Key Learnings from Pre-Silicon Safety Compliant Bootrom Firmware Development

Safety needs of real-time embedded devices are becoming a must in automotive and industrial markets. The BootROM firmware being part of the device drives the need for the firmware to adhere to required safety standards for these end markers. Most software practices for safety compliance assume that software development is carried out once the devices are available. The BootROM firmware development discussed in this paper involves meeting safety compliance need while device on which it is to be executed is being designed concurrently. In this case, the firmware development is done primarily on pre-silicon development environments which are slow and developers have limited access. These aspects present a unique challenge to developing safety compliant BootROM firmware. Hence, it is important to understand the challenges and identify the right methodology for ensuring that the firmware meets the safety compliance with right level of efficiency. The authors in this paper share their learnings from three safety compliant BootROM firmware development and propose an iterative development flow including safety artefacts generation iteratively. Concurrent firmware development along with device design may sound risky for iterative development and one may wonder it may lead to more effort but the learnings suggests that iterative development is ideal. All the three BootROM firmware development has so far not resulted in any critical bugs that needed another update of the firmware and refabrication of the device.