Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762233AbZJOAQ5 (ORCPT ); Wed, 14 Oct 2009 20:16:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762216AbZJOAQ5 (ORCPT ); Wed, 14 Oct 2009 20:16:57 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:38169 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762019AbZJOAQ4 (ORCPT ); Wed, 14 Oct 2009 20:16:56 -0400 Date: Wed, 14 Oct 2009 17:17:39 -0700 From: Sukadev Bhattiprolu To: "H. Peter Anvin" Cc: Roland McGrath , linux-kernel@vger.kernel.org, Oren Laadan , serue@us.ibm.com, "Eric W. Biederman" , Alexey Dobriyan , Pavel Emelyanov , Andrew Morton , torvalds@linux-foundation.org, mikew@google.com, mingo@elte.hu, Nathan Lynch , arnd@arndb.de, peterz@infradead.org, Louis.Rilling@kerlabs.com, kosaki.motohiro@jp.fujitsu.com, randy.dunlap@oracle.com, linux-api@vger.kernel.org, Containers , sukadev@us.ibm.com Subject: Re: [RFC][v8][PATCH 0/10] Implement clone3() system call Message-ID: <20091015001739.GC3515@us.ibm.com> References: <20091013044925.GA28181@us.ibm.com> <20091013205015.1ED524F7@magilla.sf.frob.com> <20091013232736.GA24392@us.ibm.com> <20091013235320.E90022746@magilla.sf.frob.com> <4AD525B3.2070906@zytor.com> <20091014223634.GB3515@us.ibm.com> <4AD6557D.3090501@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4AD6557D.3090501@zytor.com> X-Operating-System: Linux 2.0.32 on an i486 User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1961 Lines: 69 H. Peter Anvin [hpa@zytor.com] wrote: | On 10/14/2009 03:36 PM, Sukadev Bhattiprolu wrote: | > H. Peter Anvin [hpa@zytor.com] wrote: | > | | > | Overall it seems sane to: | > | | > | a) make it an actual 3-argument call; | > | b) make the existing flags a u32 forever, and make it a separate | > | argument; | > | c) any new expansion can be via the struct, which may want to have | > | an "c3_flags" field first in the structure. | > | > Ok, So will this work ? | > | > struct clone_args { | > u32 flags_high; /* new clone flags (higher bits) */ | > u32 reserved1; | > u32 nr_pids; | > u32 reserved2; | > u64 child_stack_base; | > u64 child_stack_size; | > u64 parent_tid_ptr; | > u64 child_tid_ptr; | > u64 reserved3; | > }; | > | > sys_clone3(u32 flags_low, struct clone_args *args, pid_t *pid_list) | > | > Even on 64bit architectures the applications have to use sys_clone3() for | > the extended features. | | Yes, although I'd just make flags_high a u64. so we allow 96 bits for flags ? | The other thing that might be worthwhile is to have a length field on | the structure; that way we could add new fields at the end if ever | necessary in the future. So: struct clone_args { u64 flags_high; /* new clone flags (higher bits) */ u64 reserved1; u32 nr_pids; u32 clone_args_size; u64 child_stack_base; u64 child_stack_size; u64 parent_tid_ptr; u64 child_tid_ptr; }; sys_clone3(u32 flags_low, struct clone_args *args, pid_t *pid_list) BTW, on 64-bit architectures, the flags_low would be 64-bits, but the high- bits there would be ignored right ? Not sure if we need a second reserved field now that we add ->clone_args_size. Thanks, Sukadev -- 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/