can i tailor the super core of RTEMS?

[Joel Sherrill]

Chris Johns wrote:
> 
> red-eye at 263.net wrote:
> >
> > i am reading the source code of RTEMS score(super code)!
> > can i tailor the super core of RTEMS?
> 
> I am not sure what you mean by "tailor". The parts work together and are
> configured by a range of configuration tables. Using these tables allows
> you a fine level of control.

At the API level.  There have been discussions about doing another
level of compile-time configuration similar to the Linux kernel
configuration process.  For example, you might configure the maximum
number of priority levels to be supported. In this case, this
would save some RAM usage per reduced priority level.

Similarly, you might configure and build without support for
priority inheritance, ceiling, POSIX signals, the Ada self 
support, or notepads. :)

Another thing I have experimented with is using the information
in confdefs.h to generate a custom version of the POSIX, Classic API,
and ITRON initialization routines.  If you don't configure
message queues, then there is no point in initializing that
manager and pulling in any code that "Message queue manager init"
references.

Doing any of these types of extended configuration is a
pure engineering effort.  If the community would like to
sponsor some of this effort, the footprint could be significantly
reduced in many configurations.

> > for example,when i did not use _Thread_Change_priority, i can del
> > it's code from my application?
> 
> Each function in the super core is in a separate file creating a
> separate .o. This means the linker should only pull in the parts you
> use. This depends on the API used, and the default libraries/modules you
> use.

Exactly.  

For the level of configuration you are talking about, the 
use of confdefs.h to tailor the init routines I mentioned above would
be the way to go.

> --
>  Chris Johns, cjohns @ cybertec.com.au

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
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