From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sukadev Bhattiprolu Subject: Re: [RFC][v8][PATCH 0/10] Implement clone3() system call Date: Wed, 14 Oct 2009 17:17:39 -0700 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-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <4AD6557D.3090501-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "H. Peter Anvin" Cc: randy.dunlap-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, Containers , Nathan Lynch , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Louis.Rilling-aw0BnHfMbSpBDgjK7y7TUQ@public.gmane.org, "Eric W. Biederman" , kosaki.motohiro-+CUm20s59erQFUHtdCDX3A@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, mingo-X9Un+BFzKDI@public.gmane.org, torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, Alexey Dobriyan , Roland McGrath , Pavel Emelyanov List-Id: linux-api@vger.kernel.org H. Peter Anvin [hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org] wrote: | On 10/14/2009 03:36 PM, Sukadev Bhattiprolu wrote: | > H. Peter Anvin [hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org] 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