512 Mb DIMM not detected by the BIOS!

512 Mb DIMM not detected by the BIOS!

[Benny Sjostrand]

Hello everyone!

I'm new to this mailinglist so please tellme if you think i'm "out of 
topoic".

I've have trouble with the following issue:
On two x86 machines, one AMD k62 and a Pentium the Bios dont wont to 
detect properly a 512 MB PC133 DIMM, the K62 based it dont detect it at 
all, and on the PII it detect it as a 128MB DIMM.
I suspect that's the BIOS that "sucks", not the HW, i supose that the HW 
is capable to deal with 512MB DIMM's, so my question to you 
"kernel-gurus", is there any posibility to configure the Linux kernel to 
bypass the BIOS and actually use my 512MB ?

Thanks!

/Benny

Re: 512 Mb DIMM not detected by the BIOS!

[Kilobug]

Benny Sjostrand wrote:
> Hello everyone!

Hello

> so my question to you "kernel-gurus", is there any posibility
 > to configure the Linux kernel to bypass the BIOS and actually
 > use my 512MB ?

You don't need to be a "kernel-guru" to answer this question.
The list of kernel boot parameters is in
linux/Documentation/kernel-parameters.txt
There, you can find:

  mem=nn[KMG]     [KNL,BOOT] force use of a specific amount of
                  memory; to be used when the kernel is not able
                  to see the whole system memory or for test.

So append mem=512M in your kernel command line. If you use lilo add
append = "mem=512M" in your lilo.conf file (and rerun lilo).

-- 
** Gael Le Mignot "Kilobug", Ing3 EPITA - http://kilobug.free.fr **
Home Mail   : kilobug@freesurf.fr          Work Mail : le-mig_g@epita.fr
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"Software is like sex it's better when it's free.", Linus Torvalds

RE: 512 Mb DIMM not detected by the BIOS!

[Daniel J Blueman]

Hey Benny,

This is a chipset problem. Chipsets support up to x CAS (column) lines
and y RAS (row) lines, and depending on your DIMM memory module layout
and configuration, you 512MB DIMM will be detected as a different sized
module.

Eg. The venerable Intel 440BX (PII) chipset supports a max of 256MB per
slot. Ah well.

Since it's a chipset (ie hardware) issue, it's not possible to work
around this problem - you need a newer chipset. Sorry.

Dan

____________________
Daniel J Blueman 

> I'm new to this mailinglist so please tellme if you think i'm "out of 
> topoic".
> 
> I've have trouble with the following issue:
> On two x86 machines, one AMD k62 and a Pentium the Bios dont wont to 
> detect properly a 512 MB PC133 DIMM, the K62 based it dont 
> detect it at 
> all, and on the PII it detect it as a 128MB DIMM.
> I suspect that's the BIOS that "sucks", not the HW, i supose 
> that the HW 
> is capable to deal with 512MB DIMM's, so my question to you 
> "kernel-gurus", is there any posibility to configure the 
> Linux kernel to 
> bypass the BIOS and actually use my 512MB ?
> 
> Thanks!
> 
> /Benny

RE: 512 Mb DIMM not detected by the BIOS!

[Wojtek Pilorz]

On Sat, 2 Feb 2002, Daniel J Blueman wrote:

> Date: Sat, 2 Feb 2002 21:25:44 -0000
> From: Daniel J Blueman <daniel.blueman@btinternet.com>
> To: 'Benny Sjostrand' <gorm@cucumelo.org>, linux-kernel@vger.kernel.org
> Subject: RE: 512 Mb DIMM not detected by the BIOS!
> 
> Hey Benny,
> 
> This is a chipset problem. Chipsets support up to x CAS (column) lines
> and y RAS (row) lines, and depending on your DIMM memory module layout
> and configuration, you 512MB DIMM will be detected as a different sized
> module.
> 
> Eg. The venerable Intel 440BX (PII) chipset supports a max of 256MB per
> slot. Ah well.
> 

I had similar problem - on an Intel 440BX based motherboard (ABIT BX-133
RAID) the 256MB DIMMs I originally got were only 'half-detected' (e.g. I
got only 128MB from each one); These DIMMs were working OK on some
VIA-based systems; after changing them to a different type (both old and
new were ECC DIMMs from Kingston, just different type) they are working
OK.

I it could be of any help, I can find the part numbers/names of my DIMMs.

> Since it's a chipset (ie hardware) issue, it's not possible to work
> around this problem - you need a newer chipset. Sorry.
Or maybe another DIMM type - at least I was able to successfully use 256MB
DIMMs of appropriate type.

I also don't think kernel tricks would not get back the lost memory here.

> 
> Dan
> 
> ____________________
> Daniel J Blueman 
> 
> > I'm new to this mailinglist so please tellme if you think i'm "out of 
> > topoic".
> > 
> > I've have trouble with the following issue:
> > On two x86 machines, one AMD k62 and a Pentium the Bios dont wont to 
> > detect properly a 512 MB PC133 DIMM, the K62 based it dont 
> > detect it at 
> > all, and on the PII it detect it as a 128MB DIMM.
> > I suspect that's the BIOS that "sucks", not the HW, i supose 
> > that the HW 
> > is capable to deal with 512MB DIMM's, so my question to you 
> > "kernel-gurus", is there any posibility to configure the 
> > Linux kernel to 
> > bypass the BIOS and actually use my 512MB ?
> > 
> > Thanks!
> > 
> > /Benny

Re: 512 Mb DIMM not detected by the BIOS!

[Cliff Albert]

On Mon, Feb 04, 2002 at 12:17:10PM +0100, Wojtek Pilorz wrote:

> > This is a chipset problem. Chipsets support up to x CAS (column) lines
> > and y RAS (row) lines, and depending on your DIMM memory module layout
> > and configuration, you 512MB DIMM will be detected as a different sized
> > module.
> > 
> > Eg. The venerable Intel 440BX (PII) chipset supports a max of 256MB per
> > slot. Ah well.
> > 
> 
> I had similar problem - on an Intel 440BX based motherboard (ABIT BX-133
> RAID) the 256MB DIMMs I originally got were only 'half-detected' (e.g. I
> got only 128MB from each one); These DIMMs were working OK on some
> VIA-based systems; after changing them to a different type (both old and
> new were ECC DIMMs from Kingston, just different type) they are working
> OK.
> 
> I it could be of any help, I can find the part numbers/names of my DIMMs.
> 
> > Since it's a chipset (ie hardware) issue, it's not possible to work
> > around this problem - you need a newer chipset. Sorry.
> Or maybe another DIMM type - at least I was able to successfully use 256MB
> DIMMs of appropriate type.

Double Sided 256MB Dimms are required, single sided dimms rarely work on
BX-based boards.

-- 
Cliff Albert		| RIPE:	     CA3348-RIPE | www.oisec.net
cliff@oisec.net		| 6BONE:     CA2-6BONE	 | icq 18461740

Re: 512 Mb DIMM not detected by the BIOS!

[Bill Davidsen]

On Tue, 5 Feb 2002, Cliff Albert wrote:

> On Mon, Feb 04, 2002 at 12:17:10PM +0100, Wojtek Pilorz wrote:

> > > Since it's a chipset (ie hardware) issue, it's not possible to work
> > > around this problem - you need a newer chipset. Sorry.
> > Or maybe another DIMM type - at least I was able to successfully use 256MB
> > DIMMs of appropriate type.
> 
> Double Sided 256MB Dimms are required, single sided dimms rarely work on
> BX-based boards.

  I have to agree that requiring the correct part for memory is not
usually considered a "hardware issue" as most people see it.

  I believe the VIA chipsets have similar features, the last m/b I
installed said it supported 4 DIMMs, up to 3GB. So a 1GB part will work,
but if you put in four only three operate (I didn't have four to try).

-- 
bill davidsen <davidsen@tmr.com>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.

Re: 512 Mb DIMM not detected by the BIOS!

[Eric W. Biederman]

"Daniel J Blueman" <daniel.blueman@btinternet.com> writes:

> Hey Benny,
> 
> This is a chipset problem. Chipsets support up to x CAS (column) lines
> and y RAS (row) lines, and depending on your DIMM memory module layout
> and configuration, you 512MB DIMM will be detected as a different sized
> module.
> 
> Eg. The venerable Intel 440BX (PII) chipset supports a max of 256MB per
> slot. Ah well.
> 
> Since it's a chipset (ie hardware) issue, it's not possible to work
> around this problem - you need a newer chipset. Sorry.

Additionally memory is generally and practically a setup once thing in
every chipset I have looked at.  Even if the chipsets supports it
would be very difficult ``fix'' this afterwards.

Eric