From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756203Ab1JTJXb (ORCPT ); Thu, 20 Oct 2011 05:23:31 -0400 Received: from mail-ww0-f44.google.com ([74.125.82.44]:48326 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751478Ab1JTJXa (ORCPT ); Thu, 20 Oct 2011 05:23:30 -0400 Message-ID: <4E9FE8C6.10402@gmail.com> Date: Thu, 20 Oct 2011 17:24:22 +0800 From: snakky.zhang@gmail.com User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.23) Gecko/20110921 Thunderbird/3.1.15 MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: Why BOOT_PRINTK_DELAY "may adversely affect SMP systems"? Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi experts, I noticed there is an kernel option called BOOT_PRINTK_DELAY and some warning messages in the Kconfig file as below: NOTE: Using this option may adversely affect SMP systems. I.e., processors other than the first one may not boot up. BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect what it believes to be lockup conditions. As my understanding, this do nothing but just let the very CPU loop for a while and shouldn't cause any affect on the boot process. So I can hardly understand WHY it may cause "processors other than the first one may not boot up"? If this issue can be avoid/fixed? Thanks a lot! Snakky