Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755159AbYHABLs (ORCPT ); Thu, 31 Jul 2008 21:11:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752686AbYHABLj (ORCPT ); Thu, 31 Jul 2008 21:11:39 -0400 Received: from mx2.suse.de ([195.135.220.15]:52278 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752671AbYHABLi (ORCPT ); Thu, 31 Jul 2008 21:11:38 -0400 Date: Fri, 1 Aug 2008 03:11:37 +0200 From: Nick Piggin To: Kumar Gala Cc: linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org, Benjamin Herrenschmidt Subject: Re: [PATCH] powerpc/mm: Implement _PAGE_SPECIAL & pte_special() for 32-bit Message-ID: <20080801011137.GA20407@wotan.suse.de> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1367 Lines: 33 On Thu, Jul 31, 2008 at 01:48:31PM -0500, Kumar Gala wrote: > Implement _PAGE_SPECIAL and pte_special() for 32-bit powerpc. This bit will > be used by the fast get_user_pages() to differenciate PTEs that correspond > to a valid struct page from special mappings that don't such as IO mappings > obtained via io_remap_pfn_ranges(). > > We currently only implement this on sub-arch that support SMP or will so > in the future (6xx, 44x, FSL-BookE) and not (8xx, 40x). > > Signed-off-by: Kumar Gala Cool > --- > Nick, do you forsee using _PAGE_SPECIAL for other applications that would > be of interested to non-SMP hw? > > We can look at adding it into 8xx and 40x, but was being lazy as I assume > there is no point. I don't forsee it being used for anything else, but it is possible I guess. We currently will also use it in the VM (vm_normal_page), turning that function into a much more compact and simple version. It doesn't do a great deal for performance, but you _may_ want to consider using it just so the entire powerpc architecture takes this same path. Not a big deal though. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/