ubuntu 23 连接正点imx6ull的uboot网络设置（nfs和tftp）

1. 由于使用ubuntu23，无法连接正点的imx6ull的uboot，因为这个uboot里面的nfs是v2，ubuntu23内核是6.5不支持uboot v2。
2. 配置/etc/default/nfs-kernel-server
   sudo vim /etc/default/nfs-kernel-server
   更改以下参数：
   RPCNFSDCOUNT="-V 2 8";
   RPCMOUNTDOPTS="-V 2 --manage-gids";
   RPCSNFSDOPTS="--nfs-version 2,3,4 --debug --syslog";
   有的帖子说是更改
   RPCSVCGSSDOPTS="--nfs-version 2,3,4 --debug --syslog";
   试过都不行
3. 只能降级内核到Linux 5.19.0-41-generic
4. uname -a是查看内核版本命令
5. dpkg --get-selections | grep linux-image查看已经安装的内核版本，说明linux可以安装内核，但不需要启动
6. sudo apt-get install linux-image-5.19.0-41-generic是安装内核命令，由于镜像源不足所以报告找不到包的错误。于是更新镜像源使用命令：sudo nano /etc/apt/sources.list

   1. deb http://security.ubuntu.com/ubuntu trusty-security main
      deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse
      deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
      deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
      deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse

      deb http://mirrors.aliyun.com/ubuntu/ jammy main restricted universe multiverse
      deb-src http://mirrors.aliyun.com/ubuntu/ jammy main restricted universe multiverse
      deb http://mirrors.aliyun.com/ubuntu/ jammy-security main restricted universe multiverse
      deb-src http://mirrors.aliyun.com/ubuntu/ jammy-security main restricted universe multiverse
      deb http://mirrors.aliyun.com/ubuntu/ jammy-updates main restricted universe multiverse
      deb-src http://mirrors.aliyun.com/ubuntu/ jammy-updates main restricted universe multiverse
      deb http://mirrors.aliyun.com/ubuntu/ jammy-proposed main restricted universe multiverse
      deb-src http://mirrors.aliyun.com/ubuntu/ jammy-proposed main restricted universe multiverse
      deb http://mirrors.aliyun.com/ubuntu/ jammy-backports main restricted universe multiverse
      deb-src http://mirrors.aliyun.com/ubuntu/ jammy-backports main restricted universe multiverse
      deb https://mirrors.ustc.edu.cn/ubuntu/ jammy main restricted universe multiverse
      deb-src https://mirrors.ustc.edu.cn/ubuntu/ jammy main restricted universe multiverse
      deb https://mirrors.ustc.edu.cn/ubuntu/ jammy-updates main restricted universe multiverse
      deb-src https://mirrors.ustc.edu.cn/ubuntu/ jammy-updates main restricted universe multiverse
      deb https://mirrors.ustc.edu.cn/ubuntu/ jammy-backports main restricted universe multiverse
      deb-src https://mirrors.ustc.edu.cn/ubuntu/ jammy-backports main restricted universe multiverse
      deb https://mirrors.ustc.edu.cn/ubuntu/ jammy-security main restricted universe multiverse
      deb-src https://mirrors.ustc.edu.cn/ubuntu/ jammy-security main restricted universe multiverse
      deb https://mirrors.ustc.edu.cn/ubuntu/ jammy-proposed main restricted universe multiverse
      deb-src https://mirrors.ustc.edu.cn/ubuntu/ jammy-proposed main restricted universe multiverse
      deb http://mirrors.163.com/ubuntu/ jammy main restricted universe multiverse
      deb http://mirrors.163.com/ubuntu/ jammy-security main restricted universe multiverse
      deb http://mirrors.163.com/ubuntu/ jammy-updates main restricted universe multiverse
      deb http://mirrors.163.com/ubuntu/ jammy-proposed main restricted universe multiverse
      deb http://mirrors.163.com/ubuntu/ jammy-backports main restricted universe multiverse
      deb-src http://mirrors.163.com/ubuntu/ jammy main restricted universe multiverse
      deb-src http://mirrors.163.com/ubuntu/ jammy-security main restricted universe multiverse
      deb-src http://mirrors.163.com/ubuntu/ jammy-updates main restricted universe multiverse
      deb-src http://mirrors.163.com/ubuntu/ jammy-proposed main restricted universe multiverse
      deb-src http://mirrors.163.com/ubuntu/ jammy-backports main restricted universe multiverse

7. apt-get update这个命令用于同步本地的软件包列表与远程仓库的信息，即更新可用软件包及其版本的列表
8. 安装完linux-image-5.19.0-41-generic后，更改grub配置，sudo nano /etc/default/grub
9. 添加这个：GRUB_DEFAULT="Advanced options for Ubuntu>Ubuntu, with Linux 5.19.0-41-generic"(注意双引号），保存退出
10. sudo update-grub更新启动顺序，reboot
11. sudo nano /etc/nfs.conf更改nfs配置：
    1. udp=y
       vers2=y
12. 重启nfs
    1. /etc/init.d/nfs-kernel-server restart
    2. sudo systemctl stop nfs-server；sudo systemctl start nfs-server
    3. 
       sudo cat /proc/fs/nfsd/versions查看是否支持nfs v2
       rpcinfo -p | fgrep nfs 查看UDP是否打开。
13. tftp设置：/etc/xinetd.d/tftp设置中， server_args = -s -c /home/xxx/linux/tftp