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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 2294BC2BA19 for ; Tue, 14 Apr 2020 09:56:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C721E2064A for ; Tue, 14 Apr 2020 09:56:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="tEqsTplx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2438038AbgDNJ44 (ORCPT ); Tue, 14 Apr 2020 05:56:56 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:38846 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2437925AbgDNJ4z (ORCPT ); Tue, 14 Apr 2020 05:56:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=MFDKQod1ulWQsmUhrBi6caTSYw9k5n9WOUJXNnAw418=; b=tEqsTplxGA9kKYxzAAvY0u8Hp Tqqs3i+D3QDwd/qy/IELdE65zUz6p6RCDGbTemRf1hGmd+V+7UBx2VxP3sa1i4dSYCJNrmBqgkfiB vYbiajLZaDRY37lu2pObRfLM5rNmRad9BtuuY0WXKiCtw7iWpDvHaDreGfOfh4plY4K5A11M9g2up L+RrfIbLX2D320dt/uwiojhZFflNQ6vsi+o+/rTVp0Zh1NCIaNf1Oxc+EU80iQgMolTDk2DXwerR/ 8UQ4U6L2LzI8SC1soWDlQnm7iADCwfhBlWR82opdT2l8F6ZRJ+BnD2RjaRDm+fhwtBc0LzVav2R2t 7MQ4UPQ8Q==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:49896) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jOIJB-0007ES-OU; Tue, 14 Apr 2020 10:56:45 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1jOIJA-0007rs-6J; Tue, 14 Apr 2020 10:56:44 +0100 Date: Tue, 14 Apr 2020 10:56:44 +0100 From: Russell King - ARM Linux admin To: Sergey Organov Cc: Jiri Slaby , linux-serial@vger.kernel.org, Greg Kroah-Hartman Subject: Re: Serial console and interrupts latency. Message-ID: <20200414095644.GU25745@shell.armlinux.org.uk> References: <87lfnq15vi.fsf@osv.gnss.ru> <87ftdtzypi.fsf@osv.gnss.ru> <20200327232428.GT25745@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Tue, Apr 14, 2020 at 12:50:49PM +0300, Sergey Organov wrote: > Russell King - ARM Linux admin : > > Correct, and what I said back then still applies - and more. > > What bothers me is "we have no real option..." part of this, as it's rarely > happens to be the case. I don't see you coming forward with a solution beyond "let's revert the commit" or "let's comment out the lock" - neither of which are an option for mainline kernels. Until *you* do, since you obviously have better ideas, "we have no real option". But, as I've said, one of the *important* characteristics of serial console is that it is synchronous with the kernel, so it can be relied upon to get complete messages out if the kernel crashes after a printk() has been executed, and that must not be lost. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 10.2Mbps down 587kbps up