From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:6f8:1178:4:290:27ff:fe1d:cc33]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TSmcp-0003m5-B1 for barebox@lists.infradead.org; Mon, 29 Oct 2012 10:31:20 +0000 Date: Mon, 29 Oct 2012 11:31:16 +0100 From: Sascha Hauer Message-ID: <20121029103116.GQ1641@pengutronix.de> References: <20121022160341.GF21588@game.jcrosoft.org> <1350922048-25699-1-git-send-email-plagnioj@jcrosoft.com> <20121029085055.GV24458@pengutronix.de> <20121029095604.GA31639@sig21.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20121029095604.GA31639@sig21.net> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: barebox-bounces@lists.infradead.org Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH 1/3] command: introduce abi version To: Johannes Stezenbach Cc: barebox@lists.infradead.org On Mon, Oct 29, 2012 at 10:56:04AM +0100, Johannes Stezenbach wrote: > On Mon, Oct 29, 2012 at 09:50:55AM +0100, Sascha Hauer wrote: > > On Mon, Oct 22, 2012 at 06:07:26PM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote: > > > This will allow to detect incompatibility between the env abi and the current > > > barebox one > ... > > > + > > > +#define COMMAND_ABI_VERSION 0 > > > > Please describe what this is. Something like: > > > > /* > > * This tracks incompatible changes to the barebox command interface. > > * This number is increased when changes are introduced which will cause > > * an older environment to no longer work. This could be: > > * > > * - changes in commandline options to commands > > * - renames of commands > > * - rename of device files > > * > > * If you change this value, add a explanation of the actual change to > > * Documentation/command-abi-changes.txt > > */ > > I wonder how this will work in practice. If I use a simple > /env/bin/init script and someone makes changes to a command > which isn't used by my /env/bin/init, will it still cause > my environment to be detected as incompatible? > > Maybe it would be a good idea to give the user control > over when to change COMMAND_ABI_VERSION by putting it into menuconfig? > > Either way I guess it means the default environment's init script > would need to implement automatic update to not lose important settings. I see the same problems and I am not really happy with introducing an ABI version. Also, introducing an ABI version could motivate people to break the ABI just because it's simple to do so and we have a standard way of doing it. > > Bottom line: It's much better to not make incompatible ABI changes _ever_. Agreed. In case of the change to the mount command this could mean to preserve the old ABI at least for compatibility. In case of my USB/MMC disk example this could mean to add links. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox