Based on this excellent answer on changes to init daemons: What is Upstart?
...it seems like modern init replacements including upstart and systemd have added functionality because they are event driven etc. The common example that is given is the one using a USB stick as described here.
- The addition or removal of USB flash drives and other portable storage / network devices while the machine is running
- The discovery and scanning of new storage devices, without locking the system, especially when a disk may not even power on until it is scanned
- The loading of firmware for a device, which may need to occur after it is detected but before it is usable
Upstart's event-driven model allows it to respond to events asynchronously as they are generated.
https://en.wikipedia.org/wiki/Upstart
My question is for example what was exactly the difference in behavior when inserting a USB stick and using the traditional System V init. What had to be done?
Since it provides advantages with loading firmware - does this relates to, does part of the job or replaces need for drivers for peripherals?