From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7AFC836084; Thu, 21 Dec 2023 16:52:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="MkvCD1lp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC9A7C433C7; Thu, 21 Dec 2023 16:52:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1703177578; bh=2+C30gWO9p+ECh2eEqgi3YMGW3elp4Wbdj+pcgG1FBI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MkvCD1lpEQS74u2K836Sk31wiPKIQVzOWS5vpSl+Zkdn7Vx2NZVJcMHIAHbA3abY5 T2kMc6++tN+4GEYP/fztYD0BNGwu2Vm7e7OBoZ/drb1fRqBLKEgVuM1S9xQL2IbJmR Bjpa12kBkWa/68K84LeCkrqg5iyjujzcpTDdwOJc= Date: Thu, 21 Dec 2023 17:52:55 +0100 From: Greg KH To: Sreenath Vijayan Cc: linux-doc@vger.kernel.org, linux-serial@vger.kernel.org, corbet@lwn.net, jirislaby@kernel.org, linux-kernel@vger.kernel.org, anandakumar.balasubramaniam@sony.com, Shimoyashiki Taichi Subject: Re: [PATCH] tty/sysrq: Dump kernel ring buffer messages via sysrq Message-ID: <2023122144-enlarged-maggot-493a@gregkh> References: <20231221133953.1507021-1-sreenath.vijayan@sony.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231221133953.1507021-1-sreenath.vijayan@sony.com> 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 :(