hi :
    while in user mode, processes have their system calls intercepted and virtualized, in kernel mode, they are released from tracing and their system calls run directly in the host kernel.
what I want to know is since in kernel mode ,why the system calls run directly in the host kernel?
Does the UML kernel share the same space with the host kernel?
Since UML runs as a user process on the host OS, its UML kernel should run in the host user space.
namely, the UML kernel runs in the host user space. If it is true,how a system call runs in a user space?
eager to your answers.
 
thanks very much.