From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750793AbWAOS7a (ORCPT ); Sun, 15 Jan 2006 13:59:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750799AbWAOS7a (ORCPT ); Sun, 15 Jan 2006 13:59:30 -0500 Received: from mx1.redhat.com ([66.187.233.31]:55262 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1750793AbWAOS7a (ORCPT ); Sun, 15 Jan 2006 13:59:30 -0500 Subject: Re: 2.6.15-rt4 failure with LATENCY_TRACE on x86_64 From: Clark Williams To: Mikael Andersson Cc: Steven Rostedt , lkml , Ingo Molnar In-Reply-To: <43C88833.9050107@karett.se> References: <1137103652.11354.40.camel@localhost.localdomain> <1137122280.7338.6.camel@localhost.localdomain> <1137164761.3332.2.camel@localhost.localdomain> <1137167679.7241.25.camel@localhost.localdomain> <1137193088.3170.34.camel@localhost.localdomain> <43C88833.9050107@karett.se> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-t2iNG+9vXxq7sUELoqao" Date: Sun, 15 Jan 2006 12:59:10 -0600 Message-Id: <1137351550.3627.15.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --=-t2iNG+9vXxq7sUELoqao Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Sat, 2006-01-14 at 06:12 +0100, Mikael Andersson wrote: > Steven Rostedt wrote: > > On Fri, 13 Jan 2006, Clark Williams wrote: > >>Have you tried booting your system with a up kernel? > >> > > Not a x86_64 up. But serveral up i386 boxes. > >=20 >=20 > I had a very similar problem on a x86_64 up. I got a segfault in init=20 > with LATENCY_TRACE enabled on 2.6.15-rt2. > I get it at ffffffff8010fe30, which should be mcount according to my=20 > System.map [1]. It seems a bit weird because i have tried to alter=20 > mcount somewhat. Initially by removing the initial comparison, but later > i tried a few other things also. Nothing had any effect at all. Glad to see that I'm not completely insane :). >=20 > AFAIK glibc also has a mcount symbol, and it's almost as if ld.so would=20 > have linked the glibc mcount symbol to the kernel symbol mcount. That > would naturally lead to a pagefault :) > And it would be consistent with the fact that statically linked shells > works. >=20 > It's probably something completely different, bevause that would be=20 > really weird. OTOH, it was really weird that i could change the asm for=20 > mcount in entry.S without any effect whatsoever. >=20 Yeah, I don't really see how ld.so would know about the kernel mcount. AFAIK it only knows about symbols exported from ELF libraries that it has loaded in user space.=20 I'm still trying to figure out if LATENCY_TRACE could effect do_execve(), since that's the routine that starts the init program. I'm wondering if do_execve() is doing something that aggrevates ld.so, so that it loads the program and/or libraries incorrectly. Guess that's what I'll be doing Monday morning... Clark --=20 Clark Williams --=-t2iNG+9vXxq7sUELoqao Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQBDypt+Hyuj/+TTEp0RAmd5AJ9CR5wpHoGGLKpbvAFUG2+G8QkRuwCg4HWJ qEM4kThjgKoRHWxuwfX14Ss= =Mlrf -----END PGP SIGNATURE----- --=-t2iNG+9vXxq7sUELoqao--