Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932079AbWC3Hdd (ORCPT ); Thu, 30 Mar 2006 02:33:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751296AbWC3Hdd (ORCPT ); Thu, 30 Mar 2006 02:33:33 -0500 Received: from ns.virtualhost.dk ([195.184.98.160]:61196 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S1751185AbWC3Hdc (ORCPT ); Thu, 30 Mar 2006 02:33:32 -0500 Date: Thu, 30 Mar 2006 09:33:42 +0200 From: Jens Axboe To: Andrew Morton Cc: torvalds@osdl.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH][RFC] splice support Message-ID: <20060330073342.GK13476@suse.de> References: <20060329122841.GC8186@suse.de> <20060329143758.607c1ccc.akpm@osdl.org> <20060329180830.50666eff.akpm@osdl.org> <20060330072149.GI13476@suse.de> <20060329233037.14a24d4f.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060329233037.14a24d4f.akpm@osdl.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1588 Lines: 38 On Wed, Mar 29 2006, Andrew Morton wrote: > Jens Axboe wrote: > > > > > > Right now "flags" doesn't do anything at all, and you should just pass in > > > > zero. > > > > > > In that case perhaps we should be enforcing flags==0 so that future > > > flags-using applications will reliably fail on old flags-not-understanding > > > kernels. > > > > > > But that won't work if we later define a bit in flags to mean "behave like > > > old kernels used to". So perhaps we should require that bits 0-15 of > > > `flags' be zero and not care about bits 16-31. > > > > > > IOW: it might be best to make `flags' just go away, and add new syscalls in > > > the future as appropriate. > > > > Not if flags == 0 maintains the same behaviour. The only flag I can > > think of right now is the 'move' or 'gift' flag, meaning that the caller > > wants to migrate pages from the pipe instead of copying them. I'd > > imagine we'd get that in way before 2.6.17 anyways, so I think we're > > fine. > > OK.. Do you plan to make it reject unrecognised flags? Depends, not sure if eg a 'move' flag should be a hard or soft indication. Say we can't move a page and the caller asked us to migrate, we'd probably just do the sane thing and copy that one page. It would be silly to fail that request entirely. -- Jens Axboe - 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/