Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 6 Dec 2002 17:24:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 6 Dec 2002 17:24:57 -0500 Received: from pizda.ninka.net ([216.101.162.242]:62952 "EHLO pizda.ninka.net") by vger.kernel.org with ESMTP id ; Fri, 6 Dec 2002 17:24:56 -0500 Date: Fri, 06 Dec 2002 14:29:27 -0800 (PST) Message-Id: <20021206.142927.88817589.davem@redhat.com> To: James.Bottomley@steeleye.com Cc: adam@yggdrasil.com, willy@debian.org, linux-kernel@vger.kernel.org Subject: Re: [RFC] generic device DMA implementation From: "David S. Miller" In-Reply-To: <200212062226.gB6MQsr04565@localhost.localdomain> References: <200212062226.gB6MQsr04565@localhost.localdomain> X-FalunGong: Information control. X-Mailer: Mew version 2.1 on Emacs 21.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1860 Lines: 43 From: James Bottomley Date: Fri, 06 Dec 2002 16:26:54 -0600 adam@yggdrasil.com said: > This makes me lean infinitesmally more toward a parameter to > dma_alloc rather than a separate dma_alloc_not_necessarily_consistent > function, because if there ever are other dma_alloc variations that we > want to support, it is more likely that there may be overlap between > the users of those features and then the number of different function > calls would have to grow exponentially (or we might then talk about > changing the API again, which is not the end of the world, but is > certainly more difficult than not having to do so). I think I like this. I don't. If the concept isn't all that important, why bother? See, if you have to allocate a whole new routine, you'll think about whether it makes sense or not. It's like adding a new system call, and the same arguments apply. I don't want a 'flags' thing, because that tends to be the action which opens the flood gates for putting random feature-of-the-day new bits. If you have to actually get a real API change made, it will get review and won't "sneak on in". I also don't want architectures adding arch specific flag bits that some drivers end up using, for example. The suggested scheme allows that, and I can guarentee you that people will do things like that. You must take the time to get the semantics right and make sure they really do handle the cases that are problematic. Random flag bits passed to a "do everything" dma_alloc function don't encourage that at all. - 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/