From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 22 Nov 2013 12:54:17 +1100 From: Michael Ellerman To: Jason Baron Subject: Re: [PATCH v2] panic: Make panic_timeout configurable Message-ID: <20131122015416.GA23897@concordia> References: <20131118210436.233B5202A@prod-mail-relay06.akamai.com> <20131118143059.afe17d2faced16171a05eb10@linux-foundation.org> <528A9F24.1000206@akamai.com> <20131119070905.GF32367@gmail.com> <528BE05E.8090501@akamai.com> <20131121111638.GA15913@concordia> <528E795A.6070600@akamai.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <528E795A.6070600@akamai.com> Cc: Felipe Contreras , "linux-kernel@vger.kernel.org" , "ralf@linux-mips.org" , "paulus@samba.org" , Andrew Morton , "linuxppc-dev@lists.ozlabs.org" , Ingo Molnar List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, Nov 21, 2013 at 04:21:30PM -0500, Jason Baron wrote: > On 11/21/2013 06:16 AM, Michael Ellerman wrote: > > On Tue, Nov 19, 2013 at 05:04:14PM -0500, Jason Baron wrote: > >> 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. > > ... > >> > >> 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'. > > > > Hi Jason, > > > > I think we'd like to choose the value at runtime, as we do now. The > > powerpc arch supports a wide spread of different hardware, so it's nice > > to be able to customise the value based on the platform. Also we build a > > single kernel that boots on many platforms, and so we can't pick the > > value at compile time. > > Hi, > > Ok, So powerpc sets the timeout to '180' during setup_arch(), but then > overrides the value to '10' only for pSeries. Yep. > The patch proposed in this thread, sets the default built-in value for > powerpc to 180 and then continues to override in pSeries, if its > still 180 (IE the user hasn't requested another value). This allows > the panic_timeout value to have an effect before we reach the > arch_init() code. Are you ok with this? That is, are you ok with the > proposed powerpc bits? Yes that looks OK to me. It means we get a non-zero value during early boot, which is nice, the user can override the value if they wish, and otherwise the existing behaviour is unchanged. cheers