From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 529E12E821; Fri, 22 Dec 2023 19:43:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="qvUfuaMH" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Sender:Reply-To:Content-ID:Content-Description; bh=gKd+L66yod8uEFMOkkJsz50fKS7oNh0JqJUaQ5OiA70=; b=qvUfuaMHAQaYqMURVQygCfszfG 9QT7QwkPrtisjT+uboyWdYogLKeA6pEQo3JoPX45oIKIVjLOmnnENQS63rKdMoY4Gtzqpx8CjX4yp RYYJQFgtvBzHai73RMxlDyVNDKuiFnYPDo3vp9ttaHrIL1t11F+0A+qZh9AxZSFeQ9GVsO8g3tjkd JCpjmZ5m604zNxb3HgwF3ACgNIkopGDOqIAaiPIVm8jtkLOLt+AT/YNPRiZfUX2LocNmmCsznuxlg dSZ8/86tisux0kY54VR7z4KRr+GhuYMRE/4lOIAFbM63RIzaHG7EHcz6n/Ejfdipx9T1Eb9XbJE75 gzf9eHgQ==; Received: from [50.53.46.231] (helo=[192.168.254.15]) by bombadil.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1rGlQf-006kB4-0P; Fri, 22 Dec 2023 19:43:29 +0000 Message-ID: Date: Fri, 22 Dec 2023 11:43:28 -0800 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] tty/sysrq: Dump kernel ring buffer messages via sysrq Content-Language: en-US To: Sreenath Vijayan Cc: anandakumar.balasubramaniam@sony.com, corbet@lwn.net, gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, taichi.shimoyashiki@sony.com References: <20231222115732.1683728-3-sreenath.vijayan@sony.com> From: Randy Dunlap In-Reply-To: <20231222115732.1683728-3-sreenath.vijayan@sony.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 12/22/23 03:44, Sreenath Vijayan wrote: > On Thu, Dec 21, 2023 at 03:12:46PM -0800, Randy Dunlap wrote: >> >> >> On 12/21/23 08:52, Greg KH wrote: >>> On Thu, Dec 21, 2023 at 07:09:53PM +0530, Sreenath Vijayan wrote: >>>> When terminal is unresponsive, one cannot use dmesg to view kernel >>>> ring buffer messages. Also, syslog services may be disabled, >>>> to check them after a reboot, especially on embedded systems. >>>> In this scenario, dump the kernel ring buffer messages via sysrq >>>> by pressing sysrq+D. >>>> >>>> Signed-off-by: Sreenath Vijayan >>>> Signed-off-by: Shimoyashiki Taichi >>>> --- >>>> Documentation/admin-guide/sysrq.rst | 2 ++ >>>> drivers/tty/sysrq.c | 43 ++++++++++++++++++++++++++++- >>>> 2 files changed, 44 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst >>>> index 2f2e5bd440f9..464c4e138b9d 100644 >>>> --- a/Documentation/admin-guide/sysrq.rst >>>> +++ b/Documentation/admin-guide/sysrq.rst >>>> @@ -161,6 +161,8 @@ Command Function >>>> will be printed to your console. (``0``, for example would make >>>> it so that only emergency messages like PANICs or OOPSes would >>>> make it to your console.) >>>> + >>>> +``D`` Dump the kernel ring buffer >>>> =========== =================================================================== >>> >>> Nit, this doesn't line up anymore :( >> >> Yes, that will cause a docs build warning. > > Thank you for the review comments. When I apply the patch, I don't > notice any alignment issues in the document. I tried with multiple > editors(vim,emacs) and the combination of tabs and spaces looks to > be the same as in the existing lines above the newly added line. > Tried "make htmldocs" and no warnings were observed and the html > page looks ok. Please suggest the modifications to be done. You are correct. Sorry for the confusion. It can be messy trying to read/review a diff when there is alignment involved. >> >> Also, can you be more explicit about which ring buffer this patch >> is referring to, please. >> > > We see the term "kernel ring buffer" used throughout the documents > and commit messages, and thought it is the right term. Even dmesg > manual page uses it. Would "kernel log buffer" be a more appropriate > term? Please share your suggestion. Documentation/admin-guide/kernel-parameters.txt refers to: ftrace ring buffer printk ring buffer tracing ring buffer so saying "kernel ring buffer" is not very specific. I expect that you are referring to the printk ring buffer, although I would prefer to call it something like the console log buffer (FWIW). thanks. -- #Randy https://people.kernel.org/tglx/notes-about-netiquette https://subspace.kernel.org/etiquette.html