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From: Simon Wright <simon@pogner.demon.co.uk>
Subject: Re: Runtime Error with gnat 3.10p
Date: 1998/05/26
Message-ID: <x7vhg2cj35x.fsf@pogner.demon.co.uk>#1/1
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Date: 1998-05-26T00:00:00+00:00
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"David C. Hoos, Sr." <david.c.hoos.sr@ada95.com> writes:

> Andreas Jungmaier wrote in message ...
> >Hello all,
> >
> >does anyone have an idea what the following little message is
> >about :
> >Failed Runtime Assertion : GNULLI failure---Set_Priority
> >
> >Note that this showed up after executing a compiled Ada program
> >containing several tasks (instantiated task types)
> >This is on RedHat-Linux. Could this have to do with the thread
> >libs coming with gnat ?
> Yes, it does.
> One of the runtimes requires root privileges to do tasking while the
> other does not (I forget which is which).

Actually, the native threads requires root privileges to do *Annex D
tasking* (as noted by Markus Kuhn).

The relevant code in s-taprop.adb (3.11a1) is

   procedure Set_Priority (T : Task_ID; Prio : System.Any_Priority) is
      Result : Interfaces.C.int;
      Param  : aliased struct_sched_param;

   begin
      T.LL.Current_Priority := Interfaces.C.int (Prio);
      Param.sched_priority := Interfaces.C.int (Prio);

      Result := pthread_setschedparam (T.LL.Thread, SCHED_FIFO, Param'Access);
      pragma Assert (Result = 0
        or else Shutdown ("GNULLI failure---Set_Priority"));

   end Set_Priority;

You would have thought this would result in an error for non-root
users, cos (libpthread-0.71) pthread_setschedparam() calls
__sched_setscheduler(), which is a system call not defined in libc5,
but is in (linux/kernel/sched.c 2.0.33) which says

	if ((policy == SCHED_FIFO || policy == SCHED_RR) && !suser())
		return -EPERM;

but here it seems to work just fine. Hmm. Perhaps when I get round to
upgrading to glibc ...