Re: Memory

[Ron Johnson <ron.l.johnson@cox.net>]

On Wed, 2003-09-03 at 11:05, Gary Hennigan wrote:
> Eicke <eick.jac@terra.com.br> writes:
> > I have a machine with 6Gb of memory. I installed the last version of Debian
> > and linux kernel 2.4.21.
> > I am trying to run the cap3 (ELF 32-bit LSB executable, Intel 80386, version
> > 1 (SYSV), dynamically linked (uses shared libs), not stripped), but the
> > following error occurs:
> > Ran out of memory: -874931512 bytes requested
> > I monitored and when the software reach 1.9 Gb the error occours.
> > Then I test another application all_align.pl (perl script text executable),
> > and when the script reach 3.0 Gb the following error occours:
> > out of memory
> >
> > In the first case I think is a software problem but in the second I guess
> > there is something in Operating System or Kernel configuration. I ran as
> > root and as common user in both cases.
> 
> In general you're not going to be able to allocate more than 2GB of
> RAM on a 32-bit system like the Pentium. While Intel played some
> tricks with the hardware and actually implemented a 36-bit address bus
> (I think it's 36 bits anyway), applications generally use 32-bit
> pointers on a 32-bit CPU and they're assumed to be signed so that
> limits you to 2^31 bytes of memory, or 2048MB (2GB). What the 6GB of
> RAM buys you is that you could run 3 separate processes each using 2GB
> of RAM and never hit your swap space, but a single application can't
> use more than 2GB at a time, in general.
> 
> There may be low-level things in the kernel that would allow you to
> use more than 2GB of RAM, but I'm not familiar with them and it
> certainly wouldn't be portable.
> 
> If you need an application to have access to more than 2GB of RAM then
> you need to get a 64-bit system like an Alpha, Sparc or Itanium.

I get the impression, though, that these are existing apps, that
only broke after upgrade to .21.

-- 
-----------------------------------------------------------------
Ron Johnson, Jr. ron.l.johnson@cox.net
Jefferson, LA USA

"Knowledge should be free for all."
Harcourt Fenton Mudd, Star Trek:TOS, "I, Mudd"