搭建opensbi+kernel+rootfs及基本设备驱动开发流程

一.编译qemu 运行opensbi+kernel+rootfs

1.编译qemu-9.1.1

2.安装riscv64编译器

3. 编译opensbi

4.编译kernel

5.编译rootfs

设备驱动开发流程

1.安装 RISC-V 交叉编译工具链

2.驱动开发准备

3.编写简易中断控制器驱动（PLIC）

4.配置内核编译选项

5.编译并测试驱动

一.编译qemu 运行opensbi+kernel+rootfs

1.编译qemu-9.1.1

打开qemu官网https://www.qemu.org/，下载qemu-9.1.1.tar.xz

root@ser004576790432:~# mkdir risc-v 
root@ser132653590900:~/risc-v# wget https://download.qemu.org/qemu-9.1.0.tar.xz

安装依赖并执行安装：

root@ser132653590900:~/risc-v/qemu-9.1.0/build# apt-get install build-essential gcc g++ make pkg-config 
root@ser132653590900:~# apt-get install libglib2.0-dev libpixman-1-dev libslirp-dev zlib1g-dev \
libfdt-dev libsdl2-dev libgtk-3-dev ninja-build git
root@ser004576790432:~/risc-v#  apt install --reinstall policykit-1 
root@ser004576790432:~/risc-v# systemctl enable --now polkit.service 
root@ser132653590900:~/risc-v/qemu-9.1.0/#apt-get install python3-venv python3-pip python3-dev 
root@ser132653590900:~/risc-v/qemu-9.1.0/# python3 -m pip install tomli 
root@ser004576790432:~/risc-v/qemu-9.1.0# mkdir build 
root@ser004576790432:~/risc-v/qemu-9.1.0# cd build/
root@ser004576790432:~/risc-v/qemu-9.1.0/build# ../configure --enable-slirp --target-list=riscv64-softmmu  
root@ser132653590900:~/risc-v/qemu-9.1.0/build# make -j12 
root@ser132653590900:~/risc-v/qemu-9.1.0/build# make install 
root@ser132653590900:~/risc-v/qemu-9.1.0/build# ./qemu-system-riscv64 --version 
QEMU emulator version 9.1.0
Copyright (c) 2003-2024 Fabrice Bellard and the QEMU Project developers

2.安装riscv64编译器

root@ser132653590900:~/risc-v# sudo apt install gcc-riscv64-linux-gnu g++-riscv64-linux-gnu -y

3. 编译opensbi

root@ser132653590900:~/risc-v# git clone https://github.com/riscv-software-src/opensbi.git -b v1.5.1 cd opensbi
make CROSS_COMPILE=riscv64-linux-gnu- PLATFORM=generic all -j12

4.编译kernel

wget https://mirrors.ustc.edu.cn/kernel.org/linux/kernel/v6.x/linux-6.6.1.tar.gz
tar xf linux-6.6.1.tar.xz
cd linux-6.6.1
make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- defconfig#提前安装依赖
apt-get install -y flex bison libssl-dev libelf-dev bc make make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- -j12

5.编译rootfs

root@ser132653590900:~/risc-v# wget https://buildroot.org/downloads/buildroot-2024.11.2.tar.xz 
root@ser132653590900:~/risc-v# tar xf buildroot-2024.11.2.tar.xz 
root@ser132653590900:~/risc-v# cd buildroot-2024.11.2/
root@ser132653590900:~/risc-v/buildroot-2024.11.2# apt-get install libncurses-dev 
root@ser132653590900:~/risc-v# tar xf buildroot-2024.11.2.tar.xz 
root@ser132653590900:~/risc-v# cd buildroot-2024.11.2/
root@ser132653590900:~/risc-v/buildroot-2024.11.2# make menuconfig

修改完成保存退出。

更换kernel的源地址：

root@ser004576790432:~/risc-v/buildroot-2024.11.2# vi .config 
BR2_KERNEL_MIRROR="https://mirrors.ustc.edu.cn/kernel.org/"
#中科大镜像

配置之后进行编译：

#安装依赖
apt-get install unziproot@ser132653590900:~/risc-v/buildroot-2024.11.2# FORCE_UNSAFE_CONFIGURE=1 make -j$(nproc)

编译时间较长。

编译完成后进行测试：

root@ser004576790432:~/risc-v# vi run.sh 
#!/bin/bashqemu-system-riscv64 \-M virt \-smp 4 \-m 4G \-kernel linux-6.11.4/arch/riscv/boot/Image \-initrd buildroot-2024.11.2/output/images/rootfs.cpio \-append "root=/dev/ram" \-display none \-serial stdio \-device virtio-scsi-device \-device virtio-net-pci,netdev=net0 \-netdev user,id=net0root@ser004576790432:~/risc-v# chmod +x run.sh 
root@ser004576790432:~/risc-v# sh run.sh

设备驱动开发流程

1.安装 RISC-V 交叉编译工具链

## riscv64-unknown-elf-gcc 是 裸机（Bare-metal）工具链，默认不支持动态链接和 Linux 内核的某些特性， 使用了针对裸机（bare-metal）的 RISC-V 工具链riscv64-unknown-elf-来编译 Linux 内核，会导致动态链接和共享库支持缺失建议换成gcc-riscv64-linux-gnu
apt-get install gcc-riscv64-linux-gnu

2.驱动开发准备

# 进入内核源码目录
cd risc-v/linux-6.6.1# 创建驱动代码目录
mkdir drivers/mydrivers

3.编写简易中断控制器驱动（PLIC）

创建文件 drivers/mydrivers/plic_driver.c：

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>static irqreturn_t plic_irq_handler(int irq, void *dev_id) {printk(KERN_INFO "PLIC Interrupt Received!\n");return IRQ_HANDLED;
}static int plic_probe(struct platform_device *pdev) {int irq = platform_get_irq(pdev, 0);if (request_irq(irq, plic_irq_handler, 0, "plic-mydriver", NULL)) {dev_err(&pdev->dev, "Failed to request IRQ %d\n", irq);return -EIO;}return 0;
}static const struct of_device_id plic_ids[] = {{ .compatible = "riscv,plic0" },{ /* sentinel */ }
};static struct platform_driver plic_driver = {.driver = {.name = "plic-mydriver",.of_match_table = plic_ids,},.probe = plic_probe,
};module_platform_driver(plic_driver);MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");

4.配置内核编译选项

编辑 arch/riscv/configs/defconfig：

CONFIG_MYDRIVERS_PLIC=y

创建 drivers/mydrivers/Kconfig：

config MYDRIVERS_PLICtristate "My PLIC Interrupt Driver"default yhelpSimple PLIC interrupt controller driver.

修改 drivers/mydrivers/Makefile：

obj-$(CONFIG_MYDRIVERS_PLIC) += plic_driver.o

5.编译并测试驱动

cd risc-v/linux-6.6.1
make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- distclean
make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- defconfig
# 使用 Linux 工具链重新编译
make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- -j$(nproc)#启动测试
qemu-system-riscv64   -M virt   -kernel arch/riscv/boot/Image   -initrd ../buildroot-2024.11.2/output/images/rootfs.cpio   -append "root=/dev/ram console=ttyS0"   -nographic   -serial mon:stdio

检查验证：