ok, I think I’ve figured out the situation.
Background, I have two frameworks in question here, one is running Debian Stable (11, bullseye), and the other is running rolling-release Fedora. Debian is running the 5.10.179-1 kernel, Fedora 6.2.14-300.
Some of this information is based on Fixing performance issues with Realtek RTL8156B 2.5GbE USB dongle in Ubuntu - CNX Software and Realtek USB FE / GBE / 2.5G / 5G Ethernet Family Controller Software - REALTEK
As far as I understand it:
- Minimum kernel needed for RTL8156* to work under cdc_ncm is >5.10,<=5.13
- The proper driver for this chip is the r8152 driver, but cdc_ncm will function (send and receive packets)
- Debian 11 doesn’t work at all (with behavior noted above)
- Newer distros do function, but my Fedora uses cdc_ncm, where it comes up in half-duplex mode
- The RTL8156B firmware is in debian bookworm+
- Unclear if the RTL8156B firmware is applicable to the RTL8156BG
- I think there’s missing modules.aliases (modalias) lines on both the driver and firmware sides
- A bunch of these issues will also apply to the A and B variants of the chip
I could go and learn how to write modalias strings, but I think it might be smarter at this point to hand it off to someone with more experience in these things.