Facebook Onsite-Systems Engineer-Need Advice

Hello, I recently had a phn screen with a manager and was asked 2 Leetcode medium questions to solve in 45 mins. I finished that and got selected for onsite in 3 weeks. The rounds are as follows:(5hrs): Systems (Linux/Unix) Systems Design Networking Coding HR Any advice on study material/video links will be highly appreciated. Also, can someone point me where to study for Systems round(which will be kernel level questions ) and Systems design round as I know they will be asked deeply.