Wrong "stack"

Wrong Goal and also factually incorrect. uClinux has been booting on industrial controllers in
under 1 second to functional, completely running state for 10 years. And on processors running
very low double digit MHz clock speeds (and yes, from Motorola, now Freescale too). The key is not
so much replacing init with a single purpose application (that can help), but making a proper tiny
stack that does just what you need, of which init is a part. Thankfully, just what you need is not so
different as one might initially think from application to application.

If you need to do "tuning of the entire software stack" then you're using the wrong stack.

J.