From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH, RFC] panic-note: Annotation from user space for panics Date: Tue, 17 Nov 2009 07:45:43 -0800 Message-ID: References: <20091112021322.GA6166@dvomlehn-lnx2.corp.sa.net> <4AFC4D31.2000101@gmail.com> <20091112215649.GA28349@dvomlehn-lnx2.corp.sa.net> <20091113091031.3f6d4bba@marrow.netinsight.se> <1258112748.21596.1227.camel@localhost> <4AFE6A14.4010507@gmail.com> <1258447997.27437.76.camel@localhost> <2ea1731b0911170445x13225c19w797388d2211de2d9@mail.gmail.com> <1258463404.27437.103.camel@localhost> Mime-Version: 1.0 Return-path: In-Reply-To: <1258463404.27437.103.camel@localhost> (Artem Bityutskiy's message of "Tue\, 17 Nov 2009 15\:10\:04 +0200") Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: dedekind1@gmail.com Cc: Marco Stornelli , Simon Kagstrom , David VomLehn , linux-embedded@vger.kernel.org, akpm@linux-foundation.org, dwm2@infradead.org, linux-kernel@vger.kernel.org, mpm@selenic.com, paul.gortmaker@windriver.com Artem Bityutskiy writes: > On Tue, 2009-11-17 at 13:45 +0100, Marco Stornelli wrote: >> 2009/11/17 Artem Bityutskiy : >> > Take a look at my mails where I describe different complications we have >> > in our system. We really want to have an OOPS/panic + our environment >> > stuff to go together, at once. This makes things so much simpler. >> > >> > Really, what is the problem providing this trivial panic-note >> > capability, where user-space can give the kernel a small buffer, and ask >> > the kernel to print this buffer at the oops/panic time. Very simple and >> > elegant, and just solves the problem. >> > >> > Why perversions with time-stamps, separate storages are needed? >> > >> > IOW, you suggest a complicated approach, and demand explaining why we do >> > not go for it. Simply because it is unnecessarily complex. >> >> I don't think it's a complicated approach we are talking of a system >> log like syslog with a temporal information, nothing more. > > We need to store this information of NAND flash. Implementing logs on > NAND flash is about handling bad blocks, choosing format of records, and > may be even handling wear-levelling. This is not that simple. > > And then I have match oops to the userspace environment prints, using I > guess timestamps, which is also about complications in userspace. > >> > This patch solves the problem gracefully, and I'd rather demand you to point what >> > is the technical problem with the patches. >> > >> >> Simply because I think that we should avoid to include in the kernel >> things we can do in a simply way at user space level. > > If it is much easier to have in the kernel, then this argument does not > work, IMHO. > >> I think this >> patch is well done but it's one of the patches that are solutions "for >> embedded only", but it's only my opinion. > > Also IMHO, but having embedded-only things is not bad at all. Why not use the kdump hook? If you handle a kernel panic that way you get enhanced reliability and full user space support. All in a hook that is already present and already works. Eric