Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932127AbVLCSoJ (ORCPT ); Sat, 3 Dec 2005 13:44:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932130AbVLCSoJ (ORCPT ); Sat, 3 Dec 2005 13:44:09 -0500 Received: from mail.dvmed.net ([216.237.124.58]:57835 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S932127AbVLCSoI (ORCPT ); Sat, 3 Dec 2005 13:44:08 -0500 Message-ID: <4391E764.7050704@pobox.com> Date: Sat, 03 Dec 2005 13:43:48 -0500 From: Jeff Garzik User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc4 (X11/20050929) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Adrian Bunk CC: Arjan van de Ven , linux-kernel@vger.kernel.org, Andrew Morton , Greg KH , James Bottomley Subject: Golden rule: don't break userland (was Re: RFC: Starting a stable kernel series off the 2.6 kernel) References: <20051203135608.GJ31395@stusta.de> <1133620598.22170.14.camel@laptopd505.fenrus.org> <20051203152339.GK31395@stusta.de> In-Reply-To: <20051203152339.GK31395@stusta.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. X-Spam-Score: 0.1 (/) X-Spam-Report: Spam detection software, running on the system "srv2.dvmed.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Adrian Bunk wrote: > IOW, we should e.g. ensure that today's udev will still work flawlessly > with kernel 2.6.30 (sic)? > > This could work, but it should be officially announced that e.g. a > userspace running kernel 2.6.15 must work flawlessly with _any_ future > 2.6 kernel. [...] Content analysis details: (0.1 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.1 RCVD_IN_SORBS_DUL RBL: SORBS: sent directly from dynamic IP address [69.134.188.146 listed in dnsbl.sorbs.net] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1803 Lines: 44 Adrian Bunk wrote: > IOW, we should e.g. ensure that today's udev will still work flawlessly > with kernel 2.6.30 (sic)? > > This could work, but it should be officially announced that e.g. a > userspace running kernel 2.6.15 must work flawlessly with _any_ future > 2.6 kernel. Fix the real problem: publicly shame kernel hackers that change userland ABI/API without LOTS of notice, and hopefully an old-userland compatibility solution implemented. We change kernel APIs all the time. Having made that policy decision, we have the freedom to rapidly improve the kernel, and avoid being stuck with poor designs of the past. Userland isn't the same. IMO sysfs hackers have forgotten this. Anytime you change or remove sysfs attributes these days, you have the potential to break userland, which breaks one of the grand axioms of Linux. Everybody knows "the rules" when it comes to removing system calls, but forgets/ignores them when it comes to ioctls, sysfs attributes, and the like. Thus, I've often felt that heavy sysfs (and procfs) use made it too easy to break userland. Maybe we should change the sysfs API to include some sort of interface versioning, or otherwise make it more obvious to the programmer that they could be breaking userland compat. Offhand, once implemented and out in the field, I would say a userland interface should live at least 1-2 years after the "we are removing this interface" warning is given. Yes, 1-2 years. Maybe even that is too small. We still have old_mmap syscall around :) Jeff - 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/