From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756462Ab2AKH2V (ORCPT ); Wed, 11 Jan 2012 02:28:21 -0500 Received: from mga11.intel.com ([192.55.52.93]:64294 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752457Ab2AKH2R (ORCPT ); Wed, 11 Jan 2012 02:28:17 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="105853019" Message-ID: <4F0D3A0B.4090709@linux.intel.com> Date: Wed, 11 Jan 2012 15:28:11 +0800 From: Chen Gong User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:9.0) Gecko/20111222 Thunderbird/9.0.1 MIME-Version: 1.0 To: Seiji Aguchi CC: "Luck, Tony" , Don Zickus , "linux-kernel@vger.kernel.org" , Matthew Garrett , Vivek Goyal , "Chen, Gong" , "akpm@linux-foundation.org" , "Brown, Len" , "'ying.huang@intel.com'" <'ying.huang@intel.com'>, "'ak@linux.intel.com'" <'ak@linux.intel.com'>, "'hughd@chromium.org'" <'hughd@chromium.org'>, "'mingo@elte.hu'" <'mingo@elte.hu'>, "jmorris@namei.org" , "a.p.zijlstra@chello.nl" , "namhyung@gmail.com" , "dle-develop@lists.sourceforge.net" , Satoru Moriya Subject: Re: [RFC][PATCH v4 -next 1/4] Move kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop() References: <5C4C569E8A4B9B42A84A977CF070A35B2C5827AF7F@USINDEVS01.corp.hds.com> <5C4C569E8A4B9B42A84A977CF070A35B2C5827AF81@USINDEVS01.corp.hds.com> <3908561D78D1C84285E8C5FCA982C28FBB21@ORSMSX104.amr.corp.intel.com> <5C4C569E8A4B9B42A84A977CF070A35B2C5827B01D@USINDEVS01.corp.hds.com> <20120105210123.GI5650@redhat.com> <5C4C569E8A4B9B42A84A977CF070A35B2C5827BBD8@USINDEVS01.corp.hds.com> <4F0BAB33.2090201@linux.intel.com> <5C4C569E8A4B9B42A84A977CF070A35B2C583163B0@USINDEVS01.corp.hds.com> In-Reply-To: <5C4C569E8A4B9B42A84A977CF070A35B2C583163B0@USINDEVS01.corp.hds.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 于 2012/1/11 4:29, Seiji Aguchi 写道: > >> I agree with you. How about adding macros or something like WARN_ON(XX_ARCH) or >> Kconfig to limit its scope? > > Thank you for giving me your idea. > Your suggestions above will work for me because I'm a x86 user. > If Tony agrees to it, I can update my patch. > > But, I'm hesitating to add WARN_ON() or change Kconfig only for specific arch > because pstore aims for generic interface and this is related to its design. > Also, ramoops is going to use pstore now. It doesn't depend on x86. > I'm worried that ramoops users will complain about this change. > > So, I think a reasonable solution at this time is just adding some explanations > about smp_send_stop() to documentation as follows. > > Users can use pstore with their own responsibility and ask developers > if smp_send_stop() is reliable enough in panic situation on architecture they want to run. > > What do you think? > > --- > Documentation/ABI/testing/pstore | 8 ++++++++ > 1 files changed, 8 insertions(+), 0 deletions(-) > > diff --git a/Documentation/ABI/testing/pstore b/Documentation/ABI/testing/pstore > index ff1df4e..5583729 100644 > --- a/Documentation/ABI/testing/pstore > +++ b/Documentation/ABI/testing/pstore > @@ -11,6 +11,14 @@ Description: Generic interface to platform dependent persistent storage. > of the console log is captured, but other interesting > data can also be saved. > > + In case of panic, pstore is invoked after smp_send_stop() > + ,a function call stopping other cpus, so that we can get > + logs simpler and cleaner with just one running cpu. > + > + As for x86, smp_send_stop() is reliable enough to work in > + panic situation. But we are not guaranteed that it works > + reliably on other architectures. > + > # mount -t pstore -o kmsg_bytes=8000 - /dev/pstore > > $ ls -l /dev/pstore The explanation is great. but In my opinion, I still insist that a WARN_ON() is necessary. What do you think, Tony and Don?