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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7642DC433EF for ; Mon, 13 Jun 2022 18:59:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345231AbiFMS7V convert rfc822-to-8bit (ORCPT ); Mon, 13 Jun 2022 14:59:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43852 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346492AbiFMS6m (ORCPT ); Mon, 13 Jun 2022 14:58:42 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.85.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id AFFBF8CCD6 for ; Mon, 13 Jun 2022 09:11:30 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-188-UKF4EeJcNpOg5PEFD63RQQ-1; Mon, 13 Jun 2022 17:11:24 +0100 X-MC-Unique: UKF4EeJcNpOg5PEFD63RQQ-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) by AcuMS.aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) with Microsoft SMTP Server (TLS) id 15.0.1497.36; Mon, 13 Jun 2022 17:11:19 +0100 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.036; Mon, 13 Jun 2022 17:11:19 +0100 From: David Laight To: 'Petr Mladek' , Sergey Senozhatsky CC: John Ogness , Peter Geis , Linux Kernel Mailing List , "open list:ARM/Rockchip SoC..." Subject: RE: [BUG] Threaded printk breaks early debugging Thread-Topic: [BUG] Threaded printk breaks early debugging Thread-Index: AQHYfw5tEBAMEt7XXEKQmWQ8WlSw2q1Nf9Zw Date: Mon, 13 Jun 2022 16:11:19 +0000 Message-ID: References: <87y1y48spg.fsf@jogness.linutronix.de> <8735g9mqo0.fsf@jogness.linutronix.de> <87wndlge43.fsf@jogness.linutronix.de> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Petr Mladek > Sent: 13 June 2022 11:14 ... > Another interesting alternative is the Peter Zijlstra's mode > where all messages are printed to the console "immediately". > They are serialized only by the CPU-reentrant lock. > > This mode is not good for production system. But it might > be good for debugging. The good thing is that the behavior > is well defined. ISTM that all messages should be output (even if this means that cpu spin waiting for a serial console) until userspace has a chance to set an option to change the behaviour. Oh, and can someone stop the distros hiding the console output. I want to see the 'oops' traceback when I break the kernel! David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)