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From:   gengcixi@gmail.com
To:     gregkh@linuxfoundation.org, jslaby@suse.com, oberpar@linux.ibm.com,
        linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     orsonzhai@gmail.com, zhang.lyra@gmail.com,
        Cixi Geng <cixi.geng1@unisoc.com>
Subject: [RFC PATCH v4] GCOV: profile by modules
Date:   Mon, 25 May 2020 18:00:54 +0800
Message-Id: <20200525100054.17700-1-gengcixi@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Cixi Geng <cixi.geng1@unisoc.com>

The CONFIG_GCOV_PROFILE_ALL will compile kernel by profiling entire
kernel which will lead to kernel run slower.Use GCOV_PROFILE_PREREQS
to control part of the kernel modules to open gcov.

Only add SERIAL_GCOV for an example.

Signed-off-by: Cixi Geng <cixi.geng1@unisoc.com>
---
 drivers/tty/serial/Kconfig  |  7 +++++++
 drivers/tty/serial/Makefile |  1 +
 kernel/gcov/Kconfig         | 14 ++++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index adf9e80e7dc9..6df002370f18 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1566,3 +1566,10 @@ endmenu
 
 config SERIAL_MCTRL_GPIO
 	tristate
+
+config SERIAL_GCOV
+	bool "Enable profile gcov for serial directory"
+	depends on GCOV_PROFILE_PREREQS
+	help
+	  The SERIAL_GCOV will add Gcov profiling flags when kernel compiles.
+	  Say 'Y' here if you want the gcov data for the serial directory,
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index d056ee6cca33..17272733db95 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -3,6 +3,7 @@
 # Makefile for the kernel serial device drivers.
 #
 
+GCOV_PROFILE := $(CONFIG_SERIAL_GCOV)
 obj-$(CONFIG_SERIAL_CORE) += serial_core.o
 
 obj-$(CONFIG_SERIAL_EARLYCON) += earlycon.o
diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig
index 3941a9c48f83..ea8b514f5676 100644
--- a/kernel/gcov/Kconfig
+++ b/kernel/gcov/Kconfig
@@ -51,6 +51,20 @@ config GCOV_PROFILE_ALL
 	larger and run slower. Also be sure to exclude files from profiling
 	which are not linked to the kernel image to prevent linker errors.
 
+config GCOV_PROFILE_PREREQS
+	bool "Profile Kernel subsytem"
+	depends on !COMPILE_TEST
+	depends on GCOV_KERNEL
+	depends on !GCOV_PROFILE_ALL
+	help
+	  This options activates profiling for the specified kernel modules.
+
+	  When some modules need Gcov data, enable this config, then configure
+	  with gcov on the corresponding modules,The directories or files of
+	  these modules will be added profiling flags after kernel compile.
+
+	  If unsure, say N.
+
 choice
 	prompt "Specify GCOV format"
 	depends on GCOV_KERNEL
-- 
2.17.1