core/log: add optional log unit prefix

core/lib/include/log.h

@@ -19,6 +19,9 @@
  * This header offers a bunch of "LOG_*" functions that, with the default
  * implementation, just use printf, but honour a verbosity level.
  *
+ * If you want a logging unit name to be prefixed to the logs, define LOG_UNIT
+ * in the source file before including this header.
+ *
  * If desired, it is possible to implement a log module which then will be used
  * instead the default printf-based implementation.  In order to do so, the log
  * module has to
@@ -70,6 +73,17 @@ enum {
 #define LOG_LEVEL LOG_INFO
 #endif
 
+/**
+ * @brief Log with/without unit.
+ *
+ * @note Internal use only, use @ref LOG() instead.
+ */
+#ifdef LOG_UNIT
+#  define LOG_WRITE(level, fmt, ...) log_write((level), "%s: "fmt, LOG_UNIT, ##__VA_ARGS__)
+#else
+#  define LOG_WRITE(level, ...) log_write((level), __VA_ARGS__)
+#endif
+
 /**
  * @brief Log message if level <= LOG_LEVEL
  */
@@ -77,11 +91,11 @@ enum {
 #define LOG(level, ...) do { \
         _Pragma("clang diagnostic push") \
         _Pragma("clang diagnostic ignored \"-Wtautological-compare\"") \
-        if ((level) <= LOG_LEVEL) log_write((level), __VA_ARGS__); } while (0U) \
+        if ((level) <= LOG_LEVEL) LOG_WRITE((level), __VA_ARGS__); } while (0U) \
         _Pragma("clang diagnostic pop")
 #else
 #define LOG(level, ...) do { \
-        if ((level) <= LOG_LEVEL) log_write((level), __VA_ARGS__); } while (0U)
+        if ((level) <= LOG_LEVEL) LOG_WRITE((level), __VA_ARGS__); } while (0U)
 #endif /* __clang__ */
 
 /**

tests/sys/log_unit/Makefile

@@ -0,0 +1,6 @@
+include ../Makefile.sys_common
+
+# Enable debug log level
+CFLAGS += -DLOG_LEVEL=4
+
+include $(RIOTBASE)/Makefile.include

tests/sys/log_unit/log_with_unit.c

@@ -0,0 +1,20 @@
+/*
+ * SPDX-FileCopyrightText: 2025 ML!PA Consulting GmbH
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+/**
+ * @file
+ * @brief       Test logging with and log unit.
+ *
+ * @author      Mihai Renea <mihai.renea@ml-pa.com>
+ */
+
+#define LOG_UNIT "log_unit"
+#include "log.h"
+
+void log_with_unit(void)
+{
+    LOG_INFO("Hello!\n");
+    LOG_INFO("Hello %s!\n", "world");
+}

tests/sys/log_unit/log_without_unit.c

@@ -0,0 +1,18 @@
+/*
+ * SPDX-FileCopyrightText: 2025 ML!PA Consulting GmbH
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+/**
+ * @file
+ * @brief       Test logging with and without log unit.
+ *
+ * @author      Mihai Renea <mihai.renea@ml-pa.com>
+ */
+#include "log.h"
+
+void log_without_unit(void)
+{
+    LOG_INFO("Hello!\n");
+    LOG_INFO("Hello %s!\n", "world");
+}

tests/sys/log_unit/main.c

@@ -0,0 +1,22 @@
+/*
+ * SPDX-FileCopyrightText: 2025 ML!PA Consulting GmbH
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+/**
+ * @file
+ * @brief       Test logging with and without log unit.
+ *
+ * @author      Mihai Renea <mihai.renea@ml-pa.com>
+ */
+
+void log_with_unit(void);
+void log_without_unit(void);
+
+int main(void)
+{
+    log_with_unit();
+    log_without_unit();
+
+    return 0;
+}

tests/sys/log_unit/tests/01-run.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+
+import sys
+from testrunner import run
+
+
+def testfunc(child):
+    child.expect_exact("log_unit: Hello!")
+    child.expect_exact("log_unit: Hello world!")
+
+    # no unit name - match the beginning of the line
+    child.expect("\n")
+    child.expect("^Hello!")
+    child.expect("\n")
+    child.expect("^Hello world!")
+
+
+if __name__ == "__main__":
+    sys.exit(run(testfunc))