Reserved pages in PowerPC

Ankita Garg ankita at
Tue Sep 28 20:28:51 EST 2010

Hi Ben,

On Fri, Sep 17, 2010 at 07:52:31AM +1000, Benjamin Herrenschmidt wrote:
> On Thu, 2010-09-16 at 17:38 +0530, Ankita Garg wrote:
> > Thanks Ben for taking a look at this. So I checked the rtas messages
> > on
> > the serial console and see the following:
> > 
> > instantiating rtas at 0x000000000f632000... done
> > 
> > Which does not correspond to the higher addresses that I see as
> > reserved
> > (observation on a 16G machine). 
> Well, I'd suggest you audit prom_init.c which builds the reserve map,
> and the various memblock_reserve() calls in prom.c

I studied and instrumented memblock_reserve() and also reserve_mem().
However, all the reserved addresses seem to correspond to lower memory.
I also observed that these reserved addresses are accessed quite rapidly
when a workload is being run.. 

Ankita Garg (ankita at
Linux Technology Center
IBM India Systems & Technology Labs,
Bangalore, India

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