From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx178.postini.com [74.125.245.178]) by kanga.kvack.org (Postfix) with SMTP id F03786B0070 for ; Wed, 4 Jul 2012 19:06:20 -0400 (EDT) Date: Thu, 5 Jul 2012 01:05:47 +0200 From: Andrea Arcangeli Subject: Re: [PATCH 04/40] xen: document Xen is using an unused bit for the pagetables Message-ID: <20120704230547.GO25743@redhat.com> References: <1340888180-15355-1-git-send-email-aarcange@redhat.com> <1340888180-15355-5-git-send-email-aarcange@redhat.com> <4FEDB8AC.4000209@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FEDB8AC.4000209@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Hillf Danton , Dan Smith , Peter Zijlstra , Linus Torvalds , Andrew Morton , Thomas Gleixner , Ingo Molnar , Paul Turner , Suresh Siddha , Mike Galbraith , "Paul E. McKenney" , Lai Jiangshan , Bharata B Rao , Lee Schermerhorn , Johannes Weiner , Srivatsa Vaddagiri , Christoph Lameter , Alex Shi , Mauricio Faria de Oliveira , Konrad Rzeszutek Wilk , Don Morris , Benjamin Herrenschmidt On Fri, Jun 29, 2012 at 10:16:12AM -0400, Rik van Riel wrote: > On 06/28/2012 08:55 AM, Andrea Arcangeli wrote: > > Xen has taken over the last reserved bit available for the pagetables > > which is set through ioremap, this documents it and makes the code > > more readable. > > > > Signed-off-by: Andrea Arcangeli > > --- > > arch/x86/include/asm/pgtable_types.h | 11 +++++++++-- > > 1 files changed, 9 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h > > index 013286a..b74cac9 100644 > > --- a/arch/x86/include/asm/pgtable_types.h > > +++ b/arch/x86/include/asm/pgtable_types.h > > @@ -17,7 +17,7 @@ > > #define _PAGE_BIT_PAT 7 /* on 4KB pages */ > > #define _PAGE_BIT_GLOBAL 8 /* Global TLB entry PPro+ */ > > #define _PAGE_BIT_UNUSED1 9 /* available for programmer */ > > -#define _PAGE_BIT_IOMAP 10 /* flag used to indicate IO mapping */ > > +#define _PAGE_BIT_UNUSED2 10 > > Considering that Xen is using it, it is not really > unused, is it? _PAGE_BIT_UNUSED1 is used too (_PAGE_BIT_SPECIAL). Unused stands for unused by the CPU, not by the OS. But this patch is dropped. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org