[comp.os.minix] Minix 1.5 Memory Allocation Question

joeg@starfish.Convergent.COM (Joe Gervais) (02/09/91)

Having just obtained a copy of PH Minix 1.5 and installed it on my 386 clone,
I have a question about memory allocation.  The answer is buried in the 
source code, but I haven't gotten that far yet.  I have 4MB of ram on the
system, 2MB which is page mode 32 bit memory, and the other 2MB is nibble mode
16 bit memory (couldn't justify $1000 for the proprietary 4MB expansion board,
but could justify the $100 for a couple of 1MB AT memory boards.

How is the memory allocation done in 1.5?

4MB      2MB Ram Disk             Program Space
             |                         |
3MB          |                         |
             |                         -
2MB          -                         |
             |                    Ram Disk      
1MB      Program Space                 |
            _|_                       _|_
0MB      Kernel                   Kernel

	 Option A                 Option B

I would hope that the memory allocation is like option A where the ram disk is 
in high memory, using up the slow 16 bit memory, but still considerably faster
than a rotating disk, and the kernel and program space fill lower memory first.
If memory allocation is indeed like option B, where the ram disk occupies the 
memory immediately following the kernel, is there a quick hack to place the 
ram disk in high memory.

P.S.  I bought The Book and Minix 1.0 several years ago, followed by 1.3, and
the 1.5 release was the first one that I could load onto my hard disk and run
with no unusual effort.  Thanks to ast and everyone else involved who have made
this possible.

Joe Gervais
joeg@convergent.com