From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Marek Subject: Re: [PATCH] reduce export symbol CRC table size on 64-bit archs Date: Mon, 13 Jul 2009 10:11:40 +0200 Message-ID: <4A5AEC3C.2060608@suse.cz> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4A57089B0200007800009C0E-Qfbpwmsw6RoS3W1tAdPHOtBPR1lH4CV8@public.gmane.org> Sender: linux-modules-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jan Beulich Cc: Rusty Russell , Ingo Molnar , tony.luck-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, Jon Masters , Thomas Gleixner , linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-modules-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org List-Id: linux-arch.vger.kernel.org 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. Michal -- To unsubscribe from this list: send the line "unsubscribe linux-modules" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cantor.suse.de ([195.135.220.2]:34570 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751376AbZGMILm (ORCPT ); Mon, 13 Jul 2009 04:11:42 -0400 Message-ID: <4A5AEC3C.2060608@suse.cz> Date: Mon, 13 Jul 2009 10:11:40 +0200 From: Michal Marek MIME-Version: 1.0 Subject: Re: [PATCH] reduce export symbol CRC table size on 64-bit archs 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> In-Reply-To: <4A57089B0200007800009C0E@vpn.id2.novell.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Jan Beulich Cc: Rusty Russell , Ingo Molnar , tony.luck@intel.com, Jon Masters , Thomas Gleixner , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, hpa@zytor.com Message-ID: <20090713081140.UfECIcwI64uwtfdlrXM7Z6Pp-ifjouZullZ2sI9Cbnw@z> 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. Michal