From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45D1AC433E0 for ; Fri, 31 Jul 2020 21:37:59 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1A01A208E4 for ; Fri, 31 Jul 2020 21:37:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1A01A208E4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=joshtriplett.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=ksummit-discuss-bounces@lists.linuxfoundation.org Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id A3B532156F; Fri, 31 Jul 2020 21:37:57 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id tRuobxoIdp7d; Fri, 31 Jul 2020 21:37:54 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id B33452156B; Fri, 31 Jul 2020 21:37:54 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 86B8AC0050; Fri, 31 Jul 2020 21:37:54 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 9B4E3C004D for ; Fri, 31 Jul 2020 21:37:53 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 8B21086CC1 for ; Fri, 31 Jul 2020 21:37:53 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id dar48Yklrq4K for ; Fri, 31 Jul 2020 21:37:52 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from mslow2.mail.gandi.net (mslow2.mail.gandi.net [217.70.178.242]) by fraxinus.osuosl.org (Postfix) with ESMTPS id F0BC186190 for ; Fri, 31 Jul 2020 21:37:51 +0000 (UTC) Received: from relay5-d.mail.gandi.net (unknown [217.70.183.197]) by mslow2.mail.gandi.net (Postfix) with ESMTP id BDE4D3A4A36 for ; Fri, 31 Jul 2020 21:27:33 +0000 (UTC) X-Originating-IP: 50.39.163.217 Received: from localhost (50-39-163-217.bvtn.or.frontiernet.net [50.39.163.217]) (Authenticated sender: josh@joshtriplett.org) by relay5-d.mail.gandi.net (Postfix) with ESMTPSA id BAB531C0002; Fri, 31 Jul 2020 21:27:24 +0000 (UTC) Date: Fri, 31 Jul 2020 14:27:21 -0700 From: josh@joshtriplett.org To: Arnd Bergmann Message-ID: <20200731212721.GC32670@localhost> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Cc: linux-arch , Linux Kernel Mailing List , ksummit Subject: Re: [Ksummit-discuss] [TECH TOPIC] Planning code obsolescence X-BeenThere: ksummit-discuss@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ksummit-discuss-bounces@lists.linuxfoundation.org Sender: "Ksummit-discuss" On Fri, Jul 31, 2020 at 05:00:12PM +0200, Arnd Bergmann wrote: > The majority of the code in the kernel deals with hardware that was made > a long time ago, and we are regularly discussing which of those bits are > still needed. In some cases (e.g. 20+ year old RISC workstation support), > there are hobbyists that take care of maintainership despite there being > no commercial interest. In other cases (e.g. x.25 networking) it turned > out that there are very long-lived products that are actively supported > on new kernels. > > When I removed support for eight instruction set architectures in 2018, > those were the ones that no longer had any users of mainline kernels, > and removing them allowed later cleanup of cross-architecture code that > would have been much harder before. > > I propose adding a Documentation file that keeps track of any notable > kernel feature that could be classified as "obsolete", and listing > e.g. following properties: > > * Kconfig symbol controlling the feature > > * How long we expect to keep it as a minimum > > * Known use cases, or other reasons this needs to stay > > * Latest kernel in which it was known to have worked > > * Contact information for known users (mailing list, personal email) > > * Other features that may depend on this > > * Possible benefits of eventually removing it We had this once, in the form of feature-removal-schedule.txt. It was, itself, removed in commit 9c0ece069b32e8e122aea71aa47181c10eb85ba7. I *do* think there'd be value in having policies and processes for "how do we carefully remove a driver/architecture/etc we think nobody cares about". That's separate from having an actual in-kernel list of "things we think we can remove". _______________________________________________ Ksummit-discuss mailing list Ksummit-discuss@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/ksummit-discuss From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2E68C433DF for ; Fri, 31 Jul 2020 21:27:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C34B42087C for ; Fri, 31 Jul 2020 21:27:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729062AbgGaV1a (ORCPT ); Fri, 31 Jul 2020 17:27:30 -0400 Received: from relay5-d.mail.gandi.net ([217.70.183.197]:39629 "EHLO relay5-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727888AbgGaV1a (ORCPT ); Fri, 31 Jul 2020 17:27:30 -0400 X-Originating-IP: 50.39.163.217 Received: from localhost (50-39-163-217.bvtn.or.frontiernet.net [50.39.163.217]) (Authenticated sender: josh@joshtriplett.org) by relay5-d.mail.gandi.net (Postfix) with ESMTPSA id BAB531C0002; Fri, 31 Jul 2020 21:27:24 +0000 (UTC) Date: Fri, 31 Jul 2020 14:27:21 -0700 From: josh@joshtriplett.org To: Arnd Bergmann Cc: ksummit , Mike Rapoport , linux-arch , Linux Kernel Mailing List Subject: Re: [Ksummit-discuss] [TECH TOPIC] Planning code obsolescence Message-ID: <20200731212721.GC32670@localhost> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 31, 2020 at 05:00:12PM +0200, Arnd Bergmann wrote: > The majority of the code in the kernel deals with hardware that was made > a long time ago, and we are regularly discussing which of those bits are > still needed. In some cases (e.g. 20+ year old RISC workstation support), > there are hobbyists that take care of maintainership despite there being > no commercial interest. In other cases (e.g. x.25 networking) it turned > out that there are very long-lived products that are actively supported > on new kernels. > > When I removed support for eight instruction set architectures in 2018, > those were the ones that no longer had any users of mainline kernels, > and removing them allowed later cleanup of cross-architecture code that > would have been much harder before. > > I propose adding a Documentation file that keeps track of any notable > kernel feature that could be classified as "obsolete", and listing > e.g. following properties: > > * Kconfig symbol controlling the feature > > * How long we expect to keep it as a minimum > > * Known use cases, or other reasons this needs to stay > > * Latest kernel in which it was known to have worked > > * Contact information for known users (mailing list, personal email) > > * Other features that may depend on this > > * Possible benefits of eventually removing it We had this once, in the form of feature-removal-schedule.txt. It was, itself, removed in commit 9c0ece069b32e8e122aea71aa47181c10eb85ba7. I *do* think there'd be value in having policies and processes for "how do we carefully remove a driver/architecture/etc we think nobody cares about". That's separate from having an actual in-kernel list of "things we think we can remove".