> The Secure Enclave uses encrypted memory and includes a hardware random number generator. Its microkernel is based on the L4 family, with modifications by Apple.
https://images.apple.com/lae/privacy/docs/iOS_Security_Guide.pdf
なるほど。L4はiOSの要,というよりも起動時の専用OS?ROM?用のカーネルとして採用されてるっぽいな。