From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 24 May 2002 20:02:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 24 May 2002 20:02:15 -0400 Received: from vladimir.pegasys.ws ([64.220.160.58]:30469 "HELO vladimir.pegasys.ws") by vger.kernel.org with SMTP id ; Fri, 24 May 2002 20:02:14 -0400 Date: Fri, 24 May 2002 17:02:07 -0700 From: jw schultz To: Linus Torvalds Cc: Bill Davidsen , Dave McCracken , Linux Kernel Subject: Re: [RFC] POSIX personality Message-ID: <20020524170207.C9600@pegasys.ws> Mail-Followup-To: jw schultz , Linus Torvalds , Bill Davidsen , Dave McCracken , Linux Kernel In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.3.12i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 23, 2002 at 10:09:28AM -0700, Linus Torvalds wrote: > > > On Thu, 23 May 2002, Bill Davidsen wrote: > > > > I think the reason which comes to mind is avoiding future problems. By > > having a single POSIX mode flag not only does the program not have to know > > about setting the "right" other bits today, but if we find that POSIX > > behaviour is needed in some other area in the future, the program doesn't > > need to be modified and recompiled, because the POSIX behaviour "is in > > there" for all things. > > That's a nice argument in theory, but if you change the behaviour of > existing flags, you might fix some program for the real semantics, but you > might equally well _break_ some program that unwittingly depended on the > old semantics. > > So I think your argument is fundamentally flawed. The binary has been > tested with the old behaviour, and assuming that you can "fix" existing > binaries by changing kernel behaviour is a seriously flawed argument. > > Yes, it might work for some programs, but basically you're on very thin > ice. > > Does Linux break stuff when absolutely required? Sure. But designing an > interface that _plans_ on changing semantics is just incredibly stupid, > and should absolutely not be done. Ever. > > Linus It seems to me that the biggest issue here is maintaining POSIX behavior without having to modify application source every time the flag set changes. Perhaps a POSIX bitmask could be defined. For a degree of binary compatibility a few unused flags could be reserved and the POSIX bitmask include them whether they had meaning yet or not. -- ________________________________________________________________ J.W. Schultz Pegasystems Technologies email address: jw@pegasys.ws Remember Cernan and Schmitt