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logging: backend_uart: Reword buffer size Kconfig text

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As written, the title and description of the Kconfig option seem to
specify the logging sub-system will not flush until the buffer is full.
Someone reading this would expect that shorter log message will not be
flushed until the specified number of bytes accumulate.

This is not the case.  Each log message is flushed when finished.  The
size is only the maximum bytes of a single formatted message's contents
that will be accumated before the backend flushes.

What's more, it only applies in deferred mode.  In immediate mode there
is no buffering, not just of multiple log messages but also of the
message contents as they are formatted.

Signed-off-by: Trent Piepho <tpiepho@gmail.com>
This commit is contained in:
Trent Piepho 2022-12-19 18:52:05 -08:00 committed by Carles Cufí
parent ec0662734d
commit 2112844eea
1 changed files with 7 additions and 3 deletions
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10
subsys/logging/backends/Kconfig.uart
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@ -17,12 +17,16 @@ config LOG_BACKEND_UART_ASYNC
depends on !LOG_BACKEND_UART_OUTPUT_DICTIONARY_HEX
config LOG_BACKEND_UART_BUFFER_SIZE
int "Number of bytes to buffer in RAM before flushing"
int "Maximum number of bytes to buffer in RAM before flushing"
default 32 if LOG_BACKEND_UART_ASYNC
default 1
help
Sets the number of bytes which can be buffered in RAM before log_output_flush
is automatically called on the backend.
In deferred logging mode, sets the maximum number of bytes which can be buffered in
RAM before log_output_flush is automatically called on the UART backend. The buffer
will also be flushed after each log message.
In immediate logging mode, processed log messages are not buffered and are always
output one byte at a time.
config LOG_BACKEND_UART_AUTOSTART
bool "Automatically start UART backend"