RISC-V 从这里开始

RISC-V：读作risk-five，是一个开源的CPU指令集架构

zephyr：开源 *** 作系统

linux：没什么好说的。

risc-pk：The RISC-V Proxy Kernel。解释如下：is a lightweight application execution environment that can host statically-linked RISC-V ELF binaries.  It is designed to support tethered RISC-V implementations with limited I/O capability and and thus handles I/O-related system calls by proxying them to a host computer.

BBL ：the Berkeley Boot Loader。

linux相关开源基础库对RISC-V的支持

binutils: upstreamed (2.28 is the first release with RISC-V support)

gcc: upstreamed (7.1 is the first release with RISC-V support)

glibc: upstreamed (2.27 is the first release with RISC-V support)

linux kernel: upstreamed (the architecture core code went into

kernel 4.15kernel 4.19 contains all drivers necessary for booting a

simulated system to userland)

gdb: upstreamed in master (in the release process)

qemu: upstreamed (2.12 is the first release with RISC-V support)

步骤一：编译生成u-boot.elf文件

使用git clone命令从github上下载u-boot源码，注意使用主分支（master）,使用tar命令对下载的压缩文件解压，tar zxvf u-boot-digilent-2012.04-digilent-13.01.tar.gz。 如果下载的是zip文件用unzip u-boot-digilent-2012.04-digilent-13.01.zip

编译u-boot之前我们要先设置好交叉编译环境变量，设置环境变量方法为source settings64.sh（见第一篇文章），然后根据上图编译u-boot，使用命令make CROSS_COMPILE= arm-xilinx-linux-gnueabi-

编译完成后会在u-boot-Digilent-Dev目录下生成u-boot文件，我们要给其加上‘.elf’，并且预先拷贝到sd_image目录下。

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