Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754675AbZGNKaz (ORCPT ); Tue, 14 Jul 2009 06:30:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754574AbZGNKaz (ORCPT ); Tue, 14 Jul 2009 06:30:55 -0400 Received: from dallas.jonmasters.org ([72.29.103.172]:34755 "EHLO dallas.jonmasters.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754562AbZGNKax (ORCPT ); Tue, 14 Jul 2009 06:30:53 -0400 Subject: Re: [PATCH] reduce export symbol CRC table size on 64-bit archs From: Jon Masters To: Jan Beulich Cc: Michal Marek , Ingo Molnar , tony.luck@intel.com, Thomas Gleixner , Rusty Russell , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, hpa@zytor.com In-Reply-To: <4A5B101E020000780000A284@vpn.id2.novell.com> References: <4A4A18780200007800008345@vpn.id2.novell.com> <4A4E671C.2090201@suse.cz> <4A51C71B0200007800008EE2@vpn.id2.novell.com> <200907092044.22108.rusty@rustcorp.com.au> <4A57089B0200007800009C0E@vpn.id2.novell.com> <4A5AEC3C.2060608@suse.cz> <4A5B101E020000780000A284@vpn.id2.novell.com> Content-Type: text/plain Organization: World Organi[sz]ation of Broken Dreams Date: Tue, 14 Jul 2009 06:29:32 -0400 Message-Id: <1247567372.31188.229.camel@perihelion.bos.jonmasters.org> Mime-Version: 1.0 X-Mailer: Evolution 2.24.5 (2.24.5-1.fc10) Content-Transfer-Encoding: 7bit X-SA-Do-Not-Run: Yes X-SA-Exim-Connect-IP: 74.92.29.237 X-SA-Exim-Mail-From: jonathan@jonmasters.org X-SA-Exim-Scanned: No (on dallas.jonmasters.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1253 Lines: 26 On Mon, 2009-07-13 at 09:44 +0100, Jan Beulich wrote: > >>> Michal Marek 13.07.09 10:11 >>> > >Jan Beulich napsal(a): > >> Actually I meanwhile think that module-init-tools can easily detect the changed > >> layout without any further kernel side adjustments: Since it is known that a > >> CRC always is a 32-bit value, simply checking whether the so-far-used 64-bit > >> value has more than 32 significant bits should suffice: If so, the new layout > >> is being used (with the symbol name starting at offset 4), else the old one is > >> in effect (name at offset 8). This ought to be a pretty trivial change to that > >> code. > > > >But old module-init-tools will continue reading garbage in this case. Most of the distros can fix that with a dependency on the kernel package in the absolute worst case, not that I love that idea, but it happens. I assume for now we are going with detecting the two possibilities because it doesn't really hurt in any case to have this support. Jon. -- 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/