logging: add template for log configuration

[nordic-krch]

Added Kconfig template file to be used when log configuration
in a module is added. Added example usage of kconfig template
in logger sample.

It is using new kconfig feature added in: #9797 (issue #9761)

Signed-off-by: Krzysztof Chruscinski [email protected]

[nordic-krch]

fyi @Olivier-ProGlove @jhedberg @jukkar see the example how log configuration can be established in each module:
https://github.com/zephyrproject-rtos/zephyr/blob/1d8b49eb592a13e966949d0603b9e36d4bf2ea12/samples/subsys/logging/logger/Kconfig#L13

[jukkar]

Could this be split to two commits? The first one would add the template, and the second one would add the sample that shows how to use it.

[nordic-krch]

@jukkar done.

[jukkar]

LGTM

[codecov-io]

Codecov Report

Merging #9933 into master will not change coverage.
The diff coverage is n/a.

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  Files         213      213           
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  Branches     5624     5624           
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  Hits        13696    13696           
  Misses      10135    10135           
  Partials     2251     2251

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[carlescufi]

Looks good, Will add @ulfalizer to review too.

[jukkar]

I have been porting this to networking logging code and was wondering if something like this would be possible (ping @ulfalizer) :

Kconfig:

module=FOOBAR
module-str=FOOBAR component
module-help=Enables FOOBAR debug messages.
source "Kconfig.log_level_template"

Kconfig.log_level_template:

choice
	prompt "Log level for $(module-str)"
	default $(module)_LOG_LEVEL_WRN
	help
	  $(module-help)

Current code outputs the help text just plain "$(module-help)" instead of expected help text.

[ulfalizer]

Would look less cramped with spaces around the =. Assignments work like in Make, so leading spaces are stripped automatically.

[ulfalizer]

@jukkar

Current code outputs the help text just plain "$(module-help)" instead of expected help text.

No macro expansion is done in help texts, so not currently possible. I wonder if it would break stuff in case help texts talk about Make variables, though that's unlikely in Zephyr.

Do you think making a reference to the prompt would be possible in the meantime, or making it generic ("enables some-feature for the subsystem" or the like)?

[nashif]

do we have documentation how this template can be used and will be used?

[nordic-krch]

good point. it is work updating the documentation.

[carlescufi]

This is great. Just a minor comment, should we settle on an extension for Kconfig templates? I would perhaps suggest “.ktemplate”

[nordic-krch]

@carlescufi would you propose renaming file to log_config.ktemplate ?

[carlescufi]

@nordic-krch

@carlescufi would you propose renaming file to log_config.ktemplate ?

Actually looking at what we do today:
Kconfig.defconfig.nrf51822_QFAC
I think the consistent naming scheme would be:
Kconfig.template.logging

[nordic-krch]

@carlescufi maybe Kconfig.template.log_config since in future we might want to add another template (all must be in separate files) so Kconfig.template.logging is to wide. Don't you think?

[carlescufi]

@nordic-krch

Sounds good to me.

[dbkinder]

doc change looks OK.