From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) (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 BA4D43DB337; Wed, 5 Aug 2026 20:50:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.97.179.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785963054; cv=none; b=hln+vbKU0EteWrpahliEh0ppJbKKAS8mr3AaYHGlWatX42J+ZkCvi4Iu3d3ZLrTjwzzGoNQZTqblVIPIRi/2lASH3tU0aj3TV+cNd9aiS1slGWg3fBegLH/qVM/BBZCDfkuDlpOklMaYB4EH42n4FdxZWttiGgleXBDoG8bVMlA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785963054; c=relaxed/simple; bh=jBe5ah8o9BFimtdWRfixOgYgVUvf5xybporM2aY6A+8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ZQwkAH6oqzBP/zI1jRJkigaKiZ0Hbzyl2TuAlRZCt/PAa7C2RfnYGPGLLmfy1CV8HnpHPw1kEmn/qrq29DNBeWzyQ5mIoLhlqutibEJhXZ9ZUVt7wfQVd5erFBZ4F/6PC3RiVHrJlGsW8l0VXVVxIDlGIUP04qOhn+0RfGUCFQ4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=ijPCqiAp; arc=none smtp.client-ip=213.97.179.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="ijPCqiAp" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:Message-ID:Date:Subject: Cc:To:From:From:Reply-To; bh=hsDhM5GkTmS9ssjk/k/BNMufe9BdUo/SILJeWpEOq3w=; b= ijPCqiAp+AA/vvI2g11HaDLx+90m9q+2z9MsZHPs9m5s/UrHC5d5f50Y5TUeRT2Hy3ivlVCRB/Hri ky0wAUvCIfwryCJSHzv8DnoP9smff8n/bocaFGYBRXWeoyHEp42deNfCFlbegysErmPX9fUiEzxDW cRa+9w+UBHyIfb6FZU+b1vx/86mKMqtr+xk/hgtV9LXeQjC76yScYj+v1qmxyKcRUY3eLZPjK/MpA WvRAdEjfGzqbYWQXmO+INZgXc6JxcUhS4inwM/QUkmerYS3EUhZcH0PP8UnIW74/17lK31hNH5aBi 49ONwASMwToTnvUw96LFipSSQ9soQy+seQ==; Received: from [191.19.52.61] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1wriZT-00EcMc-Sd; Wed, 05 Aug 2026 22:50:40 +0200 From: "Guilherme G. Piccoli" To: linux-doc@vger.kernel.org Cc: corbet@lwn.net, skhan@linuxfoundation.org, rdunlap@infradead.org, feng.tang@linux.alibaba.com, andriy.shevchenko@linux.intel.com, kees@kernel.org, tony.luck@intel.com, pmladek@suse.com, linux-kernel@vger.kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, "Guilherme G. Piccoli" Subject: [PATCH] docs: panic: Disclaimer about console verbosity when using panic_print with pstore Date: Wed, 5 Aug 2026 17:49:04 -0300 Message-ID: <20260805205026.1699568-1-gpiccoli@igalia.com> X-Mailer: git-send-email 2.50.1 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Users of panic_print / panic_sys_info are usually aware of the potentially huge amount of information displayed with such options - their goal by using them is indeed to dump more information during panic! What might come unnoticed at first is the impact that the console_verbose() call on panic path has, specially in cases that users rely on pstore as a means to collect the panic logs. Recent experience shows that dumping all tasks in an ARM64 system (with qcom_geni tty driver) gets a 2 minute delay on panic time due to writing such information to console. But in that case, pstore was used, so there was no need for console printing, and suppressing that reduced the full time to less than 1 second. The option "printk.console_no_auto_verbose" aims exactly at this use case: avoid automatically increasing the loglevel during panic path. So, let's officially document this to avoid users wasting their time either on long panic printing or debugging the panic delays. Signed-off-by: Guilherme G. Piccoli --- Documentation/admin-guide/kernel-parameters.txt | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index b5493a7f8f22..04c0ef2cf910 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4862,6 +4862,9 @@ Kernel parameters so there are risks of losing older messages in the log. Use this option carefully, maybe worth to setup a bigger log buffer with "log_buf_len" along with this. + Also consider using "printk.console_no_auto_verbose=Y" + if using this along with pstore, to avoid extra delays + due to increased console verbosity during panic. panic_sys_info= A comma separated list of extra information to be dumped on panic. @@ -4877,6 +4880,8 @@ Kernel parameters blocked_tasks: print only tasks in uninterruptible (blocked) state This is a human readable alternative to the 'panic_print' option. + Please be aware of the caveats using this option, check + the panic_print information above regarding delays. panic_console_replay When panic happens, replay all kernel messages on -- 2.50.1