Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965156AbXBYWIs (ORCPT ); Sun, 25 Feb 2007 17:08:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965158AbXBYWIs (ORCPT ); Sun, 25 Feb 2007 17:08:48 -0500 Received: from ozlabs.org ([203.10.76.45]:50285 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965156AbXBYWIr (ORCPT ); Sun, 25 Feb 2007 17:08:47 -0500 Subject: Re: [PATCH 06/44 take 2] [UBI] startup code From: Rusty Russell To: Christoph Hellwig Cc: Artem Bityutskiy , Linux Kernel Mailing List , Frank Haverkamp , Thomas Gleixner , David Woodhouse , Josh Boyer In-Reply-To: <20070225055828.GC9137@infradead.org> References: <20070217165424.5845.4390.sendpatchset@localhost.localdomain> <20070217165454.5845.30875.sendpatchset@localhost.localdomain> <20070219105927.GB16930@infradead.org> <1171976456.4039.21.camel@sauron> <20070225055828.GC9137@infradead.org> Content-Type: text/plain Date: Mon, 26 Feb 2007 09:03:50 +1100 Message-Id: <1172441030.13541.21.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.8.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2417 Lines: 51 On Sun, 2007-02-25 at 05:58 +0000, Christoph Hellwig wrote: > On Tue, Feb 20, 2007 at 03:00:56PM +0200, Artem Bityutskiy wrote: > > > > +module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 000); > > > > +MODULE_PARM_DESC(mtd, "MTD devices to attach. Parameter format: " > > > > + "mtd=[,,]. " > > > > + "Multiple \"mtd\" parameters may be specified.\n" > > > > + "MTD devices may be specified by their number or name. " > > > > + "Optional \"vid_hdr_offs\" and \"data_offs\" parameters " > > > > + "specify UBI VID header position and data starting " > > > > + "position to be used by UBI.\n" > > > > + "Example: mtd=content,1984,2048 mtd=4 - attach MTD device" > > > > + "with name content using VID header offset 1984 and data " > > > > + "start 2048, and MTD device number 4 using default " > > > > + "offsets"); > > > > > > This is a very odd paramater interface. We really don't want drivers to use > > > module_param_call directly. You probably want various module_param_array calls > > > instead. > > > > Why not? We tried to avoid this but found out that this is the most > > decent interface. Specific advises are welcome. > > because this type of compount interface is really painful for the user. > the module.param=foo syntax makes sure paramaters can be used without > endless documentation for each and every single of them, and makes > sure module writers don't introduce bugs in their own parser reimplementations. > > Rusty, was it intentional that drivers can use __module_param_call? > Do you think the ubi use here is okay? The reason drivers can use __module_param_call is that they can implement their own "types" for module parameters, which will end up requiring this. Using it directly is only really for backwards compatibility (which is important!), but for new parameters, this multi-part self-parsing is nasty. Standard (but admittedly suboptimal) way to do this is having three parameters module_param_array(name, ...), module_param_array(header_offset, ...), module_param_array(data_start, ...). Hope that helps, Rusty. - 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/