实时响应的嵌入式系统虚拟化微内核架构

Real-Time Microkernel Architecture for Embedded System Virtualization

嵌入式系统的虚拟化要求实时性要求高的任务运行在实时(Real Time)的来宾操作系统上,非实时性的任务运行在GPOS(General Purpose)的来宾操作系统。现有的半虚拟化(PV)方案,实时性较差,无法满足嵌入式系统的要求。提出一个虚拟化微内核架构,在内存管理方面,设置三个内存特权级别,并启用域访问控制功能来禁止guest kernel的访问;实行中断虚拟化,提出虚拟GIC(vGIC)方案来控制中断;设置共享内存区,通过VM/VMM共享来解决大量的Hyper-call造成的开销问题;使用简单而优化的异步通信方法来代替传统的同步IPC模型来降低复杂度;在定时器方面,提出了一种高精度的定时器虚拟化方法来提高实时操作系统的可调度性;在调度器方面,采用基于优先级的抢占式循环策略。该架构可提高嵌入式系统在ARM处理器平台虚拟化的实时性。

Real-time tasks must operate on the real-time guest operating system,whereas non-real-time tasks must run on the GPOS(General Purpose)guest operating system.The current PV method has poor real-time performance and cannot match the needs of embedded systems.A virtual microkernel architecture is suggested in this study.Three memory permission levels are configured,and the domain access control function is enabled to prevent guest kernel access.To regulate interrupts,a virtual GIC(vGIC)is proposed.Set up a shared memory region via VM/VMM sharing to alleviate the overheads generated by a high number of Hyper-calls;a simple and efficient asynchronous communication approach is utilized to replace the standard synchronous IPC paradigm to minimize complexity.To increase the schedulability of real-time operating systems,a high precision virtualization approach of timer is presented.The scheduler employs a preemptive cycle technique based on priority.This design can increase the real-time performance of ARM processor-based embedded system virtualization.