Return-path: Received: from mail-we0-f180.google.com ([74.125.82.180]:48416 "EHLO mail-we0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1162523Ab3DETQs (ORCPT ); Fri, 5 Apr 2013 15:16:48 -0400 MIME-Version: 1.0 In-Reply-To: <201304052008.15412.chunkeey@googlemail.com> References: <201304051903.11215.chunkeey@googlemail.com> <201304052008.15412.chunkeey@googlemail.com> Date: Fri, 5 Apr 2013 12:16:46 -0700 Message-ID: (sfid-20130405_211725_841237_341D76AC) Subject: Re: Version number policy! From: Adrian Chadd To: Christian Lamparter Cc: Eugene Krasnikov , "Luis R. Rodriguez" , linux-bluetooth , linux-wireless , ath9k_htc_fw , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: The point here is that once we hit a new major version, all the previous version checks can go away. So, if we decide to change some WMI message formats, it'll be in 2.x rather than 1.x. For example, has talked about killing off rate control in the NIC and doing it on the host. I'm happy with that (since it's easy enough to move back into the NIC if people want it for whatever reason) so: * Do we make it configurable? * Do we make it backwards compatible? * Do we just say "oh screw this" and treat it as part of the next major revision? If I were doing this for work and there was a long lifetime requirement for this stuff, then sure, we may have pressure from various groups to maintain backwards compatibility. And as we do so, we end up slowly bloating out the firmware and adding more driver capabilities. But since we're doing this in an open community, we can just create branches and let people who wish to maintain things do so, whilst not tying ourselves down too much. We have very specific pressures here (ie, how much RAM and CPU these little USB SoCs have), so we can't just infinitely grow the API. If there are bugfixes that someone like Google, Redhat or Canonical need for the 1.3 firmware in say, 2015 (when we've moved onto a much later evolution of this firmware) because they have a compat-wireless download that _only gets bugfixes_ and doesn't get new features (ie ,doesn't just sync against the latest compat-wireless to get bugfixes _and_ features), then they're quite welcome to cherry-pick fixes from mainline, merge them into the 1.3 branch and send a diff or pull request. But I personally don't want to maintain config options and backwards compatibility outside of what goes on in a minor branch. So, to address Christian's concern in more specific detail: * I intend that major revisions are break points, and that when we push out a new major revision, ath9k_htc (or whatever it becomes) will eventually update to use that; * .. then we can do things that break backwards compatibility, which means we can kill all those capability checks if we need to; * For things that occur during a given major release branch, we can either use a capability bitmap OR we can do it via versioning - because I don't want to see ath9k_htc try to support >1 major version; * How we do that check isn't really that big a deal - as long as the checks look like: if (feature_xxx(sc)) { } .. we can easily just change feature_xxx() to be a bitmap check or a version check. * And then once we push out a new major release, we can reap features that are either on by default in the new major release. How's that sound? Adrian