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Date: Fri, 10 Aug 2007 10:34:46 +1000
From: "Michael Ellerman" <michael@ellerman.id.au>
To: ljhc@br.ibm.com
Subject: Re: SLUB doesn't work with kdump kernel on Cell
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
       "Christoph Lameter" <clameter@sgi.com>,
       "Arnd Bergmann" <arndb@arndb.de>, cbe-oss-dev@ozlabs.org
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On 8/9/07, Lucio Correia <ljhc@br.ibm.com> wrote:
> On Wed, 2007-08-08 at 23:10 +0200, Arnd Bergmann wrote:
> > On Wednesday 08 August 2007, Lucio Correia wrote:
> > >   DMA             0 ->    12288
> > >   Normal      12288 ->    12288
> > > early_node_map[2] active PFN ranges
> > >     0:        0 ->     2560
> > >     1:    12287 ->    12288
> >
> > As Christoph found, this memory map is really strange. Other machines
> > have something like
> >
> > Zone PFN ranges:
> >   DMA             0 ->    16384
> >   Normal      16384 ->    16384
> > early_node_map[2] active PFN ranges
> >     0:        0 ->     8192
> >     1:     8192 ->    16384
> >
> > Lucio,
> > What code builds the memory map that gets passed to the kdump kernel?

It comes out of the device tree, just like a regular kernel. The
device tree for the kdump kernel is built by kexec-tools, it parses
/proc/device-tree and does a bunch of logic to avoid various reserved
regions: the kernel, TCE tables, RTAS etc.

> I also tried to pass maxcpus=1 for the command line of second kernel,
> and it didn't work. How can I alternatively disable the node?

maxcpus is poorly tested and is known to be broken on Cell, please
don't use it, or fix it first :)

cheers