RFC: Add basic support for local and remote CAN #1719
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The CAN devices are matched in the network interfaces. The CAN device is not a typical network interface, so filter it. A new resource, CANPort, will be introduced to cover the CAN devices. Signed-off-by: Tomas Novotny <[email protected]>
Add a simple CAN resource. It may be used to determine the interface name by udev matching. Signed-off-by: Tomas Novotny <[email protected]>
Add an exporter part for the remotely accessible CAN. As discussed, the cannelloni is used as the underlying tunnel. According to the cannelloni documentation, it should be used only in environments where packet loss is tolerable. There is no guarantee that CAN frames will reach their destination at all and/or in the right order. XXX: The permission handling needs to be fixed, as the code requires running under a privileged user. Signed-off-by: Tomas Novotny <[email protected]>
The driver can connect to both local and remote CAN ports. For local ports, it sets up the interface. The driver is also helpful for identifying the interface name using udev. For remote ports, it creates a local vcan interface and establishes a connection to the exported resource through cannelloni. According to the cannelloni documentation, the speed of the network interface is limited by tc to prevent packet losses. XXX: See the code (many things to fix). Signed-off-by: Tomas Novotny <[email protected]>
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Description
This is a draft of basic CAN support. It is in RFC, as there are open questions, missing docs and tests, and moreover, it needs more testing. We plan to use it to remotely access the satellite's telemetry buses during development.
Local and remote CAN resources are added. Additionally, a simple CAN driver is added. The driver has very limited capabilities. For local use, it can set up the interface and tell you the interface name. For remote use, it establishes a transparent tunnel using cannelloni. With it, you can use the local virtual CAN interface. All the traffic is routed to the real interface on the other end.
Be aware, as cannelloni states in its doc:
I tested in the lab only. We will test it in production during September/October.
I see the main blocker: it requires root privileges on both sides (exporter and client; even for local use). What is the preferred way to handle privileged access? May we use
labgrid-raw-interface?Checklist
Reference issues: #1287 and #1289
This is a part of my work at VZLU AEROSPACE.