RTEMS with post-boot code.

[Joel Sherrill]

On Wed, 29 Oct 1997, Robin Kirkham wrote:

> On the whole, having used vxWorks for many years, I find the RTEMS way of
> bundling the application with whatever parts of an OS it requires into a
> single executable unit is in many ways cleaner and easier. Maybe it's not
> so good for repeated compile/test/debug cycles, but it is much better for
> managing systems in the field. (It is also the traditional embedded systems
> approach).

It is easier but forces you to relink the entire application and download
it.  GNU ld has some options to do something like "use address -- not
object code from this file".  I think using that, you could reuse the code
for RTEMS (and maybe other things like C library routines) which are
linked into  the monitor.

The key problem you will have to face is that RTEMS, the BSP, all device
drivers, etc will be in the ROM monitor and already initialized when your
application code is downloaded.  So it will have to be configured to
include your application requirements.  Plus you have to know what to
invoke in the downloaded image to do its application initialization.

I think some other RTEMS users have done similar things.  Hopefully
they can shed some light by telling us all what they have done.

--joel