From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtprelay.hostedemail.com (smtprelay0024.hostedemail.com [216.40.44.24]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id E2CA61A0065 for ; Sat, 6 Feb 2016 01:48:08 +1100 (AEDT) Date: Fri, 5 Feb 2016 09:48:03 -0500 From: Steven Rostedt To: Petr Mladek Cc: Torsten Duwe , Michael Ellerman , Jiri Kosina , Miroslav Benes , Jessica Yu , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org Subject: Re: [PATCH v7 04/10] ppc64 ftrace_with_regs configuration variables Message-ID: <20160205094803.1e0c6c91@gandalf.local.home> In-Reply-To: <20160205140517.GE3305@pathway.suse.cz> References: <20160204161527.5F3AC692CD@newverein.lst.de> <20160204162053.C76A7692D8@newverein.lst.de> <20160205140517.GE3305@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 5 Feb 2016 15:05:17 +0100 Petr Mladek wrote: > On Mon 2016-01-25 16:29:54, Torsten Duwe wrote: > > diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c > > index ef8b916..29b7014 100644 > > --- a/arch/powerpc/kernel/ftrace.c > > +++ b/arch/powerpc/kernel/ftrace.c > > @@ -28,6 +28,11 @@ > > > > > > #ifdef CONFIG_DYNAMIC_FTRACE > > +#if defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && defined(CONFIG_PPC64) && \ > > + !defined(CC_USING_MPROFILE_KERNEL) > > +#error "DYNAMIC_FTRACE_WITH_REGS requires working -mprofile-kernel" > > +#endif > > CONFIG_DYNAMIC_FTRACE_WITH_REGS is automatically enabled when > both CONFIG_DYNAMIC_FTRACE and HAVE_DYNAMIC_FTRACE_WITH_REGS > are enabled. > > Therefore it is not possible to build kernel with broken gcc > and DYNAMIC_FTRACE. > > IMHO, we need to allow to explicitely disable DYNAMIC_FTRACE_WITH_REGS > if the compiler is broken to get around this build error. > > We either need to define DYNAMIC_FTRACE_WITH_REGS as a proper > bool with description, help text, ... Or we need a way to > explicitely disable HAVE_DYNAMIC_FTRACE_WITH_REGS. Or something > like this. > You mean something like this? (not tested) -- Steve diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index e45db6b0d878..19377bacebfc 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -470,6 +470,19 @@ config DYNAMIC_FTRACE_WITH_REGS def_bool y depends on DYNAMIC_FTRACE depends on HAVE_DYNAMIC_FTRACE_WITH_REGS + depends on !DISABLE_DYNAMIC_FTRACE_WITH_REGS + +config DISABLE_DYNAMIC_FTRACE_WITH_REGS + bool "Force build to not have function tracer pass in registers" + depends on DYNAMIC_FTRACE + depends on HAVE_DYNAMIC_FTRACE_WITH_REGS + help + If the architecture supports passing in registers to the function + tracer, then that is automatically enabled. But there may be some + compilers out there that are broken and cause this to fail. + This option makes the build think that the architecture does not + support the register passing and allows the build to work even + with compilers that do not support the feature.g config FUNCTION_PROFILER bool "Kernel function profiler"