allocating low memory

allocating low memory

Post by John K. Peterso » Thu, 11 Apr 1996 04:00:00

I haven't given up on my crusade to get Linux working on the DOS card in my
Mac.  However, I've run into another snag.

The BIOS driver that I'm working with were written for 1.1.70.  In main.c it
uses 'low_memory_start' to allocate the code and buffer space for use when
switching to real mode.  However, 'low_memory_start' seems to have disappeared.
I've even looked through all the kernel changes from 1.1.70 on and found no
mention of it changing.

How does one allocate low (<1M) memory in 1.2.13?

Another question.  It uses gdt[6] and gdt[7] for the real-mode code and data
segments.  Is this going to cause a problem in the current versions of the
kernel.  The 'Hackers Guide' seems to suggest it might.


John Peterson -- University Networking Services -- Brigham Young University


1. Low-memory install: Cannot allocate memory at startup!

Argh!  So close!

I'm installing Debian because it is the only one I've seen that even talks
about machines with 4M of ram.
This is an old, Ascentia 800N laptop, 4M ram, something round 512M

Partitions are 300+M Linux native, 2M minix for temp install, and 82M+  for
Linux swap.

Using the Debian low-mem install.  All goes well until booting from the
harddrive.  I avoid installing any new modules.
Several messages appear during startup, exclaiming they cannot allocate
modprobe complains its out of memory
grep complains about memory cannot map zero-fill pages: cannot allocate memory

Argh!  Has anybody managed to pull this off?  Do you have any pointers?
I'll trade Shiner Bock for some good hints (srma)!


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