This disclosure describes techniques for ensuring security in an integrated circuit system that includes a processor subsystem and a configurable-logic (e.g., FPGA) subsystem, which is capable of storing code executed by the processor. Techniques for utilizing the configurable-logic to control the process of booting a processor in the processor subsystem securely are described. Because the configurable-logic may be on the same die as the processor in the integrated circuit, the configurable-logic may securely boot the processor inside the security boundary of the package containing the die.