2002-02-02 17:55:58

by Benny Sjostrand

[permalink] [raw]
Subject: 512 Mb DIMM not detected by the BIOS!

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



2002-02-02 18:16:52

by Kilobug

[permalink] [raw]
Subject: Re: 512 Mb DIMM not detected by the BIOS!

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 : [email protected] Work Mail : [email protected]
GSM : 06.71.47.18.22 (in France) ICQ UIN : 7299959
Fingerprint : 1F2C 9804 7505 79DF 95E6 7323 B66B F67B 7103 C5DA

"Software is like sex it's better when it's free.", Linus Torvalds

2002-02-02 21:26:09

by Daniel J Blueman

[permalink] [raw]
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.

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

2002-02-04 11:18:55

by Wojtek Pilorz

[permalink] [raw]
Subject: RE: 512 Mb DIMM not detected by the BIOS!

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

> Date: Sat, 2 Feb 2002 21:25:44 -0000
> From: Daniel J Blueman <[email protected]>
> To: 'Benny Sjostrand' <[email protected]>, [email protected]
> 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


2002-02-05 07:00:32

by Cliff Albert

[permalink] [raw]
Subject: Re: 512 Mb DIMM not detected by the BIOS!

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 | http://www.oisec.net
[email protected] | 6BONE: CA2-6BONE | icq 18461740

2002-02-06 16:22:19

by Bill Davidsen

[permalink] [raw]
Subject: Re: 512 Mb DIMM not detected by the BIOS!

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 <[email protected]>
CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.

2002-02-07 10:52:31

by Eric W. Biederman

[permalink] [raw]
Subject: Re: 512 Mb DIMM not detected by the BIOS!

"Daniel J Blueman" <[email protected]> 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