I was wondering if there was any way to update the system from one revision to another without rebooting. What would it take to remove the reboot requirement?
In fact, the alert is only here to warn that packages will be activated on next boot. Since they are not, it can’t mess up with what you were doing in any way and you can keep on working normally. Understand that what we don’t talk about random software here but low level things like kernel or drivers that are allocating memory, irqs, etc. At some point you will always have to reboot to get those things clean. At least, unlike some system, you don’t have to do it (several times) right away for every piece of software that you install.
As long as what was updated isn’t sitting in memory in use, nothing. The problem arises when it’s running or in memory with its tentacles on other resources (files, buffers, etc). It can be done but its cleaner and easier to just reboot. This isn’t specific to haiku, as it’s a general problem that is eventually asked or tasked to any OS. All depends on how the system had been structured and integrated with its applications and libraries.