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SubjectRe: [RFC][PATCH V3] GCOV: profile by modules
Hi Greg:
DId you mean that the GCOV_PROFILE_PREREQS should add depends
on !GCOV_PROFILE_ALL ,then when GCOV_PROFILE_ALL is enabled,
the config GCOV_PROFILE_PREREQS will no longer works.

Greg KH <gregkh@linuxfoundation.org> 于2020年5月22日周五 下午4:37写道:
>
> On Fri, May 22, 2020 at 03:19:17PM +0800, gengcixi@gmail.com wrote:
> > 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 | 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
>
>
> I understand the goal here, but don't you need to have the main GCov
> option depend on your new Kconfig option here? You have it switched
> around here, so what keeps all code from being built with gcov support
> at the moment?
>
> thanks,
>
> greg k-h

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