From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from prod-mail-xrelay07.akamai.com (prod-mail-xrelay07.akamai.com [72.246.2.115]) by ozlabs.org (Postfix) with ESMTP id 7C97E2C0099 for ; Wed, 20 Nov 2013 09:10:03 +1100 (EST) Message-ID: <528BE05E.8090501@akamai.com> Date: Tue, 19 Nov 2013 17:04:14 -0500 From: Jason Baron MIME-Version: 1.0 To: Ingo Molnar , "benh@kernel.crashing.org" , "paulus@samba.org" , Felipe Contreras Subject: Re: [PATCH v2] panic: Make panic_timeout configurable References: <20131118210436.233B5202A@prod-mail-relay06.akamai.com> <20131118143059.afe17d2faced16171a05eb10@linux-foundation.org> <528A9F24.1000206@akamai.com> <20131119070905.GF32367@gmail.com> In-Reply-To: <20131119070905.GF32367@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Cc: Andrew Morton , linuxppc-dev@lists.ozlabs.org, "linux-kernel@vger.kernel.org" , "ralf@linux-mips.org" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 11/19/2013 02:09 AM, Ingo Molnar wrote: > > * Jason Baron wrote: > >> On 11/18/2013 05:30 PM, Andrew Morton wrote: >>> On Mon, 18 Nov 2013 21:04:36 +0000 (GMT) Jason Baron wrote: >>> >>>> The panic_timeout value can be set via the command line option 'panic=x', or via >>>> /proc/sys/kernel/panic, however that is not sufficient when the panic occurs >>>> before we are able to set up these values. Thus, add a CONFIG_PANIC_TIMEOUT >>>> so that we can set the desired value from the .config. >>>> >>>> The default panic_timeout value continues to be 0 - wait forever, >>>> except for powerpc and mips, which have been defaulted to 180 and >>>> 5 respectively. This is in keeping with the fact that these >>>> arches already set panic_timeout in their arch init code. >>>> However, I found three exceptions- two in mips and one in powerpc >>>> where the settings didn't match these default values. In those >>>> cases, I left the arch code so it continues to override, in case >>>> the user has not changed from the default. It would nice if these >>>> arches had one default value, or if we could determine the >>>> correct setting at compile-time. >>> >>> Felipe is proposing a simpler patch ("panic: setup panic_timeout >>> early") which switches to early_param(). Is that sufficient for >>> the (undescribed!) failure which you are presumably observing? >>> >> >> No - that patch doesn't change the 'panic_timeout' value until the >> call to 'parse_early_param()' is made. If there is a panic before >> that point, the param doesn't do anything. The idea of this patch is >> to allow it to be configured at build-time. >> >> I've tested the patch by simply inserting a panic() call at the >> beginning of 'start_kernel()'. So, no I do not have a specific panic >> in mind for this. > > Would you be interested in picking up Felipe's patch/fix on top of > yours? I was unable to communicate with him efficiently, but I'd take > the patch if it's signed off by you. > > Thanks, > > Ingo > Sure, I can round up all the related patches in this area that make sense and re-submit as a series. Felipe, would the CONFIG_PANIC_TIMEOUT=xx .config parameter work for your needs, or would you still like to see the command-line processing moved up? I'd also like to hear from the PowerPC folks about the arch defaults there. Now, that mips is ok with CONFIG_PANIC_TIMEOUT, PowerPC is the only arch doing specific initialization of 'panic_timeout'. Thanks, -Jason