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Re: DISCONTIGMEM suuport on 32 bits MIPS

To: Franck <vagabon.xyz@gmail.com>
Subject: Re: DISCONTIGMEM suuport on 32 bits MIPS
From: Ralf Baechle <ralf@linux-mips.org>
Date: Fri, 30 Sep 2005 14:49:00 +0100
Cc: linux-mips@linux-mips.org
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On Fri, Sep 30, 2005 at 02:40:31PM +0200, Franck wrote:

> > > > IP27 currently the only system that absolutely needs discontiguous
> > > > memory in order to work at all.  A few other systems could make use of
> > > > discontiguous memory to reduce the waste of memory - the family of
> > > > Broadcom SB1 based systems comes to mind.
> > >
> > > Isn't discontiguous memory common for embedded system as well ? I
> > > thought so...Anyways can we make discontiguous memory thing move into
> > > generic MIPS code so every future needs for that will profit ? I
> > > looked at other arch, and they seem to implement it that way (in
> > > arch/xxx/mm/discontig.c).
> >
> > Yes, that would be a good thing.  There are several platforms that could
> > make good use of discontiguous memory support such as Broadcom's Sibyte
> > SoCs with their insanely large hole in the memory map but also others.
> >
> 
> Ok I'll try to do that soon (maybe in 1 or 2 weeks). I looked at the
> ARM's code and I should be able to do the same on MIPS. Should I keep
> IP27 data structure and code although ARM's ones seem to be easier to
> understand ?

The IP27 code is a little obscure which partly is explained by it's age;
it's been the first NUMA system to be supported in Linux.  After a
quick look the ARM code seems a little to simple to deal with such a
system, so I suggest you take a look at arch/ia64/mm/discontig.c instead.

  Ralf

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