OS Updating in Yocto

We are considering to use Yocto Build system for creating our own distro for our new project.

We have one query: How does OS Update works in Yocto Build System.

Suppose if I want to upgrade the following:

1. Bootloader ( u-boot )
2. Kernel Image ( zImage/bzImage )
3. Adding files in the root file system ( can be some scripts or executables )
4. Adding/Upgrading Packages ( E.g. Updating dropbear to the latest version )

How can we achieve this requirement . What are the things should we develop to achieve this feature.

Whether the updates are monolithic i.e., do we have to reflash everything like buildroot or partial updates only add the necessary things..

I see many suggest swupdate layer to include for this and there are many such tools I believe. Can you suggest which is the best one to use.

Thanks for your time and response

Which of the existing solutions is "the best" depends on your requirements, so this is something that you will need to decide yourself.

There is an overview page of solutions that work in combination with Yocto. It has links to further information: https://wiki.yoctoproject.org/wiki/System_Update