Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161303Ab3DGBWd (ORCPT ); Sat, 6 Apr 2013 21:22:33 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:57664 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161232Ab3DGBWc (ORCPT ); Sat, 6 Apr 2013 21:22:32 -0400 User-Agent: K-9 Mail for Android In-Reply-To: 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> <1365156435.1970.31.camel@dabdike> <87wqsgjm6i.fsf@rustcorp.com.au> <1365245524.4298.14.camel@dabdike.spectrum.wifi> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: Re: [PATCH] Add non-zero module sections to sysfs From: James Bottomley Date: Sat, 06 Apr 2013 18:22:21 -0700 To: John David Anglin CC: Rusty Russell , Sebastian Wankerl , linux-kernel@vger.kernel.org, Philip Kranz , i4passt@lists.informatik.uni-erlangen.de, linux-parisc@vger.kernel.org, corbet@lwn.net Message-ID: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2627 Lines: 74 John David Anglin wrote: >On 6-Apr-13, at 6:52 AM, James Bottomley wrote: > >> On Sat, 2013-04-06 at 15:22 +1030, Rusty Russell wrote: >>>> 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? >>> >>> Yep. The original patch didn't go through me, or we would have had > >>> this >>> discussion back then... >>> >>> The use of section names in sysfs goes back to one Mr. Corbet. Why > >>> did >>> he do it that way? Because gdb's add-symbol-file makes the same >>> assumption. So if we fixed the sysfs somehow, it still wouldn't be >>> useful, since there's no way to tell gdb :( >>> >>> The real answer don't use -ffunction-sections on modules: probably >>> not >>> as important as the rest of the kernel. And the new shiny is >>> -flto anyway. >>> >>> And that leaves us with a PA-RISC specific issue, for which we >should >>> move the fix to PA-RISC. >>> >>> Thoughts? >> >> Well, we don't have much of a choice. Our ELF stub jump on 32 bits >> is a >> PCREL17. That means once a module size is over 128k there's a >> chance we >> might not be able to link it because the jump is too big for the >> instruction. IPV6 is one such big module today, but I'm sure there >> are >> others. The only way I know to fix this is to allow the linker to >> insert stubs between functions, so we only fail at linking if a >single >> function is >128k big. The way to do this is -ffunction-sections, >> unless there's something else we could do (all we really need is a >way >> to ensure we can insert ELF stubs every 128k). > >There is now a config work around for this. See: >http://www.spinics.net/lists/linux-parisc/msg04521.html The longcalls config option only works on pa2 doesn't it? Although we could just deprecate pa1. James -- Sent from my Android phone with K-9 Mail. Please excuse my brevity and top posting. -- 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/