Commit aa069a23 authored May 14, 2019 by Tri Vo Committed by Linus Torvalds May 14, 2019

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 6a61b70b ("gcov: remove
CONFIG_GCOV_FORMAT_AUTODETECT").

Link: http://lkml.kernel.org/r/20190318025411.98014-4-trong@android.com


Signed-off-by: Tri Vo <trong@android.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Cc: Daniel Mentz <danielmentz@google.com>
Cc: Greg Hackmann <ghackmann@android.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Petri Gynther <pgynther@google.com>
Cc: Prasad Sodagudi <psodagud@quicinc.com>
Cc: Trilok Soni <tsoni@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 826eba0d

Documentation/dev-tools/gcov.rst

+14 −4

Original line number	Diff line number	Diff line
		@@ -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
		---------------