From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f49.google.com (mail-ej1-f49.google.com [209.85.218.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 954CC6CDA3 for ; Wed, 22 May 2024 15:31:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.49 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716391877; cv=none; b=OW76O2GeHNYIbcPplFtgTWFUArgqEHJO/sAcG4rhLGAAjoHw2CVd0AgZEOR0ljM9o1tFQQYFnFsKwLg+3t2CsUCxJi/LJzi6KDGmo8UkYp++JlDkWwSnYHv1ds+FtDgqEOt56SGmTSweKMbaKBDNyacp1iFA/BsEoecSX3rp2fw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716391877; c=relaxed/simple; bh=DblYs+ScPiYd2IWFS83ByHnJTeIt6Z6vSH1U1R5ojrw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dTow7tzGdVYLauHUZX3NipmTji1zRdal3DR0GHGv/vBGEOK5W80TJ/0udgH5xJbaVL3BiPgwCIgvnu7RWcmTbxPVNqZxB44iG4LXGFbVd163zLEL0C3Iy8sbbVhRazz7nD3UCg6xfwoIoRQV+swgkep79Zdi/yudEl5MDS7yRHQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=ZybNjzWp; arc=none smtp.client-ip=209.85.218.49 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="ZybNjzWp" Received: by mail-ej1-f49.google.com with SMTP id a640c23a62f3a-a59cdd185b9so221341466b.1 for ; Wed, 22 May 2024 08:31:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1716391874; x=1716996674; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=iOnW/DfLA3xJXZ5u+WZq3O9RUUMYHYU/muej88lDrWk=; b=ZybNjzWp/+wwasCT5weeIL7CIV9zPVbn/53q2/YeEdPzrRjUVaUi6s0hooWjaQLh57 ACf3NUu8vvJM+BtTMi3VwOKEaH8/xzva6JDJhFguY2xOMmQkWY8mVSBuTJb8+kL3Ei1W QExy+8Tuw35gz8NEzePbjK1dM3BrB2q/Z+UR/BQ+r/jm5kYPftj0YT9d/Ur07hyGyh54 hI41sihIJIAG7qRRB0mU6h5b3pAP6phowMoKSrV/UTCd152tc2nq4KqRYI6/TqAoTCm/ 0KdqR8UQVKLk5iHuh57Z9UHegna2I+Y+MfgeiDBIb/jwskkZSqtLHNXTUXP/p3II5wyJ FsCQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1716391874; x=1716996674; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=iOnW/DfLA3xJXZ5u+WZq3O9RUUMYHYU/muej88lDrWk=; b=Knat1Q3GOLhoVTmHh5nczF6mi6XBne3RgkQ/qVn6llASOnHrPJMKJkOzOMg01ML4HH gtzVgFx6MaZViemFggGeaE+JzzI3jGNY9Ztd/fxmU4WGorYP9+4+Wg7m7uee1m6XB2T1 9m3TFqmBJF/wF7IbM/Aae01XUBnUEyiJDh3tz+q5ytSmP41jvQWiuF4YxWSoQFnQ1o7p B//TLYzs1HMc16WVie1RFbAgVj+aNqcwcIM9ln+a/EAjoqHP8Sh35erWxELda32Yyrru s607nTysq+wYiHHBIWNjoA9gunJWI88mwBHdUO9YxrapuPrg05b9zSNQOYIFv68/1Mgx 5Z9g== X-Forwarded-Encrypted: i=1; AJvYcCV5VuKpttod3CePJlEKyjfB8AfwXfRdhTaftvGgq5TRmkJuIsJz1YqHynLwerISDZGI1Uxw01H8dsPVsCZ9tDXK2jhkBtcW/e0mN5cr X-Gm-Message-State: AOJu0Yxa0xYM3AOwuczgVFLI0HOp1GxzsB8oY3KeU/dkQZS0glRa/UmW wvdCtGDOe1KjjB4uS4NKtzsgt1ZDMGNnv/ric0fmpljAiPTbCljDnxaEeShMj8g= X-Google-Smtp-Source: AGHT+IGqVvLYq+kT50O7GsSXXYDLUBYlTXLfwZdhz5s8zKLbBgML4M/AO44hf5zj4i1wkF2z2CAoEg== X-Received: by 2002:a17:906:3cea:b0:a59:9f88:f1f1 with SMTP id a640c23a62f3a-a622314c52dmr217055966b.19.1716391874015; Wed, 22 May 2024 08:31:14 -0700 (PDT) Received: from pathway.suse.cz ([176.114.240.50]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a5a17894d40sm1781965366b.75.2024.05.22.08.31.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 May 2024 08:31:13 -0700 (PDT) Date: Wed, 22 May 2024 17:31:12 +0200 From: Petr Mladek To: Sreenath Vijayan Cc: john.ogness@linutronix.de, corbet@lwn.net, gregkh@linuxfoundation.org, jirislaby@kernel.org, rdunlap@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, taichi.shimoyashiki@sony.com, daniel.palmer@sony.com, anandakumar.balasubramaniam@sony.com Subject: Re: [PATCH v6 2/2] tty/sysrq: Replay kernel log messages on consoles via sysrq Message-ID: References: Precedence: bulk X-Mailing-List: linux-serial@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: On Wed 2024-03-13 15:52:52, Sreenath Vijayan wrote: > When terminal is unresponsive, one cannot use dmesg to view > the printk ring buffer messages. Also, syslog services may be > disabled, especially on embedded systems, to check the messages > after a reboot. In this scenario, replay the messages in printk > ring buffer on consoles via sysrq by pressing sysrq+R. > > The console loglevel will determine which all kernel log messages > are displayed. The messages will be displayed only when > console_trylock() succeeds. Users could repeat the sysrq key when > it fails. If the owner of console subsystem lock is stuck, > repeating the key won't work. > > Suggested-by: Petr Mladek > Signed-off-by: Shimoyashiki Taichi > Reviewed-by: John Ogness > Signed-off-by: Sreenath Vijayan Reviewed-by: Petr Mladek Best Regards, Petr