Date: Wed, 2 Apr 1997 19:18:20 +0300 (IDT)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Peter Berdeklis <peter AT atmosp DOT physics DOT utoronto DOT ca>
cc: djgpp AT delorie DOT com
Subject: Re: Interrupt handlers and page locking 
In-Reply-To: <Pine.SGI.3.91.970402110747.1182A-100000@atmosp.physics.utoronto.ca>
Message-ID: <Pine.SUN.3.91.970402191322.24503I-100000@is>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII


On Wed, 2 Apr 1997, Peter Berdeklis wrote:

> Also if you use a memory manager like QEMM you can load many of 
> your TSRs into extended memory with the loader (LOADHI for QEMM).

No.  QEMM indeed takes the memory from the extended RAM, but it remaps it
to the addresses below 1MB using the memory-mapping feature of the V86
mode.  Real-mode DOS cannot access addresses above 1MB directly (by
dereferencing a pointer), so this remapping must be done for the TSRs to
work at all.  And addresses below 1MB aren't used by DJGPP unless the
amount of free memory above 1MB is less than 256K. 

Of course, if the TSR uses extended memory, like SmartDrv does, it will 
make less RAM available to DJGPP programs.

> I still think that the best way is to pop out some of your RAM - although 
> these days with 16MB SIMMs you still need to waste some memory.

A much easier way is to spawn the tested program from another DJGPP 
program which calloc's a lot of RAM before it spawns the child.