Question $25$

$4$ pts

Select applicable statements about the layered OS architecture.

a layer can only use services provided by lower layers

defining the layers can be difficult because of circular dependencies between OS subsystems $($e$.$g$.$ CPU scheduling and backing$-$store driver$)$

simplifies construction and debugging

less efficient than a non$-$layered OS because a system call may involve repeated calls through the layers, necessitating repeated parameter copies and modifications