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Date: Wed, 3 Oct 2007 08:56:07 +1000
From: Paul Mackerras <paulus@samba.org>
To: Badari Pulavarty <pbadari@us.ibm.com>
Subject: Re: [RFC] PPC64 Exporting memory information through /proc/iomem
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Cc: linuxppc-dev@ozlabs.org, anton@au1.ibm.com,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	linux-mm <linux-mm@kvack.org>
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Badari Pulavarty writes:

> I am trying to get hotplug memory remove working on ppc64.
> In order to verify a given memory region, if its valid or not -
> current hotplug-memory patches used /proc/iomem. On IA64 and
> x86-64 /proc/iomem shows all memory regions. 
> 
> I am wondering, if its acceptable to do the same on ppc64 also ?

I am a bit hesitant to do that, since /proc/iomem is user visible and
is therefore part of the user/kernel ABI.  Also it feels a bit weird
to have system RAM in something whose name suggests it's about MMIO.

> Otherwise, we need to add arch-specific hooks in hotplug-remove
> code to be able to do this.

Isn't it just a matter of abstracting the test for a valid range of
memory?  If it's really hard to abstract that, then I guess we can put
RAM in iomem_resource, but I'd rather not.

Thanks,
Paul.