[RFC][PATCH V3] GCOV: profile by modules

From: gengcixi
Date: Fri May 22 2020 - 03:19:43 EST


From: Cixi Geng <cixi.geng1@xxxxxxxxxx>

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@xxxxxxxxxx>
---
drivers/tty/serial/Kconfig | 7 +++++++
drivers/tty/serial/Makefile | 1 +
kernel/gcov/Kconfig | 13 +++++++++++++
3 files changed, 21 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..4d75fa158726 100644
--- a/kernel/gcov/Kconfig
+++ b/kernel/gcov/Kconfig
@@ -51,6 +51,19 @@ 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
+ 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