Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756078AbYJTR2g (ORCPT ); Mon, 20 Oct 2008 13:28:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752557AbYJTR21 (ORCPT ); Mon, 20 Oct 2008 13:28:27 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:39997 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751518AbYJTR21 (ORCPT ); Mon, 20 Oct 2008 13:28:27 -0400 Date: Mon, 20 Oct 2008 13:28:24 -0400 (EDT) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Josh Boyer cc: Andrew Morton , Peter Zijlstra , linux-kernel@vger.kernel.org, David Miller , linuxppc-dev@ozlabs.org, Ingo Molnar , Thomas Gleixner Subject: Re: [PATCH 0/2] ftrace: fixes for PPC In-Reply-To: <20081020170808.GB7249@yoda.jdub.homelinux.org> Message-ID: References: <20080906050602.409299112@goodmis.org> <20080906120346.GA30964@elte.hu> <20081016181452.GA29739@yoda.jdub.homelinux.org> <20081016183529.GB29739@yoda.jdub.homelinux.org> <20081016150106.6ddf7e46@zod.rchland.ibm.com> <20081020170808.GB7249@yoda.jdub.homelinux.org> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1637 Lines: 40 On Mon, 20 Oct 2008, Josh Boyer wrote: > On Mon, Oct 20, 2008 at 12:30:33PM -0400, Steven Rostedt wrote: > >> Anyway, if you want a tester let me know. It seems 2.6.27.1 should be > >> fine since FTRACE was disabled, but for .28-rc1 it would be cool if it > >> worked :). > > > >Hi Josh, > > > >I've been looking deeper at the code for PPC. I realized that my PPC64 box > >that I've been testing on did not use modules. While looking at the module > >code it dawned on me the dynamic ftrace needs a bit of work. This is > >because the way modules are handled in PPC (and other architectures as > >well). The jmps used by mcount is a 24 bit jump. Since the modules are > >loaded farther than 24bits away, a trampoline is needed. > > Ah, indeed. > > >A bit of rework is needed in the ftrace infrastructure to handle the > >trampoline. Too much work to go into 28. I'll start working on code that > >can hopefully be ready and tested for 29. It's not that major of a change, > >but since the merge window for 28 has already been opened, we would like > >to get a bit more testing in before we hand it over to Linus. > > That seems like a good plan. Should we mark dynamic ftrace as X86 only > in Kconfig for .28 to prevent people from inadvertently setting it? Well, we probably should disable it for PPC at least. I don't know if sparc has the same issue. David? -- Steve -- 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/