summary of configuration default changes

[Stephan Wilms]

Hi,

Some context stuff first ... bear with me, the answer is right below :-)

> [joel wrote:]
> > Significantly lowered the default memory requirements:
> >     - CONFIGURE_RTEMS_INIT_TASKS_TABLE was 10 now 0
> >     - CONFIGURE_POSIX_INIT_THREAD_TABLE was 10 now 0
> >     - CONFIGURE_ITRON_INIT_TASK_TABLE was 10 now 0
> >     - CONFIGURE_LIBIO_MAXIMUM_FILE_DESCRIPTORS was 20 now 3
[...]

[and gerke asked:]
> just a stupit question: where should I define these defaults? And at what
> time? When I compile my own program or when I build RTEMS?

Typically you will not define the defaults themselves. They're part of 
RTEMS and reside in "confdefs.h". You should be *aware* of the 
defaults, though, because if you need a higher/different value you will 
have to define that value yourself in your application and *BEFORE* you 
include "confdefs.h".

When you decide to use the "confdefs.h" mechanism for configuring an 
application you will include this file in one of your ".c" files. An 
often adopted custom is to do this in "init.c" (mainly because that's 
how the RTEMS samples do it). All specific definitions that your 
application requires must be made before that inclusion. The defaults 
are only used for those values that you do *not* define yourself.

This is a short piece of code from the "ticker" sample to demonstrate 
the general principle:
  #define CONFIGURE_TEST_NEEDS_CONSOLE_DRIVER
  #define CONFIGURE_TEST_NEEDS_CLOCK_DRIVER
  #define CONFIGURE_RTEMS_INIT_TASKS_TABLE
  #define CONFIGURE_EXTRA_TASK_STACKS (3 * RTEMS_MINIMUM_STACK_SIZE)
  #include <confdefs.h>

Greetings,

--
Stephan Wilms (stephan.wilms at cwa.de) 
CWA-GmbH, Aachen, Germany