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SubjectRe: [PATCH V7] GCOV: Add config to check the preqequisites situation
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On 16.09.2020 14:55, Cixi Geng wrote:
> Hi ALL:
> Not recieve more advise for a long time ,
> Can this submission be merged recently?

First off, sorry for not replying earlier.

I tried out your latest version of this patch and I don't see that my
previous comments have been addressed.

To re-iterate my point: I only see value in introducing a new
GCOV-related config symbol that is automatically selected, depending on
whether (as the name implies) all prerequisites for enabling GCOV-based
kernel profiling have been met. Such a symbol can take away the burden
of duplicating the prerequisite check as has been implemented for
GCOV_PROFILE_ALL.

I see no value in introducing a new config symbol that prompts the user
for a choice.

As it is, your patch introduces a new config symbol that prompts the
user for a choice:

$ make oldconfig
scripts/kconfig/conf --oldconfig Kconfig
*
* Restart config...
*
*
* GCOV-based kernel profiling
*
Enable gcov-based kernel profiling (GCOV_KERNEL) [Y/n/?] y
Profile entire Kernel (GCOV_PROFILE_ALL) [N/y/?] n
Profile Kernel for prereqs (GCOV_PROFILE_PREREQS) [Y/n/?] (NEW)

We do not need this prompt. Users specify that they want GCOV-profiling
by selecting GCOV_KERNEL. They specify that they want area-specific
profiling in symbols like your proposed SERIAL_GCOV. There is no need
for a user to manually confirm that the prerequisites for enabling
are-specific profiling are met.

I have detailed the required changes that would remove the prompt in my
previous reply. I'll add it here again for your convenience:

>>> +++ b/kernel/gcov/Kconfig
>>> @@ -51,6 +51,16 @@ 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 for prereqs"
>>> + default y if GCOV_KERNEL && !COMPILE_TEST
>>> + 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.
>>> +
>
> Replace the portion above with these lines:
>
> config GCOV_PROFILE_PREREQS
> def_bool y if GCOV_KERNEL && !COMPILE_TEST

And to clarify: by "the portion above" I was referring to all quoted
lines prefixed with a '+' sign.


>
> Cixi Geng <gengcixi@gmail.com> 于2020年8月20日周四 下午8:40写道:
>>
>> Hi All:
>>
>> Does this patch need more modification?
>>
>> <gengcixi@gmail.com> 于2020年7月27日周一 下午4:51写道:
>>>
>>> From: Cixi Geng <cixi.geng1@unisoc.com>
>>>
>>> Introduce new configuration option GCOV_PROFILE_PREREQS that can be
>>> used to check whether the prerequisites for enabling gcov profiling
>>> for specific files and directories are met.
>>>
>>> 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 | 12 ++++++++++++
>>> 3 files changed, 20 insertions(+)
>>>
>>> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
>>> index 780908d43557..55b128b6b31d 100644
>>> --- a/drivers/tty/serial/Kconfig
>>> +++ b/drivers/tty/serial/Kconfig
>>> @@ -1576,3 +1576,10 @@ 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 3110c77230c7..bb2e1fb85743 100644
>>> --- a/kernel/gcov/Kconfig
>>> +++ b/kernel/gcov/Kconfig
>>> @@ -51,4 +51,16 @@ 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 for prereqs"
>>> + depends on GCOV_KERNEL
>>> + depends on !COMPILE_TEST
>>> + def_bool y if GCOV_KERNEL && !COMPILE_TEST
>>> + 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.
>>> +
>>> endmenu
>>> --
>>> 2.17.1
>>>


--
Peter Oberparleiter
Linux on Z Development - IBM Germany

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