From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from www.linux.org.uk (parcelfarce.linux.theplanet.co.uk [195.92.249.252]) by dsl2.external.hp.com (Postfix) with ESMTP id 8AB8E4868 for ; Fri, 20 Feb 2004 11:22:01 -0700 (MST) Received: from willy by www.linux.org.uk with local (Exim 4.22) id 1AuFHQ-0004iG-9n; Fri, 20 Feb 2004 18:21:40 +0000 Date: Fri, 20 Feb 2004 18:21:40 +0000 From: Matthew Wilcox To: Joel Soete Subject: Re: [parisc-linux] Linux only see 2Gb of ram of N4k Message-ID: <20040220182140.GC11824@parcelfarce.linux.theplanet.co.uk> References: <402A4CA500006EA3@ocpmta2.freegates.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <402A4CA500006EA3@ocpmta2.freegates.net> Sender: Cc: parisc-linux@lists.parisc-linux.org List-Id: parisc-linux developers list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Feb 20, 2004 at 07:04:26PM +0100, Joel Soete wrote: > Hi all, > > My collegue make me notice that the N4k on which I can test Linux was supplied > with 4Gb of ram (which if confirm at boot prompt) but Linux only see 2Gb. > > It is a dual cpu machine, is that 1/2 ram dedicated to 1 cpu and the other > 1/2 to the 2d cpu? Unlikely. As I recall, the N4k diagram looks like this: <-PCI-> Elroy <-Ropes\ PA <-+-> PA PA <-+-> PA /Ropes-> Elroy <-PCI-> Elroy <-Ropes-\ DEW RAM DEW /-Ropes-> Elroy <-PCI-> Elroy <-Ropes--> IKE <-Merced-> Stretch <-Merced-> IKE <--Ropes-> Elroy <-PCI-> Elroy <-Ropes-/ DEW RAM DEW \-Ropes-> Elroy <-PCI-> Elroy <-Ropes/ PA <-+-> PA PA <-+-> PA \Ropes-> Elroy So the RAM is uniformly-accessible from all CPUs, but the IO is not. If you look at pat_memconfig() in arch/parisc/kernel/inventory.c, you'll see how we try to figure out what memory ranges are in the machine. Want to try debugging that, see what's being reported by firmware? -- "Next the statesmen will invent cheap lies, putting the blame upon the nation that is attacked, and every man will be glad of those conscience-soothing falsities, and will diligently study them, and refuse to examine any refutations of them; and thus he will by and by convince himself that the war is just, and will thank God for the better sleep he enjoys after this process of grotesque self-deception." -- Mark Twain