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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 6981FC10F27 for ; Tue, 10 Mar 2020 17:06:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3BB9420578 for ; Tue, 10 Mar 2020 17:06:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jLYLMbu4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726508AbgCJRGK (ORCPT ); Tue, 10 Mar 2020 13:06:10 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:37518 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726295AbgCJRGK (ORCPT ); Tue, 10 Mar 2020 13:06:10 -0400 Received: by mail-wr1-f67.google.com with SMTP id 6so16875284wre.4 for ; Tue, 10 Mar 2020 10:06:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=jHSzPIe7UkE4oaeuz7UEqGgpY9qJ5SXsYj5E9ovROlU=; b=jLYLMbu4ovc8dFtuvtpbsZ8vrzkv7KsQZeesJlhV1atV4rHATPTIHvzkQNbL7hfT9D mW6mdpg3ZxnpTTwgQLKxXxdlJyKa4vRUhHbS0p836hUtemMt2Eu8o2sSIDNZ372n9qg3 w0Suw1j6M+MK/gdnpfwzCVWovw603cqHUncDD9XC6fFnIhwBSBzn+tg/1RzikmVqIjUi 2HNw8UC2SZ5r+VA3U9tt/XgNqEQidZdxAXT4BqEMGSJrXuCqdO2krXl4SbAuJ2shwR6Q jk6MzDvWiSo6C5eCwROvt10hH9evS/kf62G7uqhCmGJ96zkaTNXUh/NZK3QG2JAHlkOP Sk5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=jHSzPIe7UkE4oaeuz7UEqGgpY9qJ5SXsYj5E9ovROlU=; b=psa5iLG7PD1rjzpHHcdl44hCrJQT7Q6sstPSsK2LBFO1dtC44RaU2g2vpabnxJdS6u OikwNSm5p4ehmNMCUsXRqXadOvDt1kIEpHjxYycZX9A6tiAR6duvPJVIytd7jWspNmKV tMZ6OV6Hhiy25ANomthkWj6NLnVEczpVOTKSoUkLT56JByPlV/HozFu5NP6+0SNCilB6 2+01YlaYHf7maheTMOTrDTO0ewKRadBYHanQSdVLSoR3GOu/yuyHPGTX8VhtRM48uKYo 6tlvBhZyt4K87MMoMbC9p/70nG84mPDoyIQSeg6HuMEdEAL6gShXi5Gk1aClb4t4PoSZ iYCQ== X-Gm-Message-State: ANhLgQ1HhUPJm/gHspnIbYcklfyF+8wGGL8rpEH6YqlC87i4n5+AKP/a 3tzoagrmDe1Ft90DRqVg6zU= X-Google-Smtp-Source: ADFU+vvu5URQoahAi/lxDIKNpLYdwqyogr6E1XxqEPO0o2j8Y9P0DqAPJEdKeBAqeeioVpCPgHRexQ== X-Received: by 2002:adf:fad0:: with SMTP id a16mr1794591wrs.119.1583859968494; Tue, 10 Mar 2020 10:06:08 -0700 (PDT) Received: from [10.83.36.153] ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id l83sm4986852wmf.43.2020.03.10.10.06.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 10 Mar 2020 10:06:07 -0700 (PDT) Subject: Re: [PATCH v1 1/4] serial: core: Use string length for SysRq magic sequence To: Andy Shevchenko Cc: Greg Kroah-Hartman , linux-serial@vger.kernel.org References: <20200310132004.86367-1-andriy.shevchenko@linux.intel.com> <64f650b7-8c39-4bef-f1d9-ff2720923c8c@gmail.com> <20200310145706.GQ1922688@smile.fi.intel.com> <20200310164851.GT1922688@smile.fi.intel.com> From: Dmitry Safonov <0x7f454c46@gmail.com> Message-ID: <11b21afc-fbd8-a148-de69-077fcbc928fa@gmail.com> Date: Tue, 10 Mar 2020 17:06:02 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: <20200310164851.GT1922688@smile.fi.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On 3/10/20 4:48 PM, Andy Shevchenko wrote: > > Have you seen to the assembly? > > For me it seems that GCC is clever enough to precalc length for constant > literals. > > With default string (empty) there is no uart_sysrq_on() at all in the code. > > With "pqr" I see this function and in particular: > 621: be 03 00 00 00 mov $0x3,%esi > > With "pqrst" > > 621: be 05 00 00 00 mov $0x5,%esi > > (Note, I compiled entire series, that's why uart_sysrq_on() has strlen() in) Ah, that solves all worries I have. Thanks again, Dmitry