From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936500AbXHHD5b (ORCPT ); Tue, 7 Aug 2007 23:57:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934330AbXHHD5V (ORCPT ); Tue, 7 Aug 2007 23:57:21 -0400 Received: from waste.org ([66.93.16.53]:47590 "EHLO waste.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934265AbXHHD5U (ORCPT ); Tue, 7 Aug 2007 23:57:20 -0400 Date: Tue, 7 Aug 2007 22:51:21 -0500 From: Matt Mackall To: Alan Cox Cc: Dave Hansen , linux-kernel@vger.kernel.org, serue@us.ibm.com Subject: Re: [RFC][PATCH 1/5] pagemap: remove file header Message-ID: <20070808035121.GL30556@waste.org> References: <20070807223300.9228E0E0@kernel> <20070808011620.GF30556@waste.org> <20070808023100.222c4d15@the-village.bc.nu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070808023100.222c4d15@the-village.bc.nu> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 08, 2007 at 02:31:00AM +0100, Alan Cox wrote: > O> > The endianness is only useful when examining a raw dump of > > > pagemap from a different machine when you don't know the > > > source of the file. This is pretty rare, and the programs > > > or scripts doing the copying off-machine can certainly be > > > made to hold this information. > > Nobody fancies doing bi-endian MIPS ? Indeed not. > > > The page size is available in userspace at least with libc's > > > getpagesize(). This will also never vary across processes, > > For now. Its a logical direction however thant we end up with bigger page > sizes either by hardware or by software merging and end up having > different page sizes for legacy 32bit binaries. Blerch. > > I'd really strongly prefer to have no header. It was added to > > futureproof the thing. > > The information needed to parse /proc/pid/pagemap can be stuck > in /proc/pid/somewherelese. If we ever get page size variations and the > like then /proc/pid/ is going to end up with that information anyway for > ps and friends to use. Well if somewhereelse doesn't exist today, programs written today will break on tomorrow's kernels. -- Mathematics is the supreme nostalgia of our time.