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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 8BBB8C83000 for ; Tue, 28 Apr 2020 18:47:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 64B9020575 for ; Tue, 28 Apr 2020 18:47:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731003AbgD1Slf (ORCPT ); Tue, 28 Apr 2020 14:41:35 -0400 Received: from ms.lwn.net ([45.79.88.28]:41422 "EHLO ms.lwn.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730995AbgD1Sle (ORCPT ); Tue, 28 Apr 2020 14:41:34 -0400 Received: from lwn.net (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ms.lwn.net (Postfix) with ESMTPSA id 47A0744A; Tue, 28 Apr 2020 18:41:34 +0000 (UTC) Date: Tue, 28 Apr 2020 12:41:33 -0600 From: Jonathan Corbet To: Stephen Kitt Cc: Mauro Carvalho Chehab , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Steven Rostedt Subject: Re: [PATCH 2/3] docs: sysctl/kernel: document ftrace entries Message-ID: <20200428124133.0fbaf7c5@lwn.net> In-Reply-To: <20200423183651.15365-2-steve@sk2.org> References: <20200423183651.15365-1-steve@sk2.org> <20200423183651.15365-2-steve@sk2.org> Organization: LWN.net MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Thu, 23 Apr 2020 20:36:50 +0200 Stephen Kitt wrote: > Based on the ftrace documentation, the tp_printk boot parameter > documentation, and the implementation in kernel/trace/trace.c. > > Signed-off-by: Stephen Kitt This one could benefit from an ack from Steve (CC'd). Also one other little nit below: > Documentation/admin-guide/sysctl/kernel.rst | 50 +++++++++++++++++++++ > 1 file changed, 50 insertions(+) > > diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst > index 82bfd5892663..d4bbdaf96ebc 100644 > --- a/Documentation/admin-guide/sysctl/kernel.rst > +++ b/Documentation/admin-guide/sysctl/kernel.rst > @@ -265,6 +265,27 @@ domain names are in general different. For a detailed discussion > see the ``hostname(1)`` man page. > > > +ftrace_dump_on_oops > +=================== > + > +Determines whether ``ftrace_dump()`` should be called on an oops (or > +kernel panic). This will output the contents of the ftrace buffers to > +the console. This is very useful for capturing traces that lead to > +crashes and outputing it to a serial console. > + > += =================================================== > +0 Disabled (default). > +1 Dump buffers of all CPUs. > +2 Dump the buffer of the CPU that triggered the oops. > += =================================================== > + > + > +ftrace_enabled, stack_tracer_enabled > +==================================== > + > +See :doc:`/trace/ftrace`. > + > + > hardlockup_all_cpu_backtrace > ============================ > > @@ -1191,6 +1212,35 @@ If a value outside of this range is written to ``threads-max`` an > ``EINVAL`` error occurs. > > > +traceoff_on_warning > +=================== > + > +When set, disables tracing (see :doc:`/trace/ftrace`) when a > +``WARN()`` is hit. > + > + > +tracepoint_printk > +================= > + > +When tracepoints are sent to printk() (enabled by the ``tp_printk`` > +boot parameter), this entry provides runtime control:: > + > + echo 0 > /proc/sys/kernel/tracepoint_printk > + > +will stop tracepoints from being sent to printk(), and > + > +:: I would just make that ", and::" and avoid the separate line. > + > + echo 1 > /proc/sys/kernel/tracepoint_printk > + > +will send them to printk() again. > + > +This only works if the kernel was booted with ``tp_printk`` enabled. > + > +See :doc:`/admin-guide/kernel-parameters` and > +:doc:`/trace/boottime-trace`. > + > + > unknown_nmi_panic > ================= > Thanks, jon