While the Linux kernel has been seeing preparations from NVIDIA for 1.6 Tb/s networking in preparing for next-generation super-computing, the kernel has still retained support to now for the High Performance Parallel Interface. HIPPI was the standard for connecting supercomputers in the late 1980s and a portion of the 1990s with being the first networking standard for near-Gigabit connectivity at 800 Mb/s over distances up to 25 meters. But HIPPI looks like it will be retired from the mainline kernel with Linux 7.0.

HIPPI has been in the Linux kernel all the time even though for decades it was replaced by higher speed Ethernet and Fibre Channel connectivity in high-end hardware for networking. Modern consumer hardware has robust Gigabit Ethernet and the likes of 2.5Gb/s, 5Gb/s, and 10Gb/s even becoming more common. For its time HIPPI was great for connecting supercomputers but it’s past due for retirement from the Linux kernel.

This commit to the Linux networking subsystem’s "net-next" Git branch removes the HIPPI support from the Linux kernel along with the RoadRunner HIPPI driver. This frees the kernel of nearly three thousand lines of unmaintained code that likely hasn’t seen any real use in years. The commit comment noted:

"HIPPI has not been relevant for over two decades. It was rapidly eclipsed by Fibre Channel, and even when it was new, it was confined to very high-end hardware. The HIPPI code has only received tree-wide changes and fixes by inspection in the entire Git history. Remove HIPPI support and the rrunner HIPPI driver, and move the former maintainer to the CREDITS file. Keep the include/uapi/linux/if_hippi.h header because it is used by the TUN code, and to avoid breaking userspace, however unlikely that may be."

With the removal in net-next, it should be submitted as part of the networking changes for the upcoming Linux 6.20~7.0 merge window in February.