The Proxy Kernel Implementation Based On RISC-V

RISC-V is a new general-purpose instruction set architecture that's modular,extensible,and royalty-free.It has a complete software stack,including the target machine implementation layer,the kernel layer,the library layer,the toolchain layer,and the application layer.As one of the important components of the RISC-V software stack,the kernel layer plays an important role in controlling hardware resources and supporting user programs.The RISC-V proxy kernel is a lightweight application execution environment that can host statically-linked RISC-V ELF binaries.However,since it only implements a subset of the Linux application binary interface,it is too simple to support multi-process programs.Compared with traditional kernels,the proxy kernel is lightweight,easy to use,and efficient.But the existing proxy kernel also has many shortcomings.In order to solve these shortcomings,a new kernel is implemented based on the existing RISC-V proxy kernel.The new kernel is implemented as follows: 1)In terms of function expansion,the new kernel further improves the system call and exception handling unit of the existing kernel,providing more powerful functional support for the system.2)In terms of interrupt handling,the new kernel adds clock interrupts and device interrupts to respond to asynchronous interrupt events in the system.3)In terms of memory management,the new kernel adds a memory management unit to the existing kernel to maintain the allocation and recovery of physical memory in the kernel.The new kernel also implements a three-level page table mapping from virtual memory to physical memory,and realizes a logical address space of 512 Gib.4)In terms of process management,the new kernel adds a process management unit to the existing kernel to realize process creation,execution,recycling,and switching.Based on the process management unit,the new kernel implements two lock mechanisms to maintain data consistency between processes.Finally,Through the illegal instruction test,the illegal address access test,the virtual memory test and the multi-process test,the function modules of the kernel are verified.In the hardware test environment based on Zed Board,the correct operation of the proxy kernel on Rocket Chip is realized through the front-end server.