Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752763AbYJTQao (ORCPT ); Mon, 20 Oct 2008 12:30:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751948AbYJTQag (ORCPT ); Mon, 20 Oct 2008 12:30:36 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.125]:64939 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751857AbYJTQaf (ORCPT ); Mon, 20 Oct 2008 12:30:35 -0400 Date: Mon, 20 Oct 2008 12:30:33 -0400 (EDT) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Josh Boyer cc: Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, David Miller , linuxppc-dev@ozlabs.org, Thomas Gleixner , Andrew Morton Subject: Re: [PATCH 0/2] ftrace: fixes for PPC In-Reply-To: <20081016150106.6ddf7e46@zod.rchland.ibm.com> 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> 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: 1844 Lines: 44 On Thu, 16 Oct 2008, Josh Boyer wrote: > > > > On Thu, 16 Oct 2008, Josh Boyer wrote: > > > > > > Well, that's why I asked. You sent 2 patches out over a month ago that > > > don't appear to have shown up in any Linus or PowerPC tree. > > > > Oh, the patches I sent on here, are not to solve this issue. It was > > actually solving issues in linux-tip itself. > > Totally confused as to what linux-tip is, but ok. > > > I'm still looking into the cause for ftrace not to boot on PPC. > > There were issues with -pg and some other compile flag on PPC at one > point. I think you worked that out with Ben, but I don't recall. > > 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. 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. -- 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/