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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, Tri Vo <trong@android.com>
Subject: [PATCH v3 3/3] gcov: docs: add a note on GCC vs Clang differences
Date: Tue, 22 Jan 2019 15:37:49 -0800	[thread overview]
Message-ID: <20190122233749.42220-4-trong@android.com> (raw)
In-Reply-To: <20190122233749.42220-1-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.

Signed-off-by: Tri Vo <trong@android.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
 ---------------
 
-- 
2.20.1.321.g9e740568ce-goog


  parent reply	other threads:[~2019-01-22 23:39 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-22 23:37 [PATCH v3 0/3] gcov: add Clang support Tri Vo
2019-01-22 23:37 ` [PATCH v3 1/3] gcov: Clang: move common GCC code into gcc_base.c Tri Vo
2019-03-05 13:40   ` Peter Oberparleiter
2019-01-22 23:37 ` [PATCH v3 2/3] gcov: Clang support Tri Vo
2019-03-05 13:57   ` Peter Oberparleiter
2019-01-22 23:37 ` Tri Vo [this message]
2019-01-22 23:50   ` [PATCH v3 3/3] gcov: docs: add a note on GCC vs Clang differences Nick Desaulniers
2019-03-05 14:07   ` Peter Oberparleiter
2019-02-07  0:52 ` [PATCH v3 0/3] gcov: add Clang support Nick Desaulniers
2019-02-22  0:57   ` Nick Desaulniers
2019-03-05 14:29 ` Peter Oberparleiter
2019-03-12  4:57   ` Tri Vo

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