@Anders answer is complete exaustive and very good. The only thing I can add as a suggestion to you is to think on some things:
- Has your application an internet connection/USB/SD card to store a
complete new rootfs? Working with Linux embedded is not the like write a 128K firmware on a Cortex M3..
- Has your final user the capability to do the update work?
- Is your application installed in a accessible area remote controlled?
About the time you need to develop a complete/robust/stable solution is not a so simple question, but take notes that is a key point of an application that impact on the market feeling of your application. Especially in early days/month of first deploy where is usual to send updates to fix little/big youth bugs.
