Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755108AbZFCDJd (ORCPT ); Tue, 2 Jun 2009 23:09:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752583AbZFCDJ0 (ORCPT ); Tue, 2 Jun 2009 23:09:26 -0400 Received: from mail-pz0-f109.google.com ([209.85.222.109]:50430 "EHLO mail-pz0-f109.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752315AbZFCDJZ (ORCPT ); Tue, 2 Jun 2009 23:09:25 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:date:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=nLZvH4qQkd9XSf1jlmIX5w9a1tZrHSEomRiR+Tq4QwLSVLvygrgls0sqhFn5nRUOt3 T1jyn0h7iM4iv1wVADfzUB3GMEFJfCJeaP0OTn84DYGaZLmhq4OA+Fgj2S2wBJW9lMV9 BmEwhc5Cz+TEPZHgEUh6jc1Ynn6pdMjfQL4w4= MIME-Version: 1.0 Date: Wed, 3 Jun 2009 11:09:27 +0800 Message-ID: Subject: [PATCH v2] printk: add halt_delay parameter for printk delay in halt phase From: Dave Young To: Linux Kernel Mailing List Cc: Ingo Molnar Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1646 Lines: 52 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 that time. The halt_delay max value is 65535, default value is 0, change it by: echo xxx > /sys/module/printk/parameters/halt_delay Signed-off-by: Dave Young --- kernel/printk.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) --- linux-2.6.orig/kernel/printk.c 2009-06-03 10:16:55.000000000 +0800 +++ linux-2.6/kernel/printk.c 2009-06-03 10:32:43.000000000 +0800 @@ -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, 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/