Research And Implementation Of Microkernel Operating System For Multi-core Environment

With the continuous development of the embedded field and the continuous optimization of the processor architecture,multi-core processors have been widely used due to their high performance,low power consumption,low cost and other advantages.At the same time,in the era of the IOT,the embedded devices are facing more and more risks and challenges,and not only need to improve the reliability and safety of the device,but also need high scalability.Becase of the architecture characteristics,the microkernel has the advantages of small code size,high scalability,safety and reliability,and is very suitable for embedded devices.Therefore,based on the mginkgo microkernel developed by my teaching and research section,this thesis designs and implements a microkernel operating system for multi-core environments.This thesis conducts in-depth research and analysis on multi-core processors,multi-core operating systems,multi-core hardware mechanisms and micro-kernel technology.Combined with the characteristics of mginkgo micro-kernel,this thesis proposes an SMP multi-core extension solution to solve the operating mode and multi-core startup in the multi-core operating system,mutually exclusive access to shared resources,and communication between cores.It mainly contains the following seven modules:(1)In the multi-core startup and initialization,a temporary primary-secondary relationship is used to complete the initialization of the system;(2)In the synchronization and mutual exclusion between cores,this thesis studies and uses the Exclusive Monitor mechanism to design and implement atomic operations and spinlocks;(3)In the interrupt management,this thesis uses the General Interrupt Controller to process external interrupts,local interrupts and inter-core interrupts,and realizes the triggering,transmission and processing of inter-core interrupts;(4)In the inter-core communication,this thesis divides this communication into two parts: signal communication and data communication for processing,and then combine the inter-core interrupt with shared memory to provide core sleep,core wake-up,task migration,and task migration,thread kill,function call and IPC communication between cores and other functions;(5)Clock management records the total operating time of the system,and realized the clock interrupt function;(6)Task management realizes the division,organization and scheduling of tasks in the system,and adopts three steps of load monitoring,balanced decision-making,and task migration to complete the load balance on multiple cores;(7)In the cache consistency module,this thesis follows the MESI protocol and uses the SCU provided by the hardware platform to ensure the consistency of the cache on each core.Finally,the functional test,performance test and system throughput test of the microkernel were completed on the i.MX6Q(4-core ARM Cortex-A9 SoC)development board.Through the analysis of the test results,it is found that the microkernel operating system designed and implemented in this thesis can adapt to the needs of the multi-core environment and give play to the high performance and high throughput advantages of the multi-core processor.