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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_SANE_1 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 85276C433DF for ; Mon, 12 Oct 2020 15:10:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3FC5420878 for ; Mon, 12 Oct 2020 15:10:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389593AbgJLPKu (ORCPT ); Mon, 12 Oct 2020 11:10:50 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:45882 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389269AbgJLPKu (ORCPT ); Mon, 12 Oct 2020 11:10:50 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: gtucker) with ESMTPSA id 64D8B1F44AF0 Subject: Re: [PATCH] x86/x86_64_defconfig: Enable the serial console To: Willy Tarreau , Borislav Petkov Cc: Enric Balletbo i Serra , Randy Dunlap , linux-kernel@vger.kernel.org, x86@kernel.org, Collabora Kernel ML , Thomas Gleixner , Ingo Molnar , =?UTF-8?Q?Diego_Elio_Petten=c3=b2?= , "H. Peter Anvin" , "Martin K. Petersen" , Nathan Chancellor , kernelci@groups.io References: <20201008164044.GE5505@zn.tnic> <4162cfa4-7bf2-3e6e-1b8c-e19187e6fa10@infradead.org> <2538da14-0f4b-5d4a-c7bf-6fdb46ba2796@collabora.com> <20201011122020.GA15925@zn.tnic> <107a6fb0-a667-2f30-d1f4-640e3fee193a@collabora.com> <20201011155754.GC15925@zn.tnic> <1dfdf163-9b54-ceae-b178-c566e6109263@collabora.com> <20201012035846.GB11282@1wt.eu> <20201012143212.GC22829@zn.tnic> <20201012144040.GB11614@1wt.eu> From: Guillaume Tucker Message-ID: Date: Mon, 12 Oct 2020 16:10:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 MIME-Version: 1.0 In-Reply-To: <20201012144040.GB11614@1wt.eu> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/10/2020 15:40, Willy Tarreau wrote: > On Mon, Oct 12, 2020 at 04:32:12PM +0200, Borislav Petkov wrote: >> On Mon, Oct 12, 2020 at 11:22:10AM +0100, Guillaume Tucker wrote: >>> However, it was found while adding some x86 Chromebooks[1] to >>> KernelCI that x86_64_defconfig lacked some basic things for >>> anyone to be able to boot a kernel with a serial console enabled >>> on those. >> >> Hold on, those are laptops, right? How come they do have serial console? >> Because laptops don't have serial console - that has been the eternal >> problem with debugging kernels on laptops. Yes the link you pointed at is a prerequisite to enable serial console in the firmware (Coreboot/Depthcharge). > Well, to be precise, they don't have *anymore*. I used to exclusively > select laptops having a serial port given that I was using it daily with > routers, until I had to resign when I abandonned my good old NC8000 :-/ You can get serial console on recent enough Chromebooks with a debug interface such as SuzyQable: https://www.sparkfun.com/products/14746 It's not a USB Type-C adapter, it has a debug interface which works with Chromebooks that support Case-Closed Debugging. Anyone can do that without modifying the Chromebook, and with a bit of patience to go through the documentation[1]... The KernelCI sample results from my previous email were run using just that: off-the-shelf Chromebooks + SuzyQ + rebuilt firmware for interactive console and tftp boot + kernel with the config options in Enric's patch. Thanks, Guillaume [1] https://chromium.googlesource.com/chromiumos/platform/ec/+/cr50_stab/docs/case_closed_debugging_cr50.md