Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757631AbZFYAdw (ORCPT ); Wed, 24 Jun 2009 20:33:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756619AbZFYAdj (ORCPT ); Wed, 24 Jun 2009 20:33:39 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:47151 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756799AbZFYAdh (ORCPT ); Wed, 24 Jun 2009 20:33:37 -0400 Date: Wed, 24 Jun 2009 17:33:16 -0700 From: Andrew Morton To: Davide Libenzi Cc: linux-kernel@vger.kernel.org, avi@redhat.com, kvm@vger.kernel.org, ghaskins@novell.com, rusty@rustcorp.com.au, bcrl@kvack.org Subject: Re: [patch] eventfd - revised interface and cleanups (2nd rev) Message-Id: <20090624173316.a129672d.akpm@linux-foundation.org> In-Reply-To: References: <20090623131239.711d9f83.akpm@linux-foundation.org> <20090623142511.c9068655.akpm@linux-foundation.org> <20090623144416.04c34268.akpm@linux-foundation.org> <20090623161852.660cab78.akpm@linux-foundation.org> <20090624161240.3efdbbfa.akpm@linux-foundation.org> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1907 Lines: 42 On Wed, 24 Jun 2009 16:52:06 -0700 (PDT) Davide Libenzi wrote: > > umm, yes please, I believe the patches should be split. And I'm still > > not seeing the justification for forcing CONFIG_EVENTFD onto all > > CONFIG_AIO users! > > Eventfd notifications became part of the AIO API (it's not even delivered > through a new syscall, from the AIO side - same existing aiocb struct and > io_submit syscall) once we merged it, That was a regression for existing embedded AIO users ;) > so IMHO (AIO && !EVENTFD) would be > similar to split AIO in AIO_READ and AIO_WRITE and have (AIO && !AIO_WRITE). > Considering that the kernel config, once you unleash the CONFIG_EMBEDDED > pandora box, allows you to select (AIO && !EVENTFD) w/out even a warning > about possible userspace breakages, this makes it rather a confusing > configuration if you ask me. Sure. But we do assume that one someone sets CONFIG_EMBEDDED, they know what they're doing. We prefer to give them maximum flexibility and foot-shooting ability. As long as the maintenance cost of doing so in each case is reasonable, of course. > It's not a biggie from the kernel side, just a few ugly errors wrappers > around functions. For me AIO (or whatever userspace visible kernel > subsystem) should select all the components that are part of the userspace > API, but my argument ends here. Sure, it's not a biggie either way. Doubtful if many tiny systems are using AIO anyway. Heck, lots of them are running 2.4.18... But from the general this-is-the-way-we-do-things POV, it's preferred that the two features be separable under CONFIG_EMBEDDED if poss. -- 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/