Re: i686 SMP systems with more then 12 GB ram with 2.4.x kernel ?

[Daniel Freedman <freedman@ccmr.cornell.edu>]

On Jan 01 2002, H. Peter Anvin (hpa@zytor.com) wrote:
> By author: Alan Cox <alan@lxorguk.ukuu.org.uk>
> >
> > > 2. Isn't the boundary at 2^30 really irrelevant and the three "correct"
> > > zones are (0 - 2^24-1), (2^24 - 2^32-1) and (2^32 - 2^36-1)?
> >
> > Nope. The limit for directly mapped memory is 2^30.
> >
> 
> 2^30-2^27 to be exact (assuming a 3:1 split and 128MB vmalloc zone.)
> 
>         -hpa

For my better understanding, where's the 128MB vmalloc zone assumption
defined, please?

I'm pretty sure I understand that the 3:1 split you refer to is
defined by PAGE_OFFSET in asm-i386/page.h

But when I tried to find the answer in the source for the vmalloc
zone, I looked in linux/mm.h, linux/mmzone.h, linux/vmalloc.h, and
mm/vmalloc.c, but couldn't find anything there or in O'Reilly's kernel
book that I could follow/understand.

Thanks for any pointers.

Take care,

Daniel

-- 
Daniel A. Freedman
Laboratory for Atomic and Solid State Physics
Department of Physics
Cornell University