Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932464Ab2J3Pfm (ORCPT ); Tue, 30 Oct 2012 11:35:42 -0400 Received: from mail-lb0-f174.google.com ([209.85.217.174]:49178 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932135Ab2J3Pfk (ORCPT ); Tue, 30 Oct 2012 11:35:40 -0400 MIME-Version: 1.0 In-Reply-To: <1351609517.8467.85.camel@gandalf.local.home> References: <1351609517.8467.85.camel@gandalf.local.home> Date: Tue, 30 Oct 2012 15:35:38 +0000 Message-ID: Subject: Re: [PATCH] scripts/recordmcount.pl: Support build with -ffunction-sections. From: Will Newton To: Steven Rostedt Cc: Linux Kernel list Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1603 Lines: 39 On Tue, Oct 30, 2012 at 3:05 PM, Steven Rostedt wrote: > On Tue, 2012-10-30 at 14:51 +0000, Will Newton wrote: >> Scan any text section whose name begins with ".text." so >> we will find all the functions in a kernel built with >> -ffunction-sections. > > A couple of things. > > First, I'm very paranoid about a blanket "ok" on sections. We must > guarantee that all sections that starts with ".text" never is freed. And > if it is freed, that it must inform ftrace that it's about to free it > before it does. If we can not guarantee this, then we can't do it. I share that concern, however it looks like it should be safe. The two architectures in tree that enable -ffunction-sections by default are parisc and score and they both use a .text.* wildcard in their linker script. If the support for building with --gc-sections is ever completed then that would require -ffunction-sections and a similar wildcard to be applied to section names. > Second, most archs today do not use recordmcount.pl. They use the new > recordmcount.c file. Ok, thanks for letting me know. Is the plan to switch over to recordmcount.c exclusively at some point? The following architectures have some support in recordmcount.c but do not enable it: sh, powerpc, ia64 And the following have no support in recordmcount.c as yet: blackfin, microblaze -- 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/