Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S272460AbTG3Lhc (ORCPT ); Wed, 30 Jul 2003 07:37:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S272820AbTG3Lhc (ORCPT ); Wed, 30 Jul 2003 07:37:32 -0400 Received: from hermes.fachschaften.tu-muenchen.de ([129.187.202.12]:10447 "HELO hermes.fachschaften.tu-muenchen.de") by vger.kernel.org with SMTP id S272460AbTG3Lh3 (ORCPT ); Wed, 30 Jul 2003 07:37:29 -0400 Date: Wed, 30 Jul 2003 13:37:24 +0200 From: Adrian Bunk To: John Bradford Cc: Linux-Kernel@vger.kernel.org, Riley@Williams.Name Subject: Re: [2.6 patch] let broken drivers depend on BROKEN{,ON_SMP} Message-ID: <20030730113724.GA19356@fs.tum.de> References: <200307301129.h6UBTtBD001245@81-2-122-30.bradfords.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200307301129.h6UBTtBD001245@81-2-122-30.bradfords.org.uk> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3940 Lines: 101 On Wed, Jul 30, 2003 at 12:29:55PM +0100, John Bradford wrote: > > > > * Driver does not work, and is thus disabled. If it is not > > > > fixed in the near future, it will be considered to be > > > > OBSOLETE as well. > > > > > > > > CONFIG_BROKEN > > > > > > Please do _NOT_ do this - there is a far more important and worthwhile > > > reason to have a CONFIG_BROKEN than to simply save the few minutes of > > > inconvenience that including a non-compiling option in a kernel build > > > causes. > > > > > > Imagine the situation where a driver such as a SCSI driver builds > > > successfully, but it silently corrupts data under certain, (possibly > > > rare), circumstances. > > > > > > In that case, it's important to warn people that it's broken, because > > > it's not necessarily obvious, and could case significant data loss. > > > If something doesn't compile, it already gives you an error message. > > > The only problem is a few minutes of wasted time. > > > > You forget one important thing: > > If a _user_ of a stable kernel notices "it doesn't even compile" this > > gives a very bad impression of the quality of the Linux kernel. > > I don't agree. The stock kernel is a work in progress, and things get > broken from time to time as a normal part of development. Experienced > users will realise that, and I wouldn't encourage inexperienced users > to compile their own kernel from the stock trees anyway, because they > could easily miss bugfixes, including data corruption and security > ones, simply because they assume that they are in the mainline > kernel. Whether you like it or not: Many non-kernel-hackers compile their own kernels. Even if you wouldn't encourage them, there are enough situations where they can't choose: It occurs often that a fix or support for some hardware is only in the latest -pre or in the -ac tree. You say "things get broken from time to time as a normal part of development". Ideally this should never happen in a stable series. We don't live in an ideal world, but we should try to be as close as possible to this goal. > Compiling your own kernel from the stock kernel trees is still > something that should be considered for experienced users only. > > Besides, what's worse? Possible data corruption or a bad impression? Possible data corruption is worse, but completely disabling this driver is even better. > > > > * Driver works on uniprocessor but not on SMP and is thus > > > > disabled when compiling for SMP. It is assumed that the > > > > driver will be fixed for SMP if relevant. > > > > > > > > CONFIG_BROKEN_ON_SMP > > > > > > Please _don't_ do this either. It implies that if > > > CONFIG_BROKEN_ON_SMP isn't set, then it's SMP safe - a lot of drivers > > > will NOT have been tested on SMP, so it's a bad thing to assume that > > > is the case. > > >... > > > > My patch adds BROKEN_ON_SMP only to drivers that don't compile, but if a > > driver causes e.g. data corruption on SMP I don't see a reason against > > letting it depend on BROKEN_ON_SMP. > > The name BROKEN_ON_SMP implies that if you don't set it, what's left > is known to work on SMP. In a lot of cases, it'll actually be > untested on SMP. Say which other drivers are completely broken on SMP without a fix available or in the near future and it's easy to add a BROKEN_ON_SMP. As long as noone reports such a bug I assume a driver works. > John. cu Adrian -- "Is there not promise of rain?" Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. "Only a promise," Lao Er said. Pearl S. Buck - Dragon Seed - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/