From: Tri Vo <trong@android.com>
To: oberpar@linux.ibm.com
Cc: ghackmann@android.com, ndesaulniers@google.com,
linux-kernel@vger.kernel.org, kernel-team@android.com,
yamada.masahiro@socionext.com, akpm@linux-foundation.org,
Tri Vo <trong@android.com>
Subject: [PATCH v4 3/3] gcov: docs: add a note on GCC vs Clang differences
Date: Sun, 17 Mar 2019 19:54:11 -0700 [thread overview]
Message-ID: <20190318025411.98014-4-trong@android.com> (raw)
In-Reply-To: <20190318025411.98014-1-trong@android.com>
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").
Signed-off-by: Tri Vo <trong@android.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
---
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
---------------
--
2.21.0.225.g810b269d1ac-goog
prev parent reply other threads:[~2019-03-18 2:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-18 2:54 [PATCH v4 0/3] gcov: add Clang support Tri Vo
2019-03-18 2:54 ` [PATCH v4 1/3] gcov: Clang: move common GCC code into gcc_base.c Tri Vo
2019-03-18 2:54 ` [PATCH v4 2/3] gcov: Clang support Tri Vo
2019-03-18 2:54 ` Tri Vo [this message]
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