On Fri, Jul 31, 2020 at 05:00:12PM +0200, Arnd Bergmann wrote: > The majority of the code in the kernel deals with hardware that was made > a long time ago, and we are regularly discussing which of those bits are > still needed. In some cases (e.g. 20+ year old RISC workstation support), > there are hobbyists that take care of maintainership despite there being > no commercial interest. In other cases (e.g. x.25 networking) it turned > out that there are very long-lived products that are actively supported > on new kernels. > > When I removed support for eight instruction set architectures in 2018, > those were the ones that no longer had any users of mainline kernels, > and removing them allowed later cleanup of cross-architecture code that > would have been much harder before. > > I propose adding a Documentation file that keeps track of any notable > kernel feature that could be classified as "obsolete", and listing > e.g. following properties: > > * Kconfig symbol controlling the feature > > * How long we expect to keep it as a minimum > > * Known use cases, or other reasons this needs to stay > > * Latest kernel in which it was known to have worked > > * Contact information for known users (mailing list, personal email) > > * Other features that may depend on this > > * Possible benefits of eventually removing it We had this once, in the form of feature-removal-schedule.txt. It was, itself, removed in commit 9c0ece069b32e8e122aea71aa47181c10eb85ba7. I *do* think there'd be value in having policies and processes for "how do we carefully remove a driver/architecture/etc we think nobody cares about". That's separate from having an actual in-kernel list of "things we think we can remove".
