From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754618Ab1HBQaB (ORCPT ); Tue, 2 Aug 2011 12:30:01 -0400 Received: from bipbip.grupopie.com ([195.23.16.24]:59222 "EHLO bipbip.grupopie.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754557Ab1HBQ34 (ORCPT ); Tue, 2 Aug 2011 12:29:56 -0400 Message-ID: <4E382602.6050308@grupopie.com> Date: Tue, 02 Aug 2011 17:29:54 +0100 From: Paulo Marques Organization: Grupo PIE User-Agent: Thunderbird 2.0.0.23 (X11/20090817) MIME-Version: 1.0 To: Tomasz Figa CC: Russell King - ARM Linux , linux-arm-kernel@lists.infradead.org, Kukjin Kim , linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, "'Ben Dooks'" Subject: Re: Question about "Inconsistent kallsyms data" References: <02ae01cc4d91$aed71670$0c854350$%kim@samsung.com> <20110729100241.GB25640@n2100.arm.linux.org.uk> <2563791.8cBqodrk1o@flatron> <1514384.7oMe1aulyC@flatron> In-Reply-To: <1514384.7oMe1aulyC@flatron> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Tomasz Figa wrote: > On Friday 29 of July 2011 at 12:58:32, Tomasz Figa wrote: >>[...] >> I will try to bisect the case with s3c6400 defconfig. > > I have no idea why, but I cannot reproduce the issue anymore, even after make > distclean or starting with a clean tree. A build system bug? > > I do not know much technical details about the kernel build system, but might > it be a concurrency issue (I use make -j5 for building with 5 jobs)? Usually this is caused by symbols moving slightly between kernel compiles. This is an explanation of the process I wrote a while ago in a different thread at LKML: > Now as for CONFIG_KALLSYMS_EXTRA_PASS: to build the kallsyms table, the > build process first links a kernel image with an empty kallsyms table > and use that to fetch information for all the symbols. > > It then uses that information to build the table with the right size, > and links it again. If everything goes ok, this new version as all the > symbols in the correct places and the final table can be built with the > correct addresses. > > The final linking should produce the same result as only the data on the > kallsyms table changed, but not its size. > > However, there have been bugs in the past with section alignments and > symbol reordering for symbols with the same address, etc., etc. that > make this final table not have the exact same size, and the build fails > with an inconsistent kallsyms data message. At this point, the user can > turn on the CONFIG_KALLSYMS_EXTRA_PASS and temporarily solve the problem > while the developers find the correct fix. Without this option, in this > situation the kernel would simply fail the compilation. > > All this has been stable for a while and this option hasn't been needed > recently (AFAIK), but if there is some bug in some new binutils or > something, the option might be needed again. To check inconsistencies, the Makefile compares ".tmp_System.map" and "System.map" for differences. On a normal build they should be identical, but if this fails with "Inconsistent kallsyms data" you could try comparing the two files to check which symbols are causing trouble. -- Paulo Marques - www.grupopie.com "All generalizations are false."