From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763664AbcINU6T (ORCPT ); Wed, 14 Sep 2016 16:58:19 -0400 Received: from relay4-d.mail.gandi.net ([217.70.183.196]:37763 "EHLO relay4-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756946AbcINU6R (ORCPT ); Wed, 14 Sep 2016 16:58:17 -0400 Date: Wed, 14 Sep 2016 13:58:12 -0700 From: Josh Triplett To: Nicolas Pitre Cc: Thomas Gleixner , John Stultz , Richard Cochran , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2) posix-timers: make it configurable Message-ID: <20160914205812.GA11992@cloud> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 14, 2016 at 04:46:54PM -0400, Nicolas Pitre wrote: > Many embedded systems typically don't need them. This removes about > 22KB from the kernel binary size on ARM when configured out. > > Corresponding syscalls are routed to a stub logging the attempt to > use those syscalls which should be enough of a clue if they were > disabled without proper consideration. They are: timer_create, > timer_gettime: timer_getoverrun, timer_settime, timer_delete, > clock_adjtime. > > The clock_settime, clock_gettime, clock_getres and clock_nanosleep syscalls > are replaced by simple wrappers compatible with CLOCK_REALTIME, > CLOCK_MONOTONIC and CLOCK_BOOTTIME only. > > Signed-off-by: Nicolas Pitre > --- > > Changes from RFC/v1: > > - Stubbed-out functions moved to static inlines. > - The timer signal handling code is now removed. > - The list of removed syscalls is explicitly documented. > - The clock_settime, clock_gettime, clock_getres and clock_nanosleep > syscalls are minimally preserved as this required very little code. > > I'm now able to boot a copy of Fedora 21 with this patch and > CONFIG_POSIX_TIMERS=n with no apparent issues. This looks quite reasonable. Does booting a standard distro really require providing clock_settime? I'd still prefer to see the special-case sys_ni support dropped, especially since the most common syscalls now remain. However, if others want to see it kept, I won't object too strongly; whoever ends up implementing a common (and optional) version of that infrastructure for all syscalls can fold this into it. - Josh Triplett