[thisrod]

> that's a terribly limited API.

Plan 9's users consider that a feature. Standing boast: "GNU's compiler manual is bigger than our whole system!"

> I don't know enough about plan9 to suggest how, for example, notifications for device property changes could be added.

You'd add a virtual file named "ctl". Processes could open it and call read, which would block until something changed, then return with the notification.

Those processes will need threads that work. Plan 9's do.