settings: add support for static data #80360

Laczen · 2024-10-24T10:10:49Z

When settings is to be used in combination with a configuration system there is a need to create a interface between the compile time generated subsystem configuration and the settings subsystem. The PR proposes such a coupling by allowing compile time generated configuration to be added to a linker section of static data. This data can then be used
by the subsystems h_set() routine that is called by settings_load().

A typical use case for this solution would be a firmware that contains multiple configurations.

~~If the linker section would be placed in a separate (internal) flash page this could also be used for provisioning.~~
No this wouldn't work, it needs both the data and the linker section to reside on the separate flash page

ghost · 2024-10-24T17:12:42Z

subsys/settings/src/settings_static_data.c

+	ssize_t rc = (len > static_data->size) ? -EINVAL : len;
+
+	if (rc > 0) {
+		memcpy(data, static_data->data, len);


What if we had a "zero-copy" option of the read callback to further reduce the overall memory and CPU overhead of using the settings subsystem vs. using the macro target? This callback would only be made available by backends that actually have this capability so that the client (e.g. the configured subsystem) knows how to handle memory ownership on its side.

The static backend obviously has this capability...

The test is only showing the basic idea. The exchanged data could (in a configuration solution) be limited to pointers to the config data. The copy operation would then only be a copy of the pointers, not of the data.

tejlmand

minor nit, but nothing blocking.

tejlmand · 2024-10-25T13:54:32Z

subsys/settings/Kconfig

@@ -26,6 +26,11 @@ config SETTINGS_DYNAMIC_HANDLERS
 	help
 	  Enables the use of dynamic settings handlers

+config SETTINGS_STATIC_DATA
+	bool "settings static data"


minor nit: we have dynamic settings handlers right above:

zephyr/subsys/settings/Kconfig

Line 24 in 58b5970

bool "dynamic settings handlers"

should we perhaps change prompt to:

Suggested change

bool "settings static data"

bool "static settings data"

kartben

same comment as @tejlmand re: nit, and the typo in the README should be fixed as this is the kind of stuff that can cause confusion for people copy-pasting command to their CLI without thinking twice :)

kartben · 2024-11-29T13:45:28Z

tests/subsys/settings_static_data/README.rst

+This application can be built and executed on native_sim as follows:
+
+.. code-block:: console
+   $ ./scripts/twister -p native_sim -T tests/subsys/settings_commit_prio


typo in test path

kartben · 2024-11-29T13:48:06Z

subsys/settings/Kconfig

+config SETTINGS_STATIC_DATA
+	bool "settings static data"
+	help
+	  Enables the use of settings static data


Suggested change

Enables the use of settings static data

Enables the use of static settings data

When settings is to be used in combination with a configuration system there is a need to create a interface between the compile time generated subsystem configuration and the settings subsystem. The PR proposes such a coupling by allowing compile time generated configuration to be added to a linker section of static data. This data is then loaded when `settings_load()` is called. Signed-off-by: Laczen JMS <[email protected]>

Laczen · 2024-11-29T14:45:53Z

@kartben, I have updated the PR. I don't know if anyone is still interested in this since the configuration discussion died.

nordicjm

Can never remember how settings works with all the functions, is the idea that this allows changing of the value during runtime, and if so saving that changed value somewhere so it will be automatically loaded?

nordicjm · 2024-12-02T08:49:25Z

cmake/linker_script/common/common-rom.cmake

+  zephyr_iterable_section(NAME settings_static_data KVMA RAM_REGION GROUP RODATA_REGION SUBALIGN ${CONFIG_LINKER_ITERABLE_SUBALIGN})
+endif()
+
+


Suggested change

nordicjm · 2024-12-02T08:49:52Z

include/zephyr/settings/settings.h

+ * SETTINGS_STATIC_DATA_DEFINE().
+ */
+struct settings_static_data {
+


Suggested change

nordicjm · 2024-12-02T08:50:03Z

include/zephyr/settings/settings.h

+	const char *name;
+	/**< Name of data. */
+
+	const void *data;
+	/**< Pointer to data */
+
+	size_t size;
+	/**< Data size */


description goes above type

nordicjm · 2024-12-02T08:50:10Z

include/zephyr/settings/settings.h

+ * This creates a variable _sname prepended by settings_static_data_.
+ *
+ */
+


Suggested change

nordicjm · 2024-12-02T08:50:16Z

include/zephyr/settings/settings.h

+ * @param _size data size
+ *
+ * This creates a variable _sname prepended by settings_static_data_.
+ *


Suggested change

*

nordicjm · 2024-12-02T08:50:29Z

subsys/settings/Kconfig

@@ -26,6 +26,11 @@ config SETTINGS_DYNAMIC_HANDLERS
 	help
 	  Enables the use of dynamic settings handlers

+config SETTINGS_STATIC_DATA
+	bool "static settings data"


Suggested change

bool "static settings data"

bool "Static settings data"

nordicjm · 2024-12-02T08:50:50Z

subsys/settings/src/settings_static_data.c

+void settings_static_data_load(const struct settings_load_arg *arg)
+{
+	STRUCT_SECTION_FOREACH(settings_static_data, ch) {
+		if (settings_static_data_skip(ch, arg)) {


declare variables at top not part way through functions

nordicjm · 2024-12-02T08:51:01Z

tests/subsys/settings_static_data/src/main.c

+	LOG_INF("%s Called for %s", __func__, key);
+	zassert_true(settings_name_steq(key, "cfg", NULL), "bad settings key");
+
+	struct mysub_cfg cfg;


declare variables at top not part way through functions

nordicjm · 2024-12-02T08:51:24Z

tests/subsys/settings_static_data/README.rst

+.. _settings_static_data:
+
+Settings Subsystem static data Test
+#######################################


mismatched length

Laczen requested review from a user, nashif, henrikbrixandersen and jukkar October 24, 2024 10:10

zephyrbot added area: Settings Settings subsystem area: Build System area: Linker Scripts labels Oct 24, 2024

zephyrbot requested review from 57300, jeremybettis, nordicjm and tejlmand October 24, 2024 10:11

zephyrbot assigned tejlmand Oct 24, 2024

Laczen force-pushed the settings_static_data branch 2 times, most recently from 4f7c0cc to 58b5970 Compare October 24, 2024 11:46

ghost reviewed Oct 24, 2024

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tejlmand previously approved these changes Oct 25, 2024

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kartben requested changes Nov 29, 2024

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Laczen dismissed tejlmand’s stale review via ce837b7 November 29, 2024 14:44

Laczen force-pushed the settings_static_data branch from 58b5970 to ce837b7 Compare November 29, 2024 14:44

nordicjm reviewed Dec 2, 2024

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settings: add support for static data #80360

settings: add support for static data #80360

Laczen commented Oct 24, 2024 •

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	Enables the use of settings static data
	Enables the use of static settings data

		zephyr_iterable_section(NAME settings_static_data KVMA RAM_REGION GROUP RODATA_REGION SUBALIGN ${CONFIG_LINKER_ITERABLE_SUBALIGN})
		endif()

settings: add support for static data #80360

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Laczen commented Oct 24, 2024 • edited Loading

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Laczen commented Oct 24, 2024 •

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