Porting Epics to L4-linux Based System

Experimental Physics and Industrial Control System (EPICS) is now widely used for many accelerator control systems. While the current and the former versions of EPICS have required VxWorks to run core software on Input/Output Controllers (IOCs), the next version (R3.14) is to be portable to many other platforms. Considering the recent trend toward Linux, it is an attractive candidate for the port. However, the Linux kernel cannot ensure real-time responsiveness because it dose not preempt the execution from a process that is running in the kernel. As an alternative, we adopted L4Linux, a port of Linux onto a real-time micro-kernel (L4), as the platform. With some adaptation, L4-Linux allows any EPICS thread to benefit from either the real-time scheduling by L4 or the many functions of Linux. The adaptation of L4-Linux to the real-time use, the interface libraries between the IOC software and L4Linux, and a library to support the VMEbus are described. A preliminary result of the measurement of interrupt latency is also presented.