The interview process is tailored more for a grad rather than a senior. The interview panel didn’t acknowledge the fact that I've already been in the industry for 10 years working on complex systems with High Performance SoCs and for past 3 years not been working as extensively at chip level. i.e. catching system exception, analysing disassembly, rather our company already has an error trap API which has similar function.

One of the questions, how would I create a memory management unit in software. I gave my conceptual implementation how this would involve memory address check, boundaries and tlb function in software. Also I mentioned that it would be painfully slow and hamper the core. They weren't convinced of the details I've given.

Some questions were trying intentionally to intimidate you. Like where would I use volatile?, where variable should not be optimized. I gave an example of ADC converter, peripheral status registers where hardware can modify the bits. They weren't convinced.

There was a question about interrupt latency and what counts as full latency. I've explained about from

• MSB synchronisation of any ongoing instruction,
• saving the background task's stack onto the registers so foreground can load its registers on the stack,
• Handler fetching the ISR from a memory address,
• Completion and unloading of foreground's stack. They didn’t look convinced.

One question that did trip me, regarding security encryption process on embedded devices, i.e. secure boot, hashing, RSA etc. I explained the process to the best of my knowledge but I believe it was quite shallow. I acknowledged I haven't worked as extensively on the embedded devices security side of things even though secure embedded development is listed in my CV.

There were questions about trust zone. Again I explained the overall process that it's a hardware controlled process. I’ve talked about my experience working with trustzone on zynq 7000, how we assert certain bit in a register to grant access to peripherals, memory access etc. They weren’t convinced, wanted the name of the register and the specific bits which I couldn’t remember on top of my head.

The panel didn’t look at the overall skills, knowledge and external attributes like attitude under pressure. Overall the process felt like they're looking for a generic number to fill a seat rather than an engineer for a specialised domain who can bring innovation and creativity.

Interrupt latency

Trustzone

Secure boot

Volatile keyword use cases.