[PATCH 1/4] Minor conditionals to enable building Scheduler Simulator on GNU/Linux

[Gedare Bloom]

On Wed, May 28, 2014 at 2:49 PM, Joel Sherrill
<joel.sherrill at oarcorp.com> wrote:
>
> On 5/28/2014 10:22 AM, Gedare Bloom wrote:
>> On Wed, May 28, 2014 at 11:05 AM, Joel Sherrill
>> <joel.sherrill at oarcorp.com> wrote:
>>> On 5/28/2014 7:39 AM, Gedare Bloom wrote:
>>>> On Wed, May 28, 2014 at 5:00 AM, Sebastian Huber
>>>> <sebastian.huber at embedded-brains.de> wrote:
>>>>> On 2014-05-28 00:16, Joel Sherrill wrote:
>>>>>> - rtems/score/threadimpl.h: _Thread_Start_multitasking does return
>>>>>>    on Scheduler Simulator. Initializing RTEMS returns to the command
>>>>>>    interpreter.
>>>>>>
>>>>>> - rtems/score/smpimpl.h: _SMP_Start_multitasking_on_secondary_processor()
>>>>>>    is not applicable on the Scheduler Simulator and the no return
>>>>>> attribute
>>>>>>    gives a warning.
>>>>>>
>>>>>> - rtems/score/assert.h: Scheduler Simulator uses glibc assert.h on
>>>>>> GNU/Linux.
>>>>>>    This will likely need to be adjusted more for other host compilers and
>>>>>>    C libraries
>>>>>>
>>>>>> - threadrestart.c: Disable assert on Scheduler Simulator. Restarting self
>>>>>>    returns to the command interpreter.
>>>>> I would define RTEMS_COMPILER_NO_RETURN_ATTRIBUTE and _Assert() to nothing
>>>>> in case RTEMS_SCHEDSIM is defined.  Do you really need this debugging stuff
>>>>> for the scheduler simulator?  I don't think we should propagate oddities of
>>>>> the scheduler simulator throughout the code base.
>>>>>
>>>> Yes, this was my initial reaction as well. Probably at least you could
>>>> make Assert_Not_reached() a nop, or write a wrapper for assert that
>>>> depends on schedsim. Can schedsim work more like a real target for
>>>> this case of not returning? I guess usually the system ends up in a
>>>> fatal or halt state? Maybe you can interpose on that state to return
>>>> to the command interpreter.
>>> Schedsim does not really context switch so the paths that assume a task
>>> switches
>>> out and never returns are reachable paths. It is logically a single
>>> thread of control
>>> with the underlying RTEMS code thinking that a thread is "executing" on
>>> the various
>>> cores. When a thread blocks, control returns to the script with a new
>>> executing
>>> thread. In an SMP configuration, the scripts can also change CPU focus
>>> and execute
>>> commands in the context of  the executing thread on that core.
>>>
>>> I can live with disabling the noreturn checks and turning off that
>>> warning. I think
>>> that will eliminate the first two of the four spots touched above.
>>>
>>> But I don't want to disable the asserts. Right now, we can run with
>>> --enable-rtems-debug
>>> and not get any asserts. The consistency checks are really handy and
>>> they found
>>> bugs in the Affinity Scheduler. So I really do not want to disable
>>> them.  So killing
>>> assertions is undesirable.
>>>
>>> I could try to move all of the alternative assert logic under an
>>> RTEMS_SCHEDSIM.
>>> That would make it clearer what it is for and harder to trip.
>>>
>>> For know, making Assert_Not_reached() nothing on Schedsim would be
>>> acceptable
>>> for the _Thread_Restart() assertion.
>>>
>>> I think this would restrict the patch to the rtems assert.h. Is that
>>> acceptable?
>>>
>> Yes, that would be better.
> I can't turn off the no return warning via the command line. That
> touches basedefs.h.
>
> So basedefs.h and assert.h are the reduced set of files touched.
>
> New version attached.
You changed to using #if instead of #if defined. I think you want it
with the ifdef.

-Gedare