So one of the big features in kernel 4.0 is the ability to update the kernel without rebooting. 16.04 has kernel 4.0. So therefore, is the no reboot feature enabled by default? Or if not, is there a way to enable it?
Ubuntu has livepatch, which is a livepatching service for Ubuntu 16.04.
It is now working
sudo snap install canonical-livepatch sudo canonical-livepatch enable TOKEN_FROM_ABOVE_LINK
On 20th October, 2016 Canonical officially announced the support for no reboot kernel patching, freely available on maximum three machines for a single user, check the article for details.
Yes, kernel hot patching is enabled in Ubuntu 16.04.
It was actually introduced in the first 4.0 series kernel on Ubuntu, with the 15.10 release, in October, 2015.
In a nutshell, any Ubuntu release currently having a official repository provided kernel (and mainline too) with version >=4.0 has live patching facility.
Note: Just to be clear, Ubuntu 16.04's kernel has the live patching capability, but Ubuntu offically does not provide any hot patch (as of now) as this answer mentioned.