Understanding of the upper half and lower half of Linux kernel

Understanding of the upper half and lower half of the Linux kernel-general Linux technology-Linux programming and kernel information. The following is a detailed description. The activities of the operating system core during running can be divided into two parts: top half (top half) and bottom half (bottom half). The top half is divided into applications that provide system calling or self-trapping services, it is a synchronization service, caused by the currently executed process. It is executed in the context of the current process and allows direct access to the data structure of the current process;

The lower part is a subroutine that processes hardware interruptions and is an asynchronous activity. The call and execution of these subroutines are irrelevant to the current process.

The upper part is allowed to be blocked because the current process is blocked; the lower part is not allowed to be blocked because blocking the lower part causes blocking of an innocent process or even the entire core.