Index: uspace/lib/c/Makefile
===================================================================
--- uspace/lib/c/Makefile	(revision cddcc4a3904768c1032861a518e712bd08ea3156)
+++ uspace/lib/c/Makefile	(revision 669f5caed8b5063907bbb28370a6c9ceccd1455e)
@@ -97,4 +97,5 @@
 	generic/io/printf.c \
 	generic/io/log.c \
+	generic/io/logctl.c \
 	generic/io/klog.c \
 	generic/io/snprintf.c \
Index: uspace/lib/c/generic/io/logctl.c
===================================================================
--- uspace/lib/c/generic/io/logctl.c	(revision 669f5caed8b5063907bbb28370a6c9ceccd1455e)
+++ uspace/lib/c/generic/io/logctl.c	(revision 669f5caed8b5063907bbb28370a6c9ceccd1455e)
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2012 Vojtech Horky
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libc
+ * @{
+ */
+
+#include <assert.h>
+#include <unistd.h>
+#include <errno.h>
+#include <io/logctl.h>
+#include <ipc/logger.h>
+#include <ns.h>
+
+/** IPC session with the logger service. */
+static async_sess_t *logger_session = NULL;
+
+static int connect_to_logger()
+{
+	if (logger_session != NULL)
+		return EOK;
+
+	logger_session = service_connect_blocking(EXCHANGE_SERIALIZE,
+	    SERVICE_LOGGER, LOGGER_INTERFACE_CONTROL, 0);
+	if (logger_session == NULL)
+		return ENOMEM;
+
+	return EOK;
+}
+
+
+int logctl_set_default_level(log_level_t new_level)
+{
+	int rc = connect_to_logger();
+	if (rc != EOK)
+		return rc;
+
+	async_exch_t *exchange = async_exchange_begin(logger_session);
+	if (exchange == NULL)
+		return ENOMEM;
+
+	rc = (int) async_req_1_0(exchange,
+	    LOGGER_CTL_SET_DEFAULT_LEVEL, new_level);
+
+	async_exchange_end(exchange);
+
+	return rc;
+}
+
+/** @}
+ */
Index: uspace/lib/c/include/io/logctl.h
===================================================================
--- uspace/lib/c/include/io/logctl.h	(revision 669f5caed8b5063907bbb28370a6c9ceccd1455e)
+++ uspace/lib/c/include/io/logctl.h	(revision 669f5caed8b5063907bbb28370a6c9ceccd1455e)
@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2011-2012 Vojtech Horky
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libc
+ * @{
+ */
+
+#ifndef LIBC_IO_LOGCTL_H_
+#define LIBC_IO_LOGCTL_H_
+
+#include <io/log.h>
+
+extern int logctl_set_default_level(log_level_t);
+
+#endif
+
+/** @}
+ */
Index: uspace/lib/c/include/ipc/logger.h
===================================================================
--- uspace/lib/c/include/ipc/logger.h	(revision cddcc4a3904768c1032861a518e712bd08ea3156)
+++ uspace/lib/c/include/ipc/logger.h	(revision 669f5caed8b5063907bbb28370a6c9ceccd1455e)
@@ -37,4 +37,9 @@
 
 typedef enum {
+	LOGGER_CTL_GET_DEFAULT_LEVEL = IPC_FIRST_USER_METHOD,
+	LOGGER_CTL_SET_DEFAULT_LEVEL
+} logger_control_request_t;
+
+typedef enum {
 	LOGGER_REGISTER = IPC_FIRST_USER_METHOD,
 	LOGGER_MESSAGE,
@@ -48,4 +53,6 @@
 
 typedef enum {
+	/** Interface for controlling logger behavior. */
+	LOGGER_INTERFACE_CONTROL,
 	/** Interface for servers writing to the log. */
 	LOGGER_INTERFACE_SINK,