From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH 0/3] clone64() and unshare64() system calls Date: Wed, 09 Apr 2008 18:10:57 -0700 Message-ID: <47FD6921.6090408@zytor.com> References: <20080409222611.GA28087@us.ibm.com> <47FD5899.2040206@zytor.com> <20080410010717.GA28477@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20080410010717.GA28477-r/Jw6+rmf7HQT0dZR+AlfA@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: sukadev-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org Cc: "David C. Hansen" , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, clg-NmTC/0ZBporQT0dZR+AlfA@public.gmane.org, Containers , Pavel Emelyanov List-Id: containers.vger.kernel.org sukadev-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org wrote: >> >> If you're going to make it a 64-bit pass it in as a 64-bit number, instead >> of breaking it into two numbers. > > Maybe I am missing your point. The glibc interface could take a 64bit > parameter, but don't we need to pass 32-bit values into the system call > on 32 bit systems ? Not as such, no. The ABI handles that. To make the ABI clean on some architectures, it's good to consider a 64-bit value only in positions where they map to an even:odd register pair once slotted in. > Yes, this was discussed before in the context of Pavel Emelyanov's patch > > http://lkml.org/lkml/2008/1/16/109 > > along with sys_indirect(). While there was no consensus, it looked like > adding a new system call was better than open ended interfaces. That's not really an open-ended interface, it's just an expandable bitmap. -hpa