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 9D37EC433EF for ; Fri, 25 Feb 2022 06:12:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237484AbiBYGNN convert rfc822-to-8bit (ORCPT ); Fri, 25 Feb 2022 01:13:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231511AbiBYGNM (ORCPT ); Fri, 25 Feb 2022 01:13:12 -0500 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5C1EA172E5E for ; Thu, 24 Feb 2022 22:12:40 -0800 (PST) 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-147-A1-nNgw5OU26roG4mbNyRw-1; Fri, 25 Feb 2022 06:12:37 +0000 X-MC-Unique: A1-nNgw5OU26roG4mbNyRw-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 15.0.1497.28; Fri, 25 Feb 2022 06:12:35 +0000 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.028; Fri, 25 Feb 2022 06:12:35 +0000 From: David Laight To: 'Steven Rostedt' , LKML CC: Petr Mladek , Sergey Senozhatsky , John Ogness Subject: RE: Strange output on the console Thread-Topic: Strange output on the console Thread-Index: AQHYKfxF0QTTTto/+k+8VsyEcwRQo6yjyM1g Date: Fri, 25 Feb 2022 06:12:35 +0000 Message-ID: <61226fc12ff9459d8daed8e346d6ab94@AcuMS.aculab.com> References: <20220224230035.36547137@gandalf.local.home> In-Reply-To: <20220224230035.36547137@gandalf.local.home> 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: Steven Rostedt > Sent: 25 February 2022 04:01 > > I've been noticing that my tests have been spitting out strange output on > the console. It would happen at boot up and then clear up. It looks like > something screwed up with the serial timing. > > Attached is a dmesg of one of my test runs as an example. > > I've noticed this on both 32 bit and 64 bit x86. > > I haven't had time to look deeper into this, but I figured I let you know > about it. > > And it always seems to happen right after: > > Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled > > Maybe this is a serial issue and not a printk one? :-/ Looks very much like the serial baud rate is being reset. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)