First of all, thank you for your answer. I had two S32G-VNP-RDB3 boards and connected GMAC to each other on a 1:1 link, and then proceeded with frame preemption. Core proceeded with M core. I proceeded without using loopback. At this time, I set the clock and settings like a picture, but I saw a phenomenon where the handshake for frame preemption did not occur at this time, just like tx,rx. I need a solution!

