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From: David Howells <dhowells@redhat.com>
To: Nick Piggin <npiggin@suse.de>
Cc: dhowells@redhat.com,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Hugh Dickins <hugh@veritas.com>,
	Jared Hulbert <jaredeh@gmail.com>,
	Carsten Otte <cotte@de.ibm.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	linux-arch@vger.kernel.org
Subject: Re: [rfc][patch 2/2] mm: introduce optional pte_special pte bit
Date: Wed, 16 Jan 2008 17:14:35 +0000	[thread overview]
Message-ID: <16391.1200503675@redhat.com> (raw)
In-Reply-To: <20080113031013.GD22285@wotan.suse.de>

Nick Piggin <npiggin@suse.de> wrote:

> Unfortunately, not all architectures can spare a bit in the pte for this. So
> add an ifdefs, depending on whether the arch can support it or not.  Although
> pte_special can remove all restrictions that pfn mappings currently have, we
> continue to enforce those restrictions even on architectures that have the new
> pte bit, for consistency.

FRV has a single bit to spare in its PTEs (xAMPRx_RESERVED13) that you could
use.

MN10300 (which is currently lurking in the -mm tree) has no spare bits unless
I can drop either the PAGE_ACCESSED or PAGE_NX bits.

David

      parent reply	other threads:[~2008-01-16 17:15 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-13  3:08 [rfc] changes to user memory mapping scheme Nick Piggin
2008-01-13  3:09 ` [rfc][patch 1/2] mm: introduce VM_MIXEDMAP Nick Piggin
2008-01-13  3:10 ` [rfc][patch 2/2] mm: introduce optional pte_special pte bit Nick Piggin
2008-01-13  3:41   ` Linus Torvalds
2008-01-13  4:39     ` Nick Piggin
2008-01-13  4:45       ` Linus Torvalds
2008-01-13  5:06         ` Nick Piggin
2008-01-13 16:50           ` Linus Torvalds
2008-01-13 20:46             ` Martin Schwidefsky
2008-01-14 21:04             ` Jared Hulbert
2008-01-15  9:18               ` Carsten Otte
2008-01-16  3:38             ` Nick Piggin
2008-01-16  4:04               ` Linus Torvalds
2008-01-16  4:37                 ` Nick Piggin
2008-01-16  4:48                   ` Linus Torvalds
2008-01-16  4:51                     ` David Miller
2008-01-16  5:23                       ` Linus Torvalds
2008-01-16  5:48                         ` Nick Piggin
2008-01-16  9:52                           ` Martin Schwidefsky
2008-01-16  5:17                     ` Nick Piggin
2008-01-16 10:52                       ` Catalin Marinas
2008-01-16 18:18                         ` Russell King
2008-01-16 17:21                       ` Linus Torvalds
2008-01-16 17:14   ` David Howells [this message]

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