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Subject: Re: [RFC][patch 0/2] mm: remove PageReserved
From: Arjan van de Ven <arjan@infradead.org>
To: Russell King <rmk+lkml@arm.linux.org.uk>
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Date: Tue, 09 Aug 2005 10:38:39 +0200
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On Tue, 2005-08-09 at 08:08 +0100, Russell King wrote:
> On Tue, Aug 09, 2005 at 02:59:53PM +1000, Nick Piggin wrote:
> > That would work for swsusp, but there are other users that want to
> > know if a struct page is valid ram (eg. ioremap), so in that case
> > swsusp would not be able to mess with the flag.
> 
> The usage of "valid ram" here is confusing - that's not what PageReserved
> is all about.  It's about valid RAM which is managed by method other
> than the usual page counting.  Non-reserved RAM is also valid RAM, but
> is managed by the kernel in the usual way.
> 
> The former is available for remap_pfn_range and ioremap, the latter is
> not.
> 
> On the other hand, the validity of an apparant RAM address can only be
> tested using its pfn with pfn_valid().
> 
> Can we straighten out the terminology so it's less confusing please?
> 

and..... can we make a general page_is_ram() function that does what it
says? on x86 it can go via the e820 table, other architectures can do
whatever they need....