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Date: Tue, 9 Nov 2010 11:26:41 +0100
From: Richard Cochran <richardcochran@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
        Alan Cox <alan@lxorguk.ukuu.org.uk>, Christoph Lameter <cl@linux.com>,
        John Stultz <johnstul@us.ibm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH RFC 2/8] clock device: convert clock_gettime
Message-ID: <20101109102641.GB2690@riccoc20.at.omicron.at>
References: <cover.1288897198.git.richard.cochran@omicron.at>
 <81ccd2674ebf26332898761ba6b7b54f395a15bd.1288897199.git.richard.cochran@omicron.at>
 <201011080756.50930.arnd@arndb.de>
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On Mon, Nov 08, 2010 at 07:56:50AM +0100, Arnd Bergmann wrote:
> On Thursday 04 November 2010, Richard Cochran wrote:
> >  #define CPUCLOCK_PERTHREAD_MASK	4
> >  #define CPUCLOCK_WHICH(clock)	((clock) & (clockid_t) CPUCLOCK_CLOCK_MASK)
> >  #define CPUCLOCK_CLOCK_MASK	3
> > @@ -28,12 +40,17 @@ struct cpu_timer_list {
> >  #define CPUCLOCK_VIRT		1
> >  #define CPUCLOCK_SCHED		2
> >  #define CPUCLOCK_MAX		3
> > +#define CLOCKFD			CPUCLOCK_MAX
> > +#define CLOCKFD_MASK		(CPUCLOCK_PERTHREAD_MASK|CPUCLOCK_CLOCK_MASK)
> 
> It looks like you are turning a kernel internal interface into a user ABI,
> which I think is highly questionable. Using the bits like this internally is
> ok, but making it part of the syscall ABI means that we can never change this
> in the future.

This set of defines is already part of the ABI and has been copied
into glibc.  I am extending the (mis)use of the clock id by adding one
more case.

Richard


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