Re: [parisc-linux] Linux only see 2Gb of ram of N4k

[Matthew Wilcox <willy@debian.org>]

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?

-- 
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