minimum stack size was Re: #define delay(...)

[Joel Sherrill]

Sergei Organov wrote:
> 

> > This name is a relic from the very EARLIEST days of RTEMS.
> 
> "EARLIEST days of RTEMS" recalled me that I've had another suggestion for
> RTEMS. What if in addition to one lower stack size limit
> RTEMS_MINIMUM_STACK_SIZE we introduce another constant,
> let's say, RTEMS_ABSOLUTE_MINIMUM_STACK_SIZE that will be indeed close to
> absolute minimum for given architecture. All the test programs (as well as
> applications) then will continue to use the former constant, but RTEMS core
> will check input stack size by comparing it to the latter constant.
> 
> The problem with current approach is that the constant is actually too large
> (e.g., 8K on PowerPC) and as RTEMS core doesn't allow to create tasks with
> smaller stacks, light-weight tasks take too much memory for stack. Using my
> suggestion ABSOLUTE_MINIMUM will be somewhere around 1K for PowerPC thus
> saving 7K for every light-weight task. Or did situation change in this area
> since RTEMS-3.6?

Hasn't changed but it has irritated me and I have something in mind.

What about minimum stack size defaulting to the current
RTEMS_MINIMUM_STACK_SIZE
value and the user being able to specify their own default size as an
override.  What do you think of this?

I have also toyed with the idea of moving the fields in CPU table
that are shared by all ports to the regular configuration table.
 
> BR,
> Sergei Organov.

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