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Diffstat (limited to 'Documentation/dev-tools/gcov.rst')
| -rw-r--r-- | Documentation/dev-tools/gcov.rst | 43 |
1 files changed, 34 insertions, 9 deletions
diff --git a/Documentation/dev-tools/gcov.rst b/Documentation/dev-tools/gcov.rst index 69a7d90c320a..075df6a4598d 100644 --- a/Documentation/dev-tools/gcov.rst +++ b/Documentation/dev-tools/gcov.rst @@ -22,8 +22,8 @@ Possible uses: * minimizing kernel configurations (do I need this option if the associated code is never run?) -.. _gcov: http://gcc.gnu.org/onlinedocs/gcc/Gcov.html -.. _lcov: http://ltp.sourceforge.net/coverage/lcov.php +.. _gcov: https://gcc.gnu.org/onlinedocs/gcc/Gcov.html +.. _lcov: https://github.com/linux-test-project/lcov Preparation @@ -34,10 +34,6 @@ Configure the kernel with:: CONFIG_DEBUG_FS=y CONFIG_GCOV_KERNEL=y -select the gcc's gcov format, default is autodetect based on gcc version:: - - CONFIG_GCOV_FORMAT_AUTODETECT=y - and to get coverage data for the entire kernel:: CONFIG_GCOV_PROFILE_ALL=y @@ -79,6 +75,17 @@ Only files which are linked to the main kernel image or are compiled as kernel modules are supported by this mechanism. +Module specific configs +----------------------- + +Gcov kernel configs for specific modules are described below: + +CONFIG_GCOV_PROFILE_RDS: + Enables GCOV profiling on RDS for checking which functions or + lines are executed. This config is used by the rds selftest to + generate coverage reports. If left unset the report is omitted. + + Files ----- @@ -128,6 +135,8 @@ box for setups where kernels are built and run on the same machine. In cases where the kernel runs on a separate machine, special preparations must be made, depending on where the gcov tool is used: +.. _gcov-test: + a) gcov is run on the TEST machine The gcov tool version on the test machine must be compatible with the @@ -147,6 +156,8 @@ a) gcov is run on the TEST machine machine. If any of the path components is symbolic link, the actual directory needs to be used instead (due to make's CURDIR handling). +.. _gcov-build: + b) gcov is run on the BUILD machine The following files need to be copied after each test case from test @@ -169,6 +180,20 @@ b) gcov is run on the BUILD machine [user@build] gcov -o /tmp/coverage/tmp/out/init main.c +Note on compilers +----------------- + +GCC and LLVM gcov tools are not necessarily compatible. Use gcov_ to work with +GCC-generated .gcno and .gcda files, and use llvm-cov_ for Clang. + +.. _gcov: https://gcc.gnu.org/onlinedocs/gcc/Gcov.html +.. _llvm-cov: https://llvm.org/docs/CommandGuide/llvm-cov.html + +Build differences between GCC and Clang gcov are handled by Kconfig. It +automatically selects the appropriate gcov format depending on the detected +toolchain. + + Troubleshooting --------------- @@ -193,7 +218,7 @@ Cause may not correctly copy files from sysfs. Solution - Use ``cat``' to read ``.gcda`` files and ``cp -d`` to copy links. + Use ``cat`` to read ``.gcda`` files and ``cp -d`` to copy links. Alternatively use the mechanism shown in Appendix B. @@ -201,7 +226,7 @@ Appendix A: gather_on_build.sh ------------------------------ Sample script to gather coverage meta files on the build machine -(see 6a): +(see :ref:`Separated build and test machines a. <gcov-test>`): .. code-block:: sh @@ -234,7 +259,7 @@ Appendix B: gather_on_test.sh ----------------------------- Sample script to gather coverage data files on the test machine -(see 6b): +(see :ref:`Separated build and test machines b. <gcov-build>`): .. code-block:: sh |