console: add simple dmesg functionality (enable only on v5)

src/platforms/px4_console_buffer.h

@@ -0,0 +1,60 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2019 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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
+ * COPYRIGHT OWNER OR CONTRIBUTORS 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file px4_console_buffer.h
+ * This implements a simple console buffer to store the full bootup output.
+ * It can be printed via the 'dmesg' utility.
+ * The output of stdout is redirected to CONSOLE_BUFFER_DEVICE, which is stored
+ * to a circular buffer and output to stderr, so that everything is still printed
+ * to the original console.
+ */
+
+#define CONSOLE_BUFFER_DEVICE "/dev/console_buf"
+
+__BEGIN_DECLS
+
+/**
+ * Initialize the console buffer: register the CONSOLE_BUFFER_DEVICE
+ * @return 0 on success, <0 error otherwise
+ */
+int px4_console_buffer_init();
+
+/**
+ * Print content of the console buffer to stdout
+ * @param follow if true keep waiting and print new content whenever the buffer
+ *               is updated
+ */
+void px4_console_buffer_print(bool follow);
+
+__END_DECLS