From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753045Ab1ARRbC (ORCPT ); Tue, 18 Jan 2011 12:31:02 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.125]:63243 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751753Ab1ARRbA (ORCPT ); Tue, 18 Jan 2011 12:31:00 -0500 X-Authority-Analysis: v=1.1 cv=3uSaImBeuprzHBlOOPjkqgu+7PcxSRW0m2Aphm9Zmck= c=1 sm=0 a=44vUGAvzfu8A:10 a=Q9fys5e9bTEA:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=meVymXHHAAAA:8 a=z535ck_rp2hYom-GMYUA:9 a=xnCV3-hW4E0lKxRtkqYA:7 a=PPYM95O3msjrbAkCPW0uIGdYK0oA:4 a=PUjeQqilurYA:10 a=jeBq3FmKZ4MA:10 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Subject: Re: Bug#609371: linux-image-2.6.37-trunk-sparc64: module scsi_mod: Unknown relocation: 36 From: Steven Rostedt To: David Miller Cc: richm@oldelvet.org.uk, 609371@bugs.debian.org, ben@decadent.org.uk, sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, fweisbec@gmail.com, mingo@redhat.com, Jesper.Nilsson@axis.com, jeffm@suse.com, mathieu.desnoyers@efficios.com In-Reply-To: <20110117.223513.183031917.davem@davemloft.net> References: <20110116.220755.179947617.davem@davemloft.net> <1295259761.32152.20.camel@duncow> <1295273741.16479.19.camel@gandalf.stny.rr.com> <20110117.223513.183031917.davem@davemloft.net> Content-Type: text/plain; charset="ISO-8859-15" Date: Tue, 18 Jan 2011 12:30:56 -0500 Message-ID: <1295371856.12215.29.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2011-01-17 at 22:35 -0800, David Miller wrote: > From: Steven Rostedt > Date: Mon, 17 Jan 2011 09:15:41 -0500 > > > Again, this is to help the linker keep arrays in tacked. Tracepoints are > > allocated into the tracepoint section, and then read like an array. If > > the linker adds holes as it links sections into one big one, then the > > reading of the array breaks. > > > > We either need to compact it (with the align(4)) which is undesirable, > > or add our own holes like the above does. > > Just take away all of the align directives, it should just work. If that was the case, we would have never added it :-) > > If it doesn't, then we should investigate to find out the real reason > why. OK, we can remove it and I can see what breaks. > > The linker has no reason to add holes, and in fact if we are to believe > the commit message for 86c38a31aa7f2dd6e74a262710bf8ebf7455acc5 > ("tracing: Fix ftrace_event_call alignment for use with gcc 4.5"), with > gcc-4.x where x < 5, it did work even though some ftrace_event_call > declarations lacked the align directive. > > If this align thing is so critical, why don't we need it for the > exception table entries which live in the "__ex_table" section in the > kernel? It's the same _exact_ kind of thing, and the asm sequence we > use to populate it is identical to what GCC emits for the tracing > object declarations in question. But aren't the __ex_table entries just two words? Which would align nicely regardless. The ftrace_event_call is a relatively large structure, as it may end on a 4 byte alignement, the linker may start the next section with more space to get it back to a 8 byte alignment. This is assuming that x86_64 packs the array in 4 bytes. Hmm, perhaps changing the alignment in vmlinux.lds.h would fix that. Anyway, I'll revert that commit and see if I can break it again. If so, then I'll look for other solutions. Thanks! -- Steve