The way the broadcast IP is currently fetched is by sending an ioctl()
request. The limitation of this is that the broadcast address may not
be set on the network interface (more specifically, it is usually not
set in docker containers). In those cases, it results in the broadcast
address becoming 0.0.0.0, which is not valid [1].
This fix uses the network IP and the netmask to compute the directed
broadcast address. This should be more reliable, as both of those are
always set on the network interface.
[1]: https://tools.ietf.org/html/rfc1122, section 3.2.1.3 (a)
The debug messages are too verbose to be run in a production vehicle and inherently were something that should only be run in SITL / debug sessions on hardware. Switching the flag to the PX4_DEBUG() macro does not only make this more explicit, but also saves a lot of flash space that otherwise was consumed by the strings.
The message handling was not obeying action focused messages and high-rate messages properly before. With this change update rates track the desired rates closely. Critical high-rate messages such as ADS-B are queued additionally to guarantee that all received packets are being correctly forwarded.
If we have not received an inbound heartbeat we are probably not connected and so user-facing output (which is even buffered) should go only out once we are connected.
This allows the ground control station or any other communication partner to query the supported versions. The key aspect is to send the response in MAVLink 2 framing to test the link with a MAVLink 2 framed message.
This patch fixes two issues:
* It sends the message on the first call, making sure that the first update gets sent out.
* It improves the rate scheduling. In an experiment with 0.5, 50 and 250 Hz all rates were correct within 0.3% of the intended rate.
This limits the maximum bandwidth of ulog streaming to 70% of the specified
mavlink datarate. If less is used, the leftover is assigned to the mavlink
streams, if more is used, it starts to drop.
mavlink status outputs the currently used rate, to check if a link is
saturated.
This moves the mavlink_log interface from ioctl to uORB and enables the
mavlink statusmessage output for Snapdragon. The API changes will lead
to changes in all modules that are using it.
Jonas Vautherin