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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 219FAC3A5A9 for ; Mon, 4 May 2020 19:30:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F22BB20705 for ; Mon, 4 May 2020 19:30:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="T5FiPtGv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726441AbgEDTau (ORCPT ); Mon, 4 May 2020 15:30:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42970 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726291AbgEDTau (ORCPT ); Mon, 4 May 2020 15:30:50 -0400 Received: from mail-pj1-x1044.google.com (mail-pj1-x1044.google.com [IPv6:2607:f8b0:4864:20::1044]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF3F1C061A0E for ; Mon, 4 May 2020 12:30:49 -0700 (PDT) Received: by mail-pj1-x1044.google.com with SMTP id t9so387879pjw.0 for ; Mon, 04 May 2020 12:30:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=GvLvZU44cktGvErQTqiBjoj1iPW+UBXunAz14YrNO9c=; b=T5FiPtGvZMFrbUZk/4iBuNfw+RFpSJl6HUKnfq+wHH1++wYlpZz4hqvvAePrDhQQ6s Vck1ldqrkjru5SeI1/td7byouT12Qkww1IE98DHrTD4UZ+NcWdPRHFGl5g+jqtH4C7CX 545i33PZ2/G0mSQECOFrrV+P80qGRg5XCAqRU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=GvLvZU44cktGvErQTqiBjoj1iPW+UBXunAz14YrNO9c=; b=ePrCS5vsaH+CGtMs34BDd7j03iWpv2KAVl2BzyVrSs3+vO8OU3kjCBB/qwC829HpW+ eIXXD9tI/l7IYIPN6bCvCNRWIG9VvfneJtRZ40FJ5xPFTYhGd6sZ10DGik49PheL5zaQ hYbQtH1uPfujqWYEy2dPEiFuSV1nfHMtgeIMSw2irXCaxmWLZ6M+nGx25AiZ/lOV61q8 6bxvPAxU2al1Sc8aGfaQjYLcL+oW80YSsgRG+qvArEheRSBzyL5i8rME92qdQUHFt4X0 f7oi+t1kZnF6aqKh6u0b7ununOdnEVZIsDHMjtYookAy6IsWr0E38e/J7zqMhdRpvxut +rGA== X-Gm-Message-State: AGi0PuZOLRJgVmmmEk6wpZb5t8VMFdkV825EHtAX/JvVIAtVnlV5q1mI lu8wF2NXma7cckr87eItiICzyg== X-Google-Smtp-Source: APiQypJkNruhH47ZJCVEHc7eoKaadBx0p15GdanZfiVN4hm+8f5QavcGQgO6r0fQPqFuGhCiYa49Kg== X-Received: by 2002:a17:90b:b06:: with SMTP id bf6mr570061pjb.179.1588620649478; Mon, 04 May 2020 12:30:49 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id i10sm9256813pfa.166.2020.05.04.12.30.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 May 2020 12:30:48 -0700 (PDT) Date: Mon, 4 May 2020 12:30:47 -0700 From: Kees Cook To: Pavel Tatashin Cc: James Morris , Sasha Levin , LKML , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , anton@enomsg.org, ccross@android.com, Tony Luck , robh+dt@kernel.org, devicetree@vger.kernel.org Subject: Re: [PATCH v1 0/3] allow ramoops to collect all kmesg_dump events Message-ID: <202005041230.806B1581D@keescook> References: <20200502143555.543636-1-pasha.tatashin@soleen.com> <202005041112.F3C8117F67@keescook> <202005041211.040A1C65C8@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Mon, May 04, 2020 at 03:17:40PM -0400, Pavel Tatashin wrote: > On Mon, May 4, 2020 at 3:12 PM Kees Cook wrote: > > > > On Mon, May 04, 2020 at 02:47:45PM -0400, Pavel Tatashin wrote: > > > > > # reboot -f > > > > > > > > > > After VM is back: > > > > > > > > > > # mount -t pstore pstore /mnt > > > > > # head /mnt/dmesg-ramoops-0 > > > > > Restart#1 Part1 > > > > > > > > Is there a reason that using ramoops.console_size isn't sufficient for > > > > this? > > > > > > Unfortunately, the console option is not working for us (Microsoft), > > > we have an embedded device with a serial console, and the baud rate > > > reduces the reboot performance, so we must keep the console quiet. We > > > also want to be able collect full shutdown logs from the field that > > > are collected during kexec based updates. > > > > I meant collecting console via pstore (i.e. /mnt/console-ramoops-0). Are > > you saying that's still too large for your situation? > > pstore /mnt/console-ramoops-0 outputs only messages below the console > loglevel, and our console loglevel is set to 3 due to slowness of > serial console. Which means only errors and worse types of messages > are recorded. AFAIK, there is no way to have different log levels for > different consoles. Ah-ha! Okay, thanks. Please include this rationale in the v2 changelog. That makes perfect sense; I just didn't see it and maybe others will need the same clarity too. Thanks! -Kees -- Kees Cook