Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754048AbZFHINr (ORCPT ); Mon, 8 Jun 2009 04:13:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753165AbZFHINc (ORCPT ); Mon, 8 Jun 2009 04:13:32 -0400 Received: from hera.kernel.org ([140.211.167.34]:43808 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752897AbZFHINa (ORCPT ); Mon, 8 Jun 2009 04:13:30 -0400 Date: Mon, 8 Jun 2009 08:12:52 GMT From: tip-bot for Dave Young To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, hidave.darkstar@gmail.com, hpa@zytor.com, mingo@redhat.com, torvalds@linux-foundation.org, akpm@linux-foundation.org, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, hidave.darkstar@gmail.com, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, torvalds@linux-foundation.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: References: Subject: [tip:core/printk] printk: Add halt_delay= parameter for printk delay in halt phase Message-ID: Git-Commit-ID: f43a6b1611aff688e21f323b64b98b57f8b7f721 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Mon, 08 Jun 2009 08:12:53 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3161 Lines: 91 Commit-ID: f43a6b1611aff688e21f323b64b98b57f8b7f721 Gitweb: http://git.kernel.org/tip/f43a6b1611aff688e21f323b64b98b57f8b7f721 Author: Dave Young AuthorDate: Mon, 8 Jun 2009 15:40:07 +0800 Committer: Ingo Molnar CommitDate: Mon, 8 Jun 2009 10:10:34 +0200 printk: Add halt_delay= parameter for printk delay in halt phase Add a halt_delay module parameter in printk.c used to read the printk messages in halt/poweroff/restart phase, delay each printk messages by halt_delay milliseconds. It is useful for debugging if there's no other way to dump kernel messages at that time. (if a system has no serial port - and if netconsole has already gone down at that stage where the messages are printed.) The halt_delay max value is 65535, default value is 0. To add a halt-day of 10 seconds, change it by: echo 10000 > /sys/module/printk/parameters/halt_delay Signed-off-by: Dave Young Cc: Andrew Morton Cc: Linus Torvalds LKML-Reference: Signed-off-by: Ingo Molnar --- Documentation/kernel-parameters.txt | 5 +++++ kernel/printk.c | 17 +++++++++++++++++ 2 files changed, 22 insertions(+), 0 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 6172e43..0630428 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1847,6 +1847,11 @@ and is between 256 and 4096 characters. It is defined in the file printk.time= Show timing data prefixed to each printk message line Format: (1/Y/y=enable, 0/N/n=disable) + printk.halt_delay= + Milliseconds to delay each printk during + halt/poweroff/restart phase. + Format: + processor.max_cstate= [HW,ACPI] Limit processor to maximum C-state max_cstate=9 overrides any DMI blacklist limit. diff --git a/kernel/printk.c b/kernel/printk.c index 5052b54..2114231 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -250,6 +250,22 @@ static inline void boot_delay_msec(void) } #endif +/* msecs delay after each halt/poweroff/restart phase printk, + unsigned short is enough for delay in milliseconds */ +static unsigned short halt_delay; + +static inline void halt_delay_msec(void) +{ + if (unlikely(halt_delay == 0 || !(system_state == SYSTEM_HALT + || system_state == SYSTEM_POWER_OFF + || system_state == SYSTEM_RESTART))) + return; + + mdelay(halt_delay); +} + +module_param(halt_delay, ushort, S_IRUGO | S_IWUSR); + /* * Commands to do_syslog: * @@ -649,6 +665,7 @@ asmlinkage int vprintk(const char *fmt, va_list args) char *p; boot_delay_msec(); + halt_delay_msec(); preempt_disable(); /* This stops the holder of console_sem just where we want him */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/