Return-path: Received: from mail-pw0-f46.google.com ([209.85.160.46]:42039 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754245Ab0FAUoG convert rfc822-to-8bit (ORCPT ); Tue, 1 Jun 2010 16:44:06 -0400 MIME-Version: 1.0 In-Reply-To: <201005311006.15282.br1@einfach.org> References: <20100528100901.14580.1322.stgit@fate.lan> <20100528212523.213125g8t0an4mn4@hayate.sektori.org> <1275078476.18152.10.camel@mj> <201005311006.15282.br1@einfach.org> From: "Luis R. Rodriguez" Date: Tue, 1 Jun 2010 13:43:46 -0700 Message-ID: Subject: Re: [ath5k-devel] [PATCH] ath5k: disable ASPM To: Bruno Randolf Cc: ath5k-devel@lists.ath5k.org, Pavel Roskin , Jussi Kivilinna , linux-wireless@vger.kernel.org, Stephen Hemminger , Alan Cox , bkuhn@softwarefreedom.org, linux-kernel@vger.kernel.org, BrianK.Lee@atheros.com Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: Note: this e-mail thread is on a public mailing list. Adding a few folks just for their information or in case they have anything to add and It is also good to remind ourselves about best practices for this stuff. On Sun, May 30, 2010 at 6:06 PM, Bruno Randolf wrote: > On Saturday 29 May 2010 05:27:56 Pavel Roskin wrote: >> If we need to add GPL code to ath5k, it could go to a separate file. >> But if that separation becomes inconvenient, we could drop BSD >> compatibility from ath5k.  I don't see any benefit from dual licensing, >> unless some existing ath5k contributors are BSD developers who would >> stop working on the code in case of relicensing, but I don't think it's >> the case. > > afaik, one of the reasons for the dual license is that *BSDs (our ancestors > from a ath5k point of view) should be able to benefit from improvements we > make. Some clarifications on this. Dual licensing GPL/BSD is typically done for the purpose of sharing code between GPL codebases and permissive licensed codebases but I should note that dual licensing GPL/BSD with this intention is legally equivalent to just licensing under the BSD license. Also the "Alternative" or "or" language used in dual licensing can sometimes be left up to interpretation and confusion and for this same reason SFLC's guidelines advise against this practice and instead recommend a simple clear permissive license [1]. In ath9k's case all files are permissive licensed on purpose, following SFLC's latest advice on this matter [1]. In ath5k only the hardware files were *only* permissive licensed since those were the files under review for sharing with OpenBSD. The other core driver files have the dual license just because of historical purposes but with the same intentions. I should note though that when sharing permissive licensed files on a larger GPL project it is also important to have in process a tag mechanism to annotate when contributions made to a permissive licensed file are indeed being kept under that same permissive licensed file. In Linux this is accomplished by the Signed-off-by tag, which has as a purpose stated under the 'Developer's Certificate of Origin 1.1': ------------------------------------------------------------------------------------------ By making a contribution to this project, I certify that: (a) The contribution was created in whole or in part by me and I have the right to submit it under the open source license indicated in the file; or ------------------------------------------------------------------------------------------ For ath5k initially we used to use a more implicit Changes-licensed-under tag but after a while this practice faded off in favor for educating more on the meaning behind the Singed-off-by tag, as stated above. There are more subsystems where this code sharing happens with permissive licensed code bases and sticking to the simple SOB makes it easier. > this applies mostly to atheros chipset related things, and is irrelevant > for linux-only implementation specifics. Actually the Linux kernel has other places where we care to share with the other BSD families, another example I am aware of is ACPI code. There may be others, but I am not too sure. > also we can mix BSD and GPL in one file - see debug.c No, once you have GPL a file the entire driver becomes GPL as a whole, the final binary that is. The ath5k/debug.c file is GPL, and future contributions would be made only as GPL then. If you want to separate permissive licensed changes from GPL changes that technically is possible but its just a pain in the ass and silly. For this reason I recommend to keep GPL files separate from permissive files. But yes, it is also possible to keep some GPL files and some permissive licensed files for a driver and ath5k is good example of such a case: * GPL files (debug.c) * Dual licensing for historical purposes (core driver) * Clean simple permissive license (ISC license, on hardware code) [1] http://www.softwarefreedom.org/resources/2007/gpl-non-gpl-collaboration.html Luis