GCOV for skiboot

Unit tests

All unit tests are built+run with gcov enabled.

make coverage-report

will generate a unit test coverage report like: http://open-power.github.io/skiboot/coverage-report/


You can now build Skiboot itself with gcov support, boot it on a machine, do things, and then extract out gcda files to generate coverage reports from real hardware (or a simulator).

Building Skiboot with GCOV


You may need to make clean first.

This will build a skiboot lid roughly twice the size.

Flash/Install the skiboot.lid and boot.

Extracting GCOV data

The way we extract the gcov data from a system is by dumping the contents of skiboot memory and then parsing the data structures in user space with the extract-gcov utility in the skiboot repo.


mysim memory fwrite 0x30000000 0x240000 skiboot.dump


getmemproc 30000000 3407872 -fb skiboot.dump

linux (e.g. petitboot environment):

dd if=/proc/kcore skip=1572864 count=6656  of=skiboot.dump

You basically need to dump out the first 3MB of skiboot memory.

Then you need to find out where the gcov data structures are:

perl -e "printf '0x%x', 0x30000000 + 0x`grep gcov_info_list skiboot.map|cut -f 1 -d ' '`"

That address needs to be supplied to the extract-gcov utility:

./extract-gcov skiboot.dump 0x3023ec40

Once you’ve run extract-gcov, it will have extracted the gcda files from the skiboot memory image.

You can then run lcov:

lcov -b . -q -c -d . -o skiboot-boot.info

IMPORTANT you should point lcov to the gcov for the compiler you used to build skiboot, otherwise you’re likely to get errors.