In what ways is the modular ke

The modular kernel approach requires subsystems to interact with each other through carefully constructed interfaces that are typically narrow(in terms of the functionality that is exposed to external modules).The layered kernel approach is similar in that respect.However,the layered kernel imposes a strict ordering of subsystems such that subsystems at the lower layers are not allowed to invoke operations corresponding to the upper-layer subsystems.There are no such restrictions in the modular-kernel approach,wherein modules are free to invoke each other without any constraints.