Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751214AbWC3HVn (ORCPT ); Thu, 30 Mar 2006 02:21:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751212AbWC3HVm (ORCPT ); Thu, 30 Mar 2006 02:21:42 -0500 Received: from ns.virtualhost.dk ([195.184.98.160]:22788 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S1751216AbWC3HVl (ORCPT ); Thu, 30 Mar 2006 02:21:41 -0500 Date: Thu, 30 Mar 2006 09:21:49 +0200 From: Jens Axboe To: Andrew Morton Cc: Linus Torvalds , linux-kernel@vger.kernel.org Subject: Re: [PATCH][RFC] splice support Message-ID: <20060330072149.GI13476@suse.de> References: <20060329122841.GC8186@suse.de> <20060329143758.607c1ccc.akpm@osdl.org> <20060329180830.50666eff.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060329180830.50666eff.akpm@osdl.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1472 Lines: 38 On Wed, Mar 29 2006, Andrew Morton wrote: > > Besides, they should > > never be signed, if you do bitmasks and shifting on them: "int" is > > strictly worse than "unsigned" when we're talking flags. > > Sure, but is there any gain in making flags 64-bit on 64-bit machines when > we cannot use more than 32 bits in there anyway? unsigned int seems fine to me. > > 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. -- 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/