An Epoll Simulation for Non-Linux Systems Supporting Duplication and Cascade Nested Listening

Aiming at the problem that non-Linux RTOS systems lack a native epoll interface and are difficult to adapt to complex I/O applications, this paper proposes a method that supports epoll file dup and cascaded nested listening. In the user space, according to the epoll event type, all files including the sub-files managed by the epoll file nesting are added to the select read, write, and exception file descriptor set, and then select is executed and do the post-processing; the kernel space designs the character driver to store the listening file and event resources to provide a copy of the listening data for the dup system call, and implements the ioctl function to determine whether the file is an epoll file or not which to support cascade nesting capability. Experiments show that under the window manager based on Wayland graphics protocol, this method can efficiently categorize and cascade DRM graphics driver files, socket files, timer files, signal files, keyboard device files, mouse device files, touch device files under real-time system, and satisfy the concurrent processing of complex I/O requests of modern graphics system.