Now that mechanisms, tools, and methodologies are in place, it is finally time to start looking at the procedures required to run the software on the target. Booting up an embedded system is a process that often requires knowledge of the specific system, and the mechanisms in play. Depending on the target, there are a few indications we need to look for in the manual to find out what the system expects from the developer to successfully boot executables from the flash memory. This chapter focuses on the description of the boot process, with emphasis on the case of the Cortex-M microcontroller, which we decided to use as a reference platform. In particular, it covers:

• The interrupt vector table
  
• Memory layout
• Building and running the boot code
• Multiple boot stages