Re: [PATCH RFC 2/8] clock device: convert clock_gettime

[Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>]

On Tuesday 09 November 2010, Richard Cochran wrote:
> 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.

Ok, that is very different then. I wonder why posix-timers.h is not an exported
header file, it might be good to change that to make it explicit which parts of
it define the ABI and which parts are kernel internal.

	Arnd