【作者】 高丰；

【导师】 姚庆栋；

【作者基本信息】 浙江大学 ， 通信与信息系统， 2002， 博士

【摘要】 随着芯片集成度的飞速提高，集成电路的设计已经进入SOC时代。使用软硬件协同设计的方法，系统芯片必然包括硬件和与之协同工作的软件。操作系统不仅能提高芯片的性能和可靠性，而且能改善设计的可重用性、减少设计的上市时间(Time-to-Market)，日益受到重视。本文以HDTV信源解码芯片为SOC原型，设计并实现了一个基于SOC的实时操作系统Iota。 与通常的嵌入式实时操作系统相比，基于SOC的RTOS既有共性，也有其特殊性。其共性表现在强调任务的实时性，采用实时调度算法以保证系统的多个任务能满足实时性的要求；其特殊性源于SOC给RTOS的设计带来新的课题。例如，SOC中的实时操作系统在设计上可以更灵活，采用软硬件协同设计的方法，可以将操作系统的部分功能转移到系统的硬件实现。此外，系统芯片存储容量通常有限，SOC的RTOS比通常的嵌入式要求有更小的存储空间。 本文采用软硬件协同设计的方法来设计在SOC中的实时操作系统。本文在分析总线仲裁单元的时间片调度的基础上，将操作系统的I／O管理的功能部分采用硬件实现。通过软硬件协同设计，提高操作系统的实时性能和芯片的吞吐量。 实时性能是RTOS的最重要的性能指标。本文根据HDTV信源集成解码芯片的工作原理，对MPEG-2协议中的TS流解复用任务和AC-3音频解码任务提出缓存驱动和时限驱动两种调度策略。在详细分析了缓存驱动调度策略下的调度参数(例如调度的粒度和任务优先级)对系统实时性能的影响后，本文确定操作系统的调度策略及其参数。 存储管理是操作系统的重要内容，本文根据硬件的RISC核的存储管理单元(MMU)的特点，设计并实现了一种简单的存储保护和共享机制。操作系统和应用程序分布在系统的核心态和用户态，系统的核心态和用户态之间不能互相访问，此外不同的任务通过其不同的任务号限制其互相访问。通过存储保护机制提高系统健壮性。 由于SOC设计的复杂性日益提高，SOC要求在多种异构的平台上进行验证，典型的如虚拟机平台和基于硬件的FPGA验证平台。本文分析了实时操作系统在SOC软硬件协同验证中的作用。通过RTOS将应用的分解为不同的层次化，只要改变平台相关的接口模块，就可以实现在不同的异构平台上的仿真。通过操作系统可以减少验证的工作量，加快开发的进程。更多还原

【Abstract】 With the quick development of deep sub micron semiconductor technology, more and more systems on chip (SOC) have been developed for real-time systems. With the methodology of hardware/software co-design, there must be the software parts as well as the hardware parts on SOC. There is a growing consensus that the real time operating system (RTOS) has become an indispensable part of SOC. The RTOS can not only improve the performance and reliability of the system, but also simplify the development and debugging of SOC. In this dissertation, the design and implementation of a SOC-based real-time operating system, named Iota, has been presented.Compared with the general embedded RTOS, the SOC-based RTOS has its own specialities. The SOC environment acquired new features for RTOS. For example, the hardware/software co-design brings new methodology for the SOC-based RTOS. Some functions of the RTOS can be implemented in hardware. Furthermore, the memory size of the SOC is small even compared to the embedded systems. The foot-print of the SOC-based RTOS should be smaller than the embedded systems.In this dissertation, the RTOS is designed with the hardware/software co-design methodology. The scheduling policy of the bus arbitration unit was been analyzed and the I/O function of RTOS was partly implemented in hardware. By this way the performance and the throughput of the SOC are increased.The RTOS should focus on the real-time properties of system. In this dissertation the TS demultiplex task and AC-3 decoding task in MPEG-2 protocol are scheduled by 2 policies. One is the buffer-drive policy and the other is deadline-drive policy. Some experiments have been done to confirm the policy and the arguments of the scheduling.The memory management is important in the OS. According to the features of the MMU of the RISC Core, a simple memory protection and share mechanism was designed in Iota. The RTOS is in kernel mode while the application is in the user mode, the direct access from the user mode to kernel mode is denied and the access from one application program to another application is prohibited too. The memory protection and share mechanism can improve the reliability of the system.A new methodology for the hardware/software cosimulation using RTOS was introduced in this dissertation. The complexity of SOC required the different simulation platform. The RTOS is useful to build a hierarchical structure of the application, thus the application can be tested on different simulation platform with little modification. The RTOS can accelerate the simulation progress in SOC development.更多还原