Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753534AbZFHH3i (ORCPT ); Mon, 8 Jun 2009 03:29:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753254AbZFHH3a (ORCPT ); Mon, 8 Jun 2009 03:29:30 -0400 Received: from mail-fx0-f213.google.com ([209.85.220.213]:35920 "EHLO mail-fx0-f213.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750918AbZFHH3a convert rfc822-to-8bit (ORCPT ); Mon, 8 Jun 2009 03:29:30 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=Vmm+W+FA8vqdvvjkWdSq+TI6SE1caeqK+fcwcMsbg+cj8JGyjK4bGgREmJvfFbze5C mhKNZxKTWi2A1z5I6QJbajHVzmcbRC12hQ/I8MNeeHnP5EIN1KNMYp/Ha8XQbbO+lA3X 7k5HW3Fvh+L2+or5JDVZ/RteGrwA+y6bIhcg4= MIME-Version: 1.0 In-Reply-To: <20090607143221.GE21340@elte.hu> References: <20090607143221.GE21340@elte.hu> Date: Mon, 8 Jun 2009 15:29:30 +0800 Message-ID: Subject: Re: [PATCH v2] printk: add halt_delay parameter for printk delay in halt phase From: Dave Young To: Ingo Molnar Cc: Linux Kernel Mailing List , Andrew Morton , Linus Torvalds Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2227 Lines: 73 On Sun, Jun 7, 2009 at 10:32 PM, Ingo Molnar wrote: > > * Dave Young wrote: > >> 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 */ > > Looks nice now - but please also add a description to > Documentation/kernel-parameters.txt. Oops, will add in v3 > > Thanks, > >        Ingo > -- Regards dave -- 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/