Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161734Ab3DEKHV (ORCPT ); Fri, 5 Apr 2013 06:07:21 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:52314 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752005Ab3DEKHT (ORCPT ); Fri, 5 Apr 2013 06:07:19 -0400 Message-ID: <1365156435.1970.31.camel@dabdike> Subject: Re: [PATCH] Add non-zero module sections to sysfs From: James Bottomley To: Rusty Russell Cc: Sebastian Wankerl , linux-kernel@vger.kernel.org, Philip Kranz , i4passt@lists.informatik.uni-erlangen.de, linux-parisc@vger.kernel.org Date: Fri, 05 Apr 2013 12:07:15 +0200 In-Reply-To: <87vc81lj7x.fsf@rustcorp.com.au> References: <1364994499-23708-1-git-send-email-sisewank@cip.cs.fau.de> <87mwtf3ya1.fsf@rustcorp.com.au> <515D4A7F.5070102@cip.cs.fau.de> <87vc81lj7x.fsf@rustcorp.com.au> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.6.3 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2143 Lines: 49 On Fri, 2013-04-05 at 14:30 +1030, Rusty Russell wrote: > Sebastian Wankerl writes: > > On 04/04/13 03:00, Rusty Russell wrote: > >> Sebastian Wankerl writes: > >>> Add non-zero module sections to sysfs on architectures unequal to PARISC. > >>> KGDB needs all module sections for proper module debugging. Therefore, commit > >>> 35dead4235e2b67da7275b4122fed37099c2f462 is revoked except for PARISC > >>> architecture. Thanks for actually cc'ing us. > >> #ifdef CONFIG_PARISC in the middle of kernel/module.c is super-ugly, and > >> wrong. > > > > I don't see why this is wrong. It used to load all sections to sysfs > > until the patch mentioned. Actually, it is the PARISC build chain which > > is broken. > > Exactly. Don't workaround it here, revert it and put the > duplicate-section-name fixup in parisc where it belongs. > > Assuming parisc still produces these dup sections: that patch is 4 years > old now. Just so you know: this isn't a parisc specific problem. Gcc produces duplicate section names under various circumstances, but the one that bites us is -ffunction-sections. Note that there are proposals to use -ffunction-sections on all architectures (so we can garbage collect unused functions) in which case you'll induce the bug identified in 35dead4235e2b67da7275b4122fed37099c2f462 on every architecture The problem is our assumption that section names be unique. This assumption is wrong. The ELF spec says (version 1.1 page 1-15): "An object file may have more than one section with the same name." We need to fix the kernel not to rely on a bogus assumption ... but we had no idea how to do that in a way that preserved the backwards compatibility of sections subdirectory. I admit that 35dead4235e2b67da7275b4122fed37099c2f462 is a hack, but now the problem has got attention, can we fix it properly? James -- 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/