From: Nicolas Pitre <nicolas.pitre@linaro.org>
To: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
John Stultz <john.stultz@linaro.org>,
Richard Cochran <richardcochran@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2) posix-timers: make it configurable
Date: Wed, 14 Sep 2016 17:09:53 -0400 (EDT) [thread overview]
Message-ID: <alpine.LFD.2.20.1609141659390.14769@knanqh.ubzr> (raw)
In-Reply-To: <20160914205812.GA11992@cloud>
On Wed, 14 Sep 2016, Josh Triplett wrote:
> 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 <nico@linaro.org>
> > ---
> >
> > 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 don't know. Maybe some date(1) implementation uses it. It is however
so small that there is no real advantage in explicitly removing it.
> 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.
Personally, I'd prefer to see more of those configurable syscalls before
introducing such infrastructure.
Nicolas
next prev parent reply other threads:[~2016-09-14 21:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-14 20:46 [PATCH v2) posix-timers: make it configurable Nicolas Pitre
2016-09-14 20:58 ` Josh Triplett
2016-09-14 21:09 ` Nicolas Pitre [this message]
2016-09-14 22:16 ` Josh Triplett
2016-09-14 22:34 ` kbuild test robot
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