Index: uspace/lib/c/include/io/log.h
===================================================================
--- uspace/lib/c/include/io/log.h	(revision 5d94b16cbc3039fadf35402057e9f7dff1917037)
+++ uspace/lib/c/include/io/log.h	(revision 702536882b248833b02d3693809a7bb0f21bcbd1)
@@ -36,4 +36,5 @@
 
 #include <stdarg.h>
+#include <inttypes.h>
 #include <io/verify.h>
 
@@ -50,8 +51,18 @@
 } log_level_t;
 
-extern int log_init(const char *, log_level_t);
-extern void log_msg(log_level_t, const char *, ...)
-    PRINTF_ATTRIBUTE(2, 3);
-extern void log_msgv(log_level_t, const char *, va_list);
+typedef sysarg_t log_t;
+#define PRIlogctx PRIxn
+#define LOG_DEFAULT ((log_t) -1)
+#define LOG_NO_PARENT ((log_t) 0)
+
+extern const char *log_level_str(log_level_t);
+extern int log_level_from_str(const char *, log_level_t *);
+
+extern int log_init(const char *);
+extern log_t log_create(const char *, log_t);
+
+extern void log_msg(log_t, log_level_t, const char *, ...)
+    PRINTF_ATTRIBUTE(3, 4);
+extern void log_msgv(log_t, log_level_t, const char *, va_list);
 
 #endif
Index: uspace/lib/c/include/io/logctl.h
===================================================================
--- uspace/lib/c/include/io/logctl.h	(revision 702536882b248833b02d3693809a7bb0f21bcbd1)
+++ uspace/lib/c/include/io/logctl.h	(revision 702536882b248833b02d3693809a7bb0f21bcbd1)
@@ -0,0 +1,44 @@
+/*
+ * 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);
+extern int logctl_set_log_level(const char *, log_level_t);
+
+#endif
+
+/** @}
+ */
Index: uspace/lib/c/include/ipc/logger.h
===================================================================
--- uspace/lib/c/include/ipc/logger.h	(revision 702536882b248833b02d3693809a7bb0f21bcbd1)
+++ uspace/lib/c/include/ipc/logger.h	(revision 702536882b248833b02d3693809a7bb0f21bcbd1)
@@ -0,0 +1,81 @@
+/*
+ * 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
+ * @{
+ */
+
+#ifndef LIBC_IPC_LOGGER_H_
+#define LIBC_IPC_LOGGER_H_
+
+#include <ipc/common.h>
+
+typedef enum {
+	/** Set (global) default displayed logging level.
+	 *
+	 * Arguments: new log level.
+	 * Returns: error code
+	 */
+	LOGGER_CONTROL_SET_DEFAULT_LEVEL = IPC_FIRST_USER_METHOD,
+	/** Set displayed level for given log.
+	 *
+	 * Arguments: new log level.
+	 * Returns: error code
+	 * Followed by: string with full log name.
+	 */
+	LOGGER_CONTROL_SET_LOG_LEVEL
+} logger_control_request_t;
+
+typedef enum {
+	/** Create new log.
+	 *
+	 * Arguments: parent log id (0 for top-level log).
+	 * Returns: error code, log id
+	 * Followed by: string with log name.
+	 */
+	LOGGER_WRITER_CREATE_LOG = IPC_FIRST_USER_METHOD,
+	/** Write a message to a given log.
+	 *
+	 * Arguments: log id, message severity level (log_level_t)
+	 * Returns: error code
+	 * Followed by: string with the message.
+	 */
+	LOGGER_WRITER_MESSAGE
+} logger_writer_request_t;
+
+typedef enum {
+	/** Interface for controlling logger behavior. */
+	LOGGER_INTERFACE_CONTROL,
+	/** Interface for servers writing to the log. */
+	LOGGER_INTERFACE_WRITER
+} logger_interface_t;
+
+#endif
+
+/** @}
+ */
Index: uspace/lib/c/include/ipc/services.h
===================================================================
--- uspace/lib/c/include/ipc/services.h	(revision 5d94b16cbc3039fadf35402057e9f7dff1917037)
+++ uspace/lib/c/include/ipc/services.h	(revision 702536882b248833b02d3693809a7bb0f21bcbd1)
@@ -45,4 +45,5 @@
 	SERVICE_VFS        = FOURCC('v', 'f', 's', ' '),
 	SERVICE_LOC        = FOURCC('l', 'o', 'c', ' '),
+	SERVICE_LOGGER     = FOURCC('l', 'o', 'g', 'g'),
 	SERVICE_DEVMAN     = FOURCC('d', 'e', 'v', 'n'),
 	SERVICE_IRC        = FOURCC('i', 'r', 'c', ' '),
