From aa069a23a220e9ab00d6837b76917952d0fb587e Mon Sep 17 00:00:00 2001 From: Tri Vo Date: Tue, 14 May 2019 15:45:28 -0700 Subject: [PATCH] gcov: docs: add a note on GCC vs Clang differences Document some things of note to gcov users: 1. GCC gcov and Clang llvm-cov tools are not compatible. 2. The use of GCC vs Clang is transparent at build-time. Also adjust the documentation to account for the removal of config symbol CONFIG_GCOV_FORMAT_AUTODETECT by commit 6a61b70b43c9 ("gcov: remove CONFIG_GCOV_FORMAT_AUTODETECT"). Link: http://lkml.kernel.org/r/20190318025411.98014-4-trong@android.com Signed-off-by: Tri Vo Reviewed-by: Peter Oberparleiter Cc: Daniel Mentz Cc: Greg Hackmann Cc: Nick Desaulniers Cc: Petri Gynther Cc: Prasad Sodagudi Cc: Trilok Soni Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/dev-tools/gcov.rst | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/Documentation/dev-tools/gcov.rst b/Documentation/dev-tools/gcov.rst index 69a7d90c320a..46aae52a41d0 100644 --- a/Documentation/dev-tools/gcov.rst +++ b/Documentation/dev-tools/gcov.rst @@ -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 @@ -169,6 +165,20 @@ 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: http://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 ---------------