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 6a61b70 ("gcov: remove CONFIG_GCOV_FORMAT_AUTODETECT"). Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Tri Vo <[email protected]> Reviewed-by: Peter Oberparleiter <[email protected]> Cc: Daniel Mentz <[email protected]> Cc: Greg Hackmann <[email protected]> Cc: Nick Desaulniers <[email protected]> Cc: Petri Gynther <[email protected]> Cc: Prasad Sodagudi <[email protected]> Cc: Trilok Soni <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
chewitt · May 15, 2019 · aa069a2 · aa069a2
1 parent 826eba0
commit aa069a2
Showing 1 changed file with 14 additions and 4 deletions.
diff --git 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
 ---------------