Re: Should _POSIX_TIMERS be set to 200809L instead of 0?

[Richard Braun <rbraun@sceen.net>]

On Tue, Feb 18, 2014 at 11:55:07PM +0100, Svante Signell wrote:
> Quoting:
> > This is a completely illegal and non-sensical combination. POSIX requires 
> > timers if clock selection is supported, since clock selection instrinsically 
> > depends on timers. Furthermore POSIX.2008 requires timers and the monotonic 
> > clock in any case (they are *not* optional).
> > 
> > So as already implied, your system is broken. It is your operating system, not 
> > VLC, that needs fixing.
> 
> However from
> http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap02.html
> one reads (quote):
> * The following symbolic constants shall be defined by the implementation as follows:
>   o Symbolic constants defined with the value 200809L:
>         _POSIX_CLOCK_SELECTION
>         ...
>         _POSIX_TIMERS
>     ...
> 
> * The system may support one or more options (see Options) denoted by the following symbolic constants:
> _POSIX_MONOTONIC_CLOCK
> 
> Who is right?

I'd say you are. _POSIX_MONOTONIC_CLOCK is indeed optional and not
implied by _POSIX_CLOCK_SELECTION. It merely states that CLOCK_MONOTONIC
is supported. Whether it makes sense to be able to select a single clock
is another topic...

-- 
Richard Braun