only part of RAM recognized

only part of RAM recognized

Post by Thomas Rueda » Fri, 03 Aug 2001 08:21:12



Hello,
a few days ago I noticed a problem with the RAM of my PC, wondering why
it suddenly was *that* slow. At the beginning of the boot process, the
usual memory scan correctly detects 40960 KB, but after booting Linux, I
only get
Memory: 13096k/15360k available (1124k kernel code, 384k reserved, 756k
data),
and this is also what top displays resp. what I read in /proc/meminfo.
The RAM is 2x16M+2x4M, which is supported by the board according to the
manufacturer's specs, and the system is a P100 running 2.0.34 (Debian).
The last memory upgrade was ca. 3 years ago.
Any ideas how to make Linux recognize the rest of the RAM again?
--
------------------------------------------------------------------------
Thomas Ruedas
Institute of Meteorology and Geophysics, J.W.Goethe University Frankfurt

http://www.geophysik.uni-frankfurt.de/~ruedas/
------------------------------------------------------------------------
 
 
 

only part of RAM recognized

Post by Bob Marti » Fri, 03 Aug 2001 09:08:23



> Hello,
> a few days ago I noticed a problem with the RAM of my PC, wondering why
> it suddenly was *that* slow. At the beginning of the boot process, the
> usual memory scan correctly detects 40960 KB, but after booting Linux, I
> only get
> Memory: 13096k/15360k available (1124k kernel code, 384k reserved, 756k
> data),
> and this is also what top displays resp. what I read in /proc/meminfo.
> The RAM is 2x16M+2x4M, which is supported by the board according to the
> manufacturer's specs, and the system is a P100 running 2.0.34 (Debian).
> The last memory upgrade was ca. 3 years ago.
> Any ideas how to make Linux recognize the rest of the RAM again?
> --

Check your BIOS settings, sounds like you have the memory hole option enabled
which usually is around 16mb by default. Turn it off if it enabled.
--

Bob Martin

 
 
 

only part of RAM recognized

Post by Aleksey Cheuso » Fri, 03 Aug 2001 18:54:50



> Hello,
> a few days ago I noticed a problem with the RAM of my PC, wondering why
> it suddenly was *that* slow. At the beginning of the boot process, the
> usual memory scan correctly detects 40960 KB, but after booting Linux, I
> only get
> Memory: 13096k/15360k available (1124k kernel code, 384k reserved, 756k
> data),
> and this is also what top displays resp. what I read in /proc/meminfo.
> The RAM is 2x16M+2x4M, which is supported by the board according to the
> manufacturer's specs, and the system is a P100 running 2.0.34 (Debian).
> The last memory upgrade was ca. 3 years ago.
> Any ideas how to make Linux recognize the rest of the RAM again?

Try to add to the following line to lilo.conf

append="mem=40M"

Also see

man bootparam
BootPrompt-HOWTO

 
 
 

only part of RAM recognized

Post by Thomas Rueda » Fri, 03 Aug 2001 21:57:49


Quote:>Try to add to the following line to lilo.conf
>append="mem=40M"

I thought that should not be necessary with such a small amount of RAM?
Anyway, I'll do try it ASAP (my box is at home).
--
------------------------------------------------------------------------
Thomas Ruedas
Institute of Meteorology and Geophysics, J.W.Goethe University Frankfurt

http://www.geophysik.uni-frankfurt.de/~ruedas/
------------------------------------------------------------------------
 
 
 

only part of RAM recognized

Post by Thomas Rueda » Fri, 03 Aug 2001 21:54:36


Quote:>Check your BIOS settings, sounds like you have the memory hole option enabled
>which usually is around 16mb by default. Turn it off if it enabled.

My BIOS seems to be rather primitive (it's a 6 year-old AMIBIOS), I
didn't discover something about the memory hole option there; I saw such
a menu item in newer machines, but never on mine. So: no progress.
--
------------------------------------------------------------------------
Thomas Ruedas
Institute of Meteorology and Geophysics, J.W.Goethe University Frankfurt

http://www.geophysik.uni-frankfurt.de/~ruedas/
------------------------------------------------------------------------
 
 
 

only part of RAM recognized

Post by Michael Lee Yoh » Sat, 04 Aug 2001 06:05:39


Quote:>>append="mem=40M"

> I thought that should not be necessary with such a small amount of
> RAM? Anyway, I'll do try it ASAP (my box is at home).

Yes, theoretically it _is_ unnecessary.  However, if your BIOS is
ignoring the correct amount of memory, you can force the kernel into
accepting that there is _X_MB of memory installed.

Of the obvious, have you swapped the modules (1/2 with 3/4) to see if
the banks are functioning properly?

--


Software Developer, Engineering Services
Red Hat, Inc.

 
 
 

only part of RAM recognized

Post by Thomas Rueda » Sat, 04 Aug 2001 23:11:49


Quote:>append="mem=40M"

I've tried out this one now, and it does boot and recognize all of the
memory - but when I start the fvwm, it hangs, and there is no other way
out than pressing the reset button, because even Ctrl+Alt+Backspace does
not react. Reducing mem to, say, mem=38M did not solve it.
I didn't have time to swap the modules yet, but anyway: I have 2 4M
EDORAM and 2 16M Fast Page modules. According to the board manual, this
combination is allowed in both possible configurations. Although I don't
remember anymore if I left the old 4M modules on Bank 0 or shifted them
to Bank 1 when I added the 16M modules later, I wonder why the odd
amount of 15M was recognized in the old settings. Are there known
problems with different kinds of RAM modules?

BTW, we experienced the problem with setting the append mem string to
the nominal amount of memory on another computer here as well (different
board, different distribution, everything newer): although 128M had been
inserted and were specified in the lilo.conf, the machine would hang
during booting until we lowered the amount by 4M or so.
--
------------------------------------------------------------------------
Thomas Ruedas
Institute of Meteorology and Geophysics, J.W.Goethe University Frankfurt

http://www.geophysik.uni-frankfurt.de/~ruedas/
------------------------------------------------------------------------

 
 
 

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