT com) writes:
: > Folks,
: >
: > I have a problem with RHIDE under MS-Windows. When I select Build All
: > from the compile menu RHIDE terminates. It works OK if I use Compile, or
: > Link, it is just Build All that gives me a problem.
: >
: > I think this must be a problem with my MS-Windows or dosprmpt.pif
: > configuration - any suggestions?
: I'm not sure. When I use RHIDE in Windows 95, I can't compile, only work
: on source, but I have isolated it as memory problems. For some reason
: RHIDE and other DJGPP progs only seem to use one meg of disk space for
: swap in Windows, even though I have seventy meg free with and without
: windows on that drive. (The Windows swap file is permanent, 20 meg, and on
: the other hard drive, so it isn't eating up the disk space for DJGPP's
: swap.)
You misunderstand the way this works; your virtual memory is provided by
Windows, and comes from the physical memory and the Windows swap file.
Windows is a fairly antisocial DPMI host; it is reluctant to give you more
virtual memory than half of the physical, I think (not sure exactly). This
explains why you're not getting much RAM for your programs.
: As a result I only have 5-6 megs available. Ironically, I only need
: seven or eight since I rarely get swap activity in DOS compiling in RHIDE,
: where I have all physical RAM (8 meg) free.
: In any case, my symptoms are: compile from RHIDE, it just says in the
: message windows
: Compiling blahblah.c
: There were some errors
: without any message of what the errors are (whether this is a bug in RHIDE
: or a bug in GCC I don't know).
This is definitely a low-memory error; under dosemu, before I altered my
configuration, I only had about 4Mb (maybe less) available and again RHIDE
wouldn't compile.
: If I shell to DOS from RHIDE and gcc, or
: gxx, I get Load error: no DPMI memory. Strange given there are about six
: megs of DPMI memory, less RHIDE's 300K, which should actually be paged
: entirely to disk during a shell(!), and the 40K max of source code in
: editors (which should also be paged...a DJGPP app does page out its stack
: and heap as well as code entirely, when shelling, doesn't it?)
You shouldn't really make assumptions about what goes on behind the
scenes. It is entirely up to Windows what it does to your memory and when;
if it decides to leave RHIDE in physical RAM and run your gcc session from
the hard disk, there's nothing you can do about it (apart from recompile
gcc requesting that it be locked in physical memory, but this may still
fail, particularly if you don't have enough RAM). So a DJGPP app doesn't
page anything - Windows, in this case, is doing that.
: If I gcc from a DOS prompt without RHIDE it works fine, and I never have
: trouble with Windows not resident.
That's using CWSDPMI as DPMI host, rather than Windows, and CWSDPMI (as
documented) gives you up to 256Mb of memory, split 128-128 between real
and virtual.
--
George Foot <mert0407 AT sable DOT ox DOT ac DOT uk>
Merton College, Oxford
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