From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754178Ab1JJNRJ (ORCPT ); Mon, 10 Oct 2011 09:17:09 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:34349 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753028Ab1JJNRH (ORCPT ); Mon, 10 Oct 2011 09:17:07 -0400 X-Authority-Analysis: v=1.1 cv=XWD5/VRj2HUJOhsR8cgmvPBlhMACpZXxseY1Kn/ehQI= c=1 sm=0 a=Vdgllb604mQA:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=ZycB6UtQUfgMyuk2+PxD7w==:17 a=lzU3S89KWSta-HUlvxEA:9 a=PUjeQqilurYA:10 a=ZycB6UtQUfgMyuk2+PxD7w==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.80.29 Subject: Re: [PATCH 2/3][RFC] tracing: Add optional percpu buffers for trace_printk() From: Steven Rostedt To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Thomas Gleixner , Frederic Weisbecker Date: Mon, 10 Oct 2011 09:17:05 -0400 In-Reply-To: <1318251873.14400.30.camel@laptop> References: <20111008170227.792806635@goodmis.org> <20111008171259.462646120@goodmis.org> <1318244913.14400.19.camel@laptop> <1318250240.7904.74.camel@gandalf.stny.rr.com> <1318251873.14400.30.camel@laptop> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.0.3- Content-Transfer-Encoding: 7bit Message-ID: <1318252626.7904.85.camel@gandalf.stny.rr.com> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2011-10-10 at 15:04 +0200, Peter Zijlstra wrote: > On Mon, 2011-10-10 at 08:37 -0400, Steven Rostedt wrote: > > > This will make debugging some of my embedded boards difficult (the ones > > where I have no way to add kernel command lines). If there's a problem > > at boot up, I will have to modify the kernel to get this to print. > > > > For those that don't know the tracing code, it will just simply break. > > > > Unless you want me to keep the kconfig option that enables it > > permanently. Then I could do this. > > There's a fairly easy fix for that, initialize it at boot, and free once > userspace it up and running if no trace_printk() came by. Hmm, I could do that. Of course this will add a check for a global variable in all trace_printks. I could make it a read_mostly variable, as it only gets updated once, or even encapsulate the entire check with a static_switch() :) > > > I also expect tglx to throw frozen sharks at me for "why doesn't > > trace_printk() work anymore?!!!!" > > I'm sure you'll get over that :-) I've had too many, I'm not sure my head could take much more. -- Steve