From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756839AbZANCvN (ORCPT ); Tue, 13 Jan 2009 21:51:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751762AbZANCu0 (ORCPT ); Tue, 13 Jan 2009 21:50:26 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:49644 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1755255AbZANCuW (ORCPT ); Tue, 13 Jan 2009 21:50:22 -0500 Message-ID: <496D52D4.70202@cn.fujitsu.com> Date: Wed, 14 Jan 2009 10:49:56 +0800 From: Lai Jiangshan User-Agent: Thunderbird 2.0.0.19 (Windows/20081209) MIME-Version: 1.0 To: Jason Baron CC: Ingo Molnar , Steven Rostedt , Linux Kernel Mailing List Subject: Re: [PATCH 4/5] ftrace: show ftrace_bprintk()'s formats References: <495ADF57.8030008@cn.fujitsu.com> <20090113231617.GD3210@redhat.com> In-Reply-To: <20090113231617.GD3210@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jason Baron wrote: > On Wed, Dec 31, 2008 at 10:56:23AM +0800, Lai Jiangshan wrote: >> Impact: let user knows the format >> >> Create a file on /tracing/ to show ftrace_bprintk()'s formats. >> >> This formats will help for these condition: >> 1) User get binary data from core file.(formats are backup before coredump) >> 2) User splice ring_buffer to a file. >> User can use formats for parsing the binary data in userspace. >> > > When I 'cat' trace_bprintk_formats on my system the file is empty. This > seems to be b/c 'ftrace_bprintk' is not being used in this patchset. It > can't be used in patch #5 during marker register b/c the format wouldn't > be known at runtime. Thus, as it currently stands this patch, patch 4/5, > isn't adding much? If you don't use ftrace_bprintk(), the file trace_bprintk_formats is empty. This file record all formats which ftrace_bprintk() uses. You can use ftrace_bprintk() everywhere as another printk(). Patch #5 enables binary printk for markers, this is another additional tool for tracing markers. > > A thought on how this might be resolved would be to have the core marker > code pass us its address so this could be recorded in the trace buffer. > Then, also add some debug file that displays the markers and maps marker > addresses with format strings. > Patch#5 does it as you said.