work space size

Joel Sherrill joel.sherrill at
Mon Sep 8 20:45:50 UTC 2008

Ray... cc'ing for your reduced footprint ticker.

Bassem Fahmy wrote:
> hi,
> i'm currently doing a bsp for atmel SAM7 controllers. these controllers have a 64K RAM. i was able to get the hello.exe and ticker.exe to work. in the beginning the ticker.exe was running ok but after the end of the last message i usually see a message of error of freeing an empty pointer. i found that the work space size is 56K. so in the ticker example instead of using double the MINIMUM STACK SIZE for each stack, i just used the MINIMUM STACK SIZE, so now i can get it to work ok without the error messages. but the  work space size is down from 56K to 43K,  added to that the data and bss section, there is no enough memory for any heap. my questions are:
> is what i did by reducing the STACK size of each task right or wrong?
> How can i reduce the work space size?
Unfortunately, the tests do not push down on the memory requirements.

minimum.exe is the best/only test which tries to reduce memory requirements.

You would have to modify ticker and hello to mimic how minimum is configured
to lower workspace usage.  You can reduce the minimum stack size you 
want in
your application, reduce the number of priorities to 8 or 16 (saves ~3K 
disable newlib reentrancy if you have to (1K per task).  If you configure

I suppose for 4.10, we need to figure out what to do generally to the tests
to reduce their footprint.  In the early days, RTEMS_MINIMUM_STACK_SIZE
was only intended to be able to run the tests.  Maybe we need  a pass to
get rid of all the 2* minimum's. 

I have cc'ed Ray because I know he has a reduced footprint ticker he pushes
at on the Thumb.

Just because we have shrunk the OS, now we have to shrink some of the
basic tests.

> Hint: i compile the rtems with -disable-posix -disable-itron -disable-networking -disable-cxx
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Joel Sherrill, Ph.D.             Director of Research & Development
joel.sherrill at        On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
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