Genio 720 EVK: can0 gets an IPv4 address/default route and TX dropped keeps increasing

Yocto
1

Genio 720 EVK: can0 gets an IPv4 address/default route and TX dropped keeps increasing

Hi,

We found an issue with can0 on the Genio 720 EVK and would like to ask for your help to confirm the cause.

Test environment

  • Board: MediaTek Genio 720 EVK

  • OS: Rity Demo Layer 25.1.1-release (scarthgap), Yocto

  • Kernel: Linux 6.6.92 PREEMPT_RT

  • CAN: MCP2518FD, can0

Our application uses Linux SocketCAN (PF_CAN) to send and receive CAN/CAN-FD frames. Although can0 is represented as a network interface in Linux, we do not use it for normal IP networking. We expect can0 to be used only for SocketCAN.

However, on the default Genio 720 EVK system, we can reproduce the following behavior.

First, can0 is assigned an IPv4 address:

# ip -br addr
can0    UP    169.254.185.103/16

The default route is also configured to use can0:

# ip route
default dev can0 scope link src 169.254.185.103 metric 1001003
169.254.0.0/16 dev can0 scope link src 169.254.185.103 metric 1003

In addition, when checking:

# ip -details -statistics link show can0

we can see that TX dropped keeps increasing. For example, shortly after boot:

TX:  bytes packets errors dropped carrier collsns
         0       0      0      98       0       0

Our understanding is that some traffic is reaching the TX path of can0, but is then dropped without being transmitted as a valid CAN frame.

Since CAN/CAN-FD is an important interface for our application, we are concerned that some other network-layer traffic may be reaching the CAN interface.

Could you please help us confirm which part of the Yocto system is assigning the 169.254.x.x address and default route to can0, and why the TX dropped counter keeps increasing?

Thanks.