CNRV

为推广RISC-V尽些薄力

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Spike模拟Linux 5.3教程

作者:Liboya-CB, 2019年11月。

相关工具版本说明

环境变量设置

$ export  TOP=/home/<user>/Riscv           // 整个环境的顶层目录
$ export  RISCV=$TOP/riscv-tools/riscv-tc  // riscv compiler编译器安装目录,可换至其他目录
$ export  PATH=$PATH:$RISCV/bin

建议将一下环境变量专门设置到单独的文件中,每次使用时source对应文件。 如想确定变量是否为想要的目录,可以以类似echo $TOP的方式查看。

toolchain安装

按照riscv-gnu-toolchainriscv-pkriscv-isa-sim的步骤安装编译。

截止这一步骤,编译即可执行一个riscv程序,可以编译一个hello world 程序测试Toolchain,使用命令:spike pk hello 。

echo -e '#include <stdio.h>\n int main(void) { printf("Hello world!\\n"); return 0; }' > hello.c
riscv64-unknown-elf-gcc -o hello hello.c
spike pk hello

Linux Kernel

下载至$TOP,并通过riscv64-unknown-linux-gnu-进行编译。

make -j16 ARCH=riscv CROSS_COMPILE=riscv64-unknown-linux-gnu-

Busybox

下载至$TOP并解压:

curl -L http://busybox.net/downloads/busybox-1.26.2.tar.bz2 >busybox-1.26.2.tar.bz2
tar xvjf busybox-1.26.2.tar.bz2

进入busybox目录,使用make allnoconfig关闭所有busybox配置选项。再通过make menuconfig开启相关选项,包括:

CONFIG_STATIC=y, listed as “Build BusyBox as astatic binary (no shared libs)in BusyBox Settings Build Options
CONFIG_FEATURE_INSTALLER=y, listed as“Support –install [-s] toinstall applet links at runtime” in BusyBox Settings General Configuration
CONFIG_CROSS_COMPILER_PREFIX=riscv64-unknown-linux-gnu-,listed as “Cross Compiler prefix” inBusyBox Settings  Build Options
CONFIG_INIT=y, listed as “init” in Init utilities
CONFIG_ASH=y, listed as “ash” in Shells
CONFIG_ASH_JOB_CONTROL=n, listed as “Ash → Job control” inShells
CONFIG_MOUNT=y, listed as “mount” in Linux SystemUtilities
CONFIG_FEATURE_USE_INITTAB=y, listed as “Support reading aninittab file” in Init Utilities

配置结束后,采用make_rootfs.sh脚本来编译busybox,构建Root Disk Image,创建initramfs。

inittab

::sysinit:/bin/busybox mount -t proc proc /proc
::sysinit:/bin/busybox mount -t tmpfs tmpfs /tmp
::sysinit:/bin/busybox --install -s
/dev/console::sysinit:-/bin/ash 

make_rootfs.sh

CDIR=$PWD
if [ -z "$BUSYBOX" ]; then BUSYBOX=$CDIR/busybox-1.26.2; fi


if [ -z "$LINUX" ]; then LINUX=$CDIR/linux; fi

if [ -d "$BUSYBOX" ] && [ -d "$LINUX" ]; then
    echo "build busybox..."
    make -j$(nproc) -C "$BUSYBOX" 2>&1 1>/dev/null
    if [ -d rootfs ]; then rm -fr rootfs; fi
    mkdir rootfs && 
    cd rootfs
    mkdir -p  bin etc dev lib proc sbin sys tmp usr usr/bin usr/lib usr/sbin
    cp "$BUSYBOX"/busybox bin/
    ln -s bin/busybox ./init
    cp $CDIR/inittab etc/inittab
    echo "\
        mknod dev/console c 5 1 && \
        find . | cpio -H newc -o > "$LINUX"/rootfs.cpio\
        " | fakeroot &&
    if [ $? -ne 0 ]; then echo "build busybox failed!"; fi
else
    echo "make sure you have both linux and busybox downloaded."
fi

配置Linux并编译

进入kernel目录,使用命令make ARCH=riscv menuconfig进入图形化界面,配置:

CONFIG_VT_CONSOLE=n
Initramfs source file 输入Enter键将其更改为“<riscv_linux>/rootfs.cpio”
CONFIG_HVC_RISCV_SBI=y

进入Linux目录,编译Kernel,生成vmlinux:

make -j4 ARCH=riscv CROSS_COMPILE=riscv64-unknown-linux-gnu- vmlinux

重新进入riscv-pk目录编译,这步会将vmlinux包装至bbl中。

cd <riscv-pk>/build
rm -rf *
../configure  --prefix=$RISCV --host=riscv64-unknown-linux-gnu --with-payload=<riscv-linux>/vmlinux
make
make install

最后,执行spike bbl即可用spike模拟Linux。

说明

为何设置CONFIG_VT_CONSOLE=n的原因请参考该链接