doc: reference: logging: Extend frontend section
Update section about frontend feature.
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
diff --git a/doc/reference/logging/index.rst b/doc/reference/logging/index.rst
index a1ac8c5..2498fe7 100644
--- a/doc/reference/logging/index.rst
+++ b/doc/reference/logging/index.rst
@@ -11,7 +11,6 @@
developers. Messages are passed through a frontend and are then
processed by active backends.
Custom frontend and backends can be used if needed.
-Default configuration uses built-in frontend and UART backend.
Summary of the logging features:
@@ -19,7 +18,7 @@
consuming operations to a known context instead of processing and sending
the log message when called.
- Multiple backends supported (up to 9 backends).
-- Custom frontend supported.
+- Custom frontend support. When enabled no backends can be active.
- Compile time filtering on module level.
- Run time filtering independent for each backend.
- Additional run time filtering on module instance level.
@@ -48,6 +47,7 @@
- Slightly degrade performance in normal circumstances due to the fact that
allocation from ring buffer is more complex than from memslab.
- No change in logging API
+- Logging to frontend can be used together with backends.
- Logging backend API exteded with function for processing v2 messages.
.. note::
@@ -179,7 +179,9 @@
:kconfig:option:`CONFIG_LOG_DOMAIN_ID`: Domain ID. Valid in multi-domain systems.
-:kconfig:option:`CONFIG_LOG_FRONTEND`: Redirect logs to a custom frontend.
+:kconfig:option`CONFIG_LOG_FRONTEND`: Direct logs to a custom frontend.
+
+:kconfig:option`CONFIG_LOG_FRONTEND_ONLY`: No backends are used when messages goes to frontend.
:kconfig:option:`CONFIG_LOG_TIMESTAMP_64BIT`: 64 bit timestamp.
@@ -518,11 +520,11 @@
Custom Frontend
===============
-Custom frontend is enabled using :kconfig:option:`CONFIG_LOG_FRONTEND`. Logs are redirected
+Custom frontend is enabled using :kconfig:option:`CONFIG_LOG_FRONTEND`. Logs are directed
to functions declared in :zephyr_file:`include/logging/log_frontend.h`.
-This may be required in very time-sensitive cases, but most of the logging
-features cannot be used then, which includes default frontend, core and all
-backends features.
+If option :kconfig:option:`CONFIG_LOG_FRONTEND_ONLY` is enabled then log message is not
+created and no backend is handled. Otherwise, custom frontend can coexist with
+backends (not available in v1).
.. _logging_strings:
