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Re: RTEMS questions



On Wed, 30 Oct 1996, Robert Friedlander wrote:

> I have some questions about my first RTEMS application.

Congrats on getting this far. :)

> My new board is now up and running. Its a 68332 with 256K fast SRAM. 
> RTEMS is working, I'm using a trivially modified version of John 
> S Gwynne's EFI332 port. I can run most of the samples, which is 
> reasuring, and have stand-alone programs to talk to some of my 
> peripherals.

If the changes are needed generically for the bsp, please submit them.

> 1) where do I start writing RTEMS device drivers? (!)
> I have an idea what I'd like them to do, but where do I register the 
> device numbers, and what are 'good' numbers to use? If anyone has any 
> sample code (for a dummy driver?) then that would be great, but 
> probably too much to expect.

The major device number is strictly a function of the order the device 
driver entries appear in the device driver configuration table.  For 
examples of simple drivers, you have the clock and console drivers in the 
bsp you are using.

There is a "stub driver" included which is used by at least one of the 
sptests.  It is in c/src/tests/support/stubdr.  The test using it should
be sp21.

> 2) what to I need to do to get C++ support going. I've turned on support in 
> the .cfg file, the cdtest compiles, but bombs out straight away when 
> the program runs. I can run c++ programs OK stand-alone.

The startup method is a little different in a C++ application.  The RTEMS 
initialization routine is invoked from a constructor.  Not every bsp is 
set up this way.  You should look at the relationship between bspstart.c 
and rtems-ctor.cc in the startup code for one of the following bsps:

hppa1_1/simhppa
sparc/sis
unix/posix

I suspect you are not getting the global constructors run.  The cdtest 
does not use global constructors.

> Thanks in advance for any advice, and to the RTEMS people at 
> Redstone, the EFI people, the FSF etc, etc (and anyone else who knows 
> me, as they say in phone-in chat shows over here). 

FYI we were formerly under contract to the U.S. Army to develop and 
support RTEMS.  They paid us to do both.  There are currently no Army 
funds for RTEMS support.  Commercial support is available via my firm in 
the tradition of other free software.

Also we are working with AdaCore to provide a gnat/rtems for embedded Ada 
developers. :)

--joel
Joel Sherrill                    Sr. Computer Scientist
joel@OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
   Support Available             (205) 722-9985
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