Embedded Systems Architecture

The code region

The lowest 512 MB of the addressing space in a Cortex-M microcontroller is reserved for executable code. Targets that support XIP always map the flash memory within this area, and the memory is generally not writable at runtime. In our previous examples, the .text and .rodata sections are mapped within this region as they remain constant during the execution of the software. Additionally, the initial values of all non-zero defined symbols are placed in this area and need to be explicitly copied and re-mapped to a writable segment in order to modify their value at runtime. As we already know, the interrupt vector table (IVT) is usually located at the beginning of the mapped section, starting at address 0. Multiple flash memory ...