Current status of mcf52235 port?

Joel Sherrill joel.sherrill at
Mon Aug 18 16:51:06 UTC 2008

Matthew should answer in detail about his application.
I will share some details on the minimum executable
which is the smallest baseline to build from.  As you
require more RTEMS features in your application,
the code and data space required will increase.

I can only state that AFAIK this BSP hasn't had a lot
of analysis to ensure the BSP itself isn't accidentally
introducing dependencies.  minimum.exe is:

   text    data     bss     dec     hex filename
48448    2416    4576   55440    d890

Which seems larger than necessary for .text but I can't
prove that.  The minimum workspace required for RTEMS is
3112 bytes. 

So with no analysis to trim space, 32K SRAM - 10104 bytes
shown in minimum to get you one task and idle up, that leaves
22664 bytes SRAM available and ~208K Flash left if the code
is in flash.

Quick analysis of symbol table shows the common BSP issue
related to size.  The debug print support code is in the same
file as the console driver.  Using printk debug IO (which is always there)
results in the entire (unneeded) console driver being in, which
in turn pulls in the termios code.

Bottom line.. with a few minutes of work, the minimum footprint
for executables dropped to:

   text    data     bss     dec     hex filename
  32464    2320    2656   37440    9240

That's 16K of a 48K executable GONE for a stupid BSP
structural issue that only required splitting a file to
fix.  This is the type of issue that has more impact on code
size than anything else.

So with MINOR analysis to trim space, we got back 2K
more SRAM and 16K Flash:

32K SRAM - 8088 bytes    ==> 24680 bytes SRAM free
256K Flash - 32464 bytes ==> 224.3K Flash free

And the symbol table still has more symbols than we saw in the
other minimum's I posted about today.  So there may be more
room specific to this BSP.


Devin Butterfield wrote:
> Hi,
> I am considering RTEMS for a project that will likely use the mcf52235 
> coldfire microcontroller. But before I dive in, I'm curious to know 
> how usable it is? With RTEMS loaded and executing from flash, is there 
> enough ram left over to host a practical application (8 - 10K)? Anyone 
> have success using this port in a real project?
> Thanks!
> --
> Regards, Devin

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
   Support Available             (256) 722-9985

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