From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5C542C4727E for ; Tue, 22 Sep 2020 01:25:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2B25A23AAC for ; Tue, 22 Sep 2020 01:25:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729667AbgIVBZL (ORCPT ); Mon, 21 Sep 2020 21:25:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:56646 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729603AbgIVBYz (ORCPT ); Mon, 21 Sep 2020 21:24:55 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DB37123B16; Tue, 22 Sep 2020 01:24:54 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.94) (envelope-from ) id 1kKX37-001sSy-Ua; Mon, 21 Sep 2020 21:24:53 -0400 Message-ID: <20200922012453.807317415@goodmis.org> User-Agent: quilt/0.66 Date: Mon, 21 Sep 2020 21:24:40 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Masami Hiramatsu Subject: [for-next][PATCH 26/26] Documentation: tracing: Add the startup timing of boot-time tracing References: <20200922012414.115238201@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu Add the note about when to start the boot-time tracing. This will be needed for the people who wants to trace earlier boot sequence. Link: https://lkml.kernel.org/r/159974156678.478751.10215894815285734481.stgit@devnote2 Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- Documentation/trace/boottime-trace.rst | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/Documentation/trace/boottime-trace.rst b/Documentation/trace/boottime-trace.rst index ab3bfd67197c..89b64334929b 100644 --- a/Documentation/trace/boottime-trace.rst +++ b/Documentation/trace/boottime-trace.rst @@ -120,6 +120,20 @@ instance node, but those are also visible from other instances. So please take care for event name conflict. +When to Start +============= + +All boot-time tracing options starting with ``ftrace`` will be enabled at the +end of core_initcall. This means you can trace the events from postcore_initcall. +Most of the subsystems and architecture dependent drivers will be initialized +after that (arch_initcall or subsys_initcall). Thus, you can trace those with +boot-time tracing. +If you want to trace events before core_initcall, you can use the options +starting with ``kernel``. Some of them will be enabled eariler than the initcall +processing (for example,. ``kernel.ftrace=function`` and ``kernel.trace_event`` +will start before the initcall.) + + Examples ======== -- 2.28.0