Speeding up boot process for embedded system

[heathkit]

I'm using gentoo in an embedded concept, and would like to speed up my boot process. I'm not really interested in parellizing it. What I want to know is how much can I cut out. My goal is to get from power on to a serial console running in as little time as possible.

[PowerFactor]

You can cut out anything you don't need.
In other words it depends on how your system is set up and what capabilities it needs to have.
At the lowest extreme you can even get rid of init altogether and just have the kernel start a shell. Of course that only works well for a very basic system.