Re: Cygwin: Implement sched_[gs]etaffinity() commit breaks RTEMS port

[Sebastian Huber <sebastian dot huber at embedded-brains dot de>]

On 28/06/2019 10:48, Mark Geisert wrote:
> On Thu, 27 Jun 2019, Corinna Vinschen wrote:
> > On Jun 27 08:28, Sebastian Huber wrote:
> > > On 26/06/2019 15:12, Corinna Vinschen wrote:
> > > > On Jun 26 13:05, Sebastian Huber wrote:
> > > > > On 26/06/2019 11:37, Corinna Vinschen wrote:
> > > > > > On Jun 26 10:24, Sebastian Huber wrote:
> > > > > > > Hello,
> > > > > > >
> > > > > > > the following commit:
> > > > > > >
> > > > > > > commit 641ecb07533e85211b6abce334c85967f3f90209
> > > > > > > Author: Mark Geisert<mark@maxrnd.com>
> > > > > > > Date:   Sun Jun 23 14:51:06 2019 -0700
> > > > > > >
> > > > > > >       Cygwin: Implement sched_[gs]etaffinity()
> > > > > > > [...]
> > > > > > > breaks the RTEMS port:
> > > > > > > [...]
> > > > > > Looks like Cygwin has to define its own sys/cpuset.h included via
> > > > > > sys/_pthreadtypes.h.
> > > > >
> > > > > Yes, something like this. The RTEMS <sys/cpuset.h> is based on the 
> > > > > FreeBSD
> > > > > implementation and should be compatible to the Linux API. Maybe it 
> > > > > can move
> > > > > out of the RTEMS area into the global Newlib area.
> > > >
> > > > I'm not so sure, given the different names of macros and types used
> > > > inside cpu_set_t.  The new functions inside Cygwin rely on that.
> > >
> > > How do you implement this API in Cygwin:
> > >
> > > http://man7.org/linux/man-pages/man3/CPU_SET.3.html
> > >
> > > I think the RTEMS <sys/cpuset.h> implementation should cover it.
> >
> > AFAICS we don't.
> >
> > Mark, do you see much of a problem to rearrange your new
> > sched_[gs]etaffinity code to use the RTEMS sys/cpuset.h file?
> >
> > We can define our own sys/_cpuset.h, or use the RTEMS file as well.
>
> Hi folks,
> I was trying to minimize update scope while implementing the affinity 
> calls from Linux for Cygwin.  I noticed that taskset(1), from the 
> util-linux package, supplies its own CPU_SET implementation (copied from 
> glibc) so I decided to not supply one for Cygwin but let taskset use its 
> own.  I felt we could add CPU_SET to Cygwin when necessary, later.
>
> The macro #defines I added to sched.h are those needed by Linux CPU_SET 
> regardless of how it gets defined.  I worry about trying to use a 
> FreeBSD based CPU_SET -- just from unfamiliarity.

The RTEMS <sys/cpuset.h> implements the Linux and FreeBSD APIs. In case 
of conflict (and there are conflicts, the libc developers should talk 
more with each other) we choose the Linux variant.

> Corinna, I see how your workaround patch moves my macros to Cygwin's 
> sys/cpuset.h.  That seems fine to me.
>
> I don't see how the include linkage through _pthreadtypes.h works 
> though. How does a user app including <sched.h> get <sys/cpuset.h> 
> pulled in?

It is included via <sys/types.h> -> <sys/_pthreadtypes.h> -> <sys/cpuset.h>.

--
Sebastian Huber, embedded brains GmbH

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