From mboxrd@z Thu Jan 1 00:00:00 1970 From: Artem Bityutskiy Subject: Re: [PATCH, RFC] panic-note: Annotation from user space for panics Date: Wed, 18 Nov 2009 10:26:34 +0200 Message-ID: <1258532794.27437.124.camel@localhost> 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> Reply-To: dedekind1@gmail.com Mime-Version: 1.0 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="utf-8" To: "Eric W. Biederman" 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 On Tue, 2009-11-17 at 07:45 -0800, Eric W. Biederman wrote: > Artem Bityutskiy writes: >=20 > > 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 enviro= nment > >> > stuff to go together, at once. This makes things so much simpler= =2E > >> > > >> > 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 sim= ple 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 w= hy we do > >> > not go for it. Simply because it is unnecessarily complex. > >>=20 > >> I don't think it's a complicated approach we are talking of a syst= em > >> 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, usi= ng 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. > >> > > >>=20 > >> Simply because I think that we should avoid to include in the kern= el > >> 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. >=20 > 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 h= ook > that is already present and already works. =46or some reasons kdump does not work on ARM out of the box. We need t= o investigate this. --=20 Best Regards, Artem Bityutskiy (=D0=90=D1=80=D1=82=D1=91=D0=BC =D0=91=D0=B8=D1=82=D1=8E= =D1=86=D0=BA=D0=B8=D0=B9)