4 GB RAM showing up as 3, BIOS memory hole and all that

Martin Cracauer cracauer at cons.org
Thu Sep 1 06:49:06 PDT 2005

Martin Cracauer wrote on Mon, Aug 15, 2005 at 12:56:57PM -0400: 
> Somebody here must know this:
> I have a Dual Opteron board with 4x 1 GB RAM.  The memory count in the
> BIOS goes up to 640 KB + 3072 MB, and FreeBSD says it sees 3 GB.

For what it's worth, I have my top gigabyte back.

I updated the BIOS and after fatfingering the update and getting a new
BIOS chip from Arima (overnighted for free with no questions asked,
great service!) I now see all 4 GB minus the AGP area of 128-256MB.

So cutting off all of the top gigabyte was indeed a BIOS problem.

The old BIOS also misconfigued something about my RAM which had slowed
it down severely.  The new BIOS makes the board a pretty fast one
considering I only have PC2100 memory.

As always, dmesg, pciconf, mptable etc is on

So just as advice for people having the problem: this is an area where
initial BIOSes often seems to be overly challenged.

Martin Cracauer <cracauer at cons.org>   http://www.cons.org/cracauer/
 No warranty.    This email is probably produced by one of my cats 
 stepping on the keys. No, I don't have an infinite number of cats.

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