RedHat contributes ~10% of total development: https://lwn.net/Articles/451243/ https://lwn.net/Articles/451243/ so from the point of view of RedHat a large pa

RedHat contributes ~10% of total development: https://lwn.net/Articles/451243/ https://lwn.net/Articles/451243/ so from the point of view of RedHat a large part of kernel development is actually free. Not actually 90% though since they don't care about all changes. Getting unrelated and often competing companies to cooperate in creating the infrastructure layer of software is a huge success case of open source.