rtems coverage testing through an open source simulator?

[shizheng]

Ray wrote:
> You can use qemu to test pc586 bsp and score,  Skyeye is also a good choice for ARM platform (csb337 for example).
> --enable-tests in configure will help you generate test Makefile. The testsuites (tmtest sptest) cover all/most the API rtems offered
>   
as for this testsuit, I have checked and run it :)
I found $SRC_ROOT/testsuits/sptests/readme says:

This directory contains the RTEMS Single Processor Test Suite.
The tests in this directory provide near complete (98%+) test
coverage of the non-multiprocessor code in RTEMS.

I would like to know how 98%+ is obtained, and what's the 2%- left.
Is there any method to calculate this precisely?

regards, shizheng