AX.25 amateur radio interfaces and TNC adapters
Linux drivers for amateur (ham) radio packet networking hardware: KISS-mode terminal node controllers on serial ports, 6PACK and BPQ Ethernet encapsulations, Baycom parallel/serial modems, YAM FSK modems, and Z8530 SCC cards. Most date to the 1990s, though KISS TNCs like the MFJ-1270X are still sold new in 2025.
recommendation
Already on the path to removal: a patch series titled "net: remove ax25 and amateur radio (hamradio) subsystem" was posted upstream in April 2026 to delete the entire stack. Although the subtree still saw routine maintenance in 2025 and KISS TNCs remain on sale, most hardware here is legacy ISA, parallel-port and serial gear, and Kconfig already marks some Baycom variants deprecated. Hams on modern Linux will need to track that thread or move to userspace alternatives.
repository signals
sources
- lore.kernel.org
Active upstream removal exists: "net: remove ax25 and amateur radio (hamradio) subsystem" posted on 2026-04-21 touches hamradio files including mkiss.
- lore.kernel.org
The directory was still receiving upstream maintenance in 2025 (example: hamradio helper conversion patch).
- mfjenterprises.com
A KISS-mode TNC product was still offered for sale recently, showing at least part of the hamradio hardware family remains available new.
- git.kernel.org
Kconfig describes MKISS as supported by most modern TNCs, and also marks BAYCOM_SER_HDX as deprecated, indicating a mixed subtree with one still-relevant niche and several clearly legacy drivers.
codex reasoning notes (technical)
Not an early-exit case: this is a real driver subtree with module entry points. Evidence came from local shell inspection of drivers/net/hamradio/Kconfig and file list, lore_regex over patch subjects for recent hamradio touches, lore_file_timeline on drivers/net/hamradio/mkiss.c, and web search to an active MFJ KISS TNC product page; the git.kernel.org Kconfig URL is canonical recall for the same file inspected locally. Conclusion: deployments are niche and low, most non-MKISS devices are legacy ISA/parport/serial hardware, but there is now an explicit 2026 upstream removal series for the whole AX.25/hamradio stack, so this escalates from deprecate to remove despite some remaining KISS/TNC availability.