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Subject: Re: [PATCH 0/8] v5 De-couple sysfs memory directories from memory
	sections
From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
In-Reply-To: <20100812120816.e97d8b9e.akpm@linux-foundation.org>
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	<20100812120816.e97d8b9e.akpm@linux-foundation.org>
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Date: Thu, 12 Aug 2010 13:07:03 -0700
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Cc: linuxppc-dev@ozlabs.org, Greg KH <greg@kroah.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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On Thu, 2010-08-12 at 12:08 -0700, Andrew Morton wrote:
> > This set of patches allows for each directory created in sysfs
> > to cover more than one memory section.  The default behavior for
> > sysfs directory creation is the same, in that each directory
> > represents a single memory section.  A new file 'end_phys_index'
> > in each directory contains the physical_id of the last memory
> > section covered by the directory so that users can easily
> > determine the memory section range of a directory.
> 
> What you're proposing appears to be a non-back-compatible
> userspace-visible change.  This is a big issue! 

Nathan, one thought to get around this at the moment would be to bump up
the size that we export in /sys/devices/system/memory/block_size_bytes.
I think you have already done most of the hard work to accomplish
this.  

You can still add the end_phys_index stuff.  But, for now, it would
always be equal to start_phys_index.

-- Dave