KICS! brainstorming

[Daniel Gutson]

Thanks Joel,

  I will let you know once I address all your suggestions.

 Daniel.

On Wed, Jul 23, 2014 at 10:28 AM, Joel Sherrill
<joel.sherrill at oarcorp.com> wrote:
>
> On 7/22/2014 1:05 PM, Daniel Gutson wrote:
>> Hi,
>>
>>    we are working in a very RAM constrained board, and noticed that
>> some symbols could be moved to ROM by declaring them const.
>>
>> I have a slight idea about creating a consts-candidate detector tool
>> "KICS!" (Keep It Const, St.! :) ), and wanted to hear some other
>> people ideas.
>>
>> Initial thoughts:
>>   - one approach could be a gdb script, in which we first read all the
>> RAM memory of global objects after initialization (#1), and compare
>> the memory at the end (#2), see what remained unchanged; this could
>> throw many false positives but would be a starting point.
>>
>>   - another, I think tougher, is some pointer-tracking static analysis
>> as a gcc plugin (not sure if it is even possible).
>>
>> Other ideas?
> A couple other idea without knowing the BSP.
>
> Turn on per function/data items sections. This has been done for the
> SPARC BSPs
> and had a pretty big impact on the size of the tests. I haven't heard
> any reports
> on real applications yet. This will require changing gcc and linking
> flags and tinkering
> with the linker script if it doesn't use * in all the right places for
> pattern matching.
>
> Put together a minimal version of your app. Basically just make the
> calls you know
> you need. Don't worry if it runs. Look through the symbol table and see
> if there
> are unexpected or undesired capabilities.  For example, some BSPs
> unintentionally
> put the printk() support in the same file with the real console driver.
> Without
> per-function sections, something calls printk() and end up with the
> console driver
> and termios.
>
> If your application has lower requirements than what we think of as a
> minimum,
> we can refine our definition of minimum capabilities.
>
> All of these are important to us as a project. Knowing unexpected
> dependencies,
> turning on per item sections, and lowering minimum capabilities based on
> user
> feedbac.
>>
>>
>> (#1) after bsp_start? after rtems_initialize_data_structures?
>>
>> (#2) for some user-definition of "end", and/or after
>> rtems_shutdown_executive or alike?
>>
>> Thanks!
>>
>>    Daniel.
>>
>
> --
> Joel Sherrill, Ph.D.             Director of Research & Development
> joel.sherrill at OARcorp.com        On-Line Applications Research
> Ask me about RTEMS: a free RTOS  Huntsville AL 35805
> Support Available                (256) 722-9985
>



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Daniel F. Gutson
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