Re: 2.6.11 kernel can't see 4GB?

[Max <relf@unn.ac.ru>]

Koen,

What is the model of your motherboard?
Does it work stable after remapping?
Did you try to run application(s) that would use all 4GB of available memory (the simplest test is copying dvd image or a file of comparable size so it becomes cached into memory)?

On my Tyan Tiger K8W, PCI region remapping while making 4GB of memory available causes kernel traps on attepmts to use higher memory regions. So I'm forced to disable it in favor of system stability.

Max

Koen Tavernier wrote:
> Lennart Sorensen wrote:
>
> > On Tue, May 17, 2005 at 01:35:28PM +0100, Koen Tavernier wrote:
> >  
> >
> > > I've been running a dual opteron box with 2GB for a few days. Today I 
> > > added 2GB to the box, all recognised by the motherboard, but after 
> > > booting into linux (with the stock 2.6.11 debian kernel) free only 
> > > reports 3344996 Kb. I thought the 64 bit kernel avoided all problems 
> > > with having lots of memory? Or should I pass the kernel a parameter?
> > >
> > > I had a quick search through the list but couldn't see anything 
> > > relevant.
> > >   
> >
> >
> > Does your bios have an option for mapping memory from 3-4GB up to 4-5GB
> > so the PCI memory hole at 3-4GB won't overlap with it?
> >
> > This is sometimes called a memory hole (and you want to make one).
> >
> > The kernel can then use all the memory since 4GB is not a limit for it.
> >
> > Len Sorensen
> >  
> This was in deed the culprit! Once you had mentioned the memory hole I 
> was able to find a lot more information on this. Setting the memory hole 
> mapping to [Software] on the Tyan motherboard gave me 4GB immediately.
>
> Thanks a lot for your help!
>
> Koen.