Ubuntu 切换 kernel

查看已安装的 kernel

$ dpkg -l | grep linux-image
ii  linux-image-4.15.0-45-generic              4.15.0-45.48~16.04.1                            amd64        Signed kernel image generic
ii  linux-image-4.15.0-88-generic              4.15.0-88.88~16.04.1                            amd64        Signed kernel image generic

查看当前使用的 kernel

$ uname -r
4.15.0-88-generic

查看 grub 配置信息

$ vim /boot/grub/grub.cfg
...
submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-1aedbe15-d824-41c6-8e0f-37999910dd79' {
    menuentry 'Ubuntu, with Linux 4.15.0-88-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-88-generic-advanced-1aedbe15-d824-41c6-8e0f-37999910dd79' {
      ...
    }
    menuentry 'Ubuntu, with Linux 4.15.0-88-generic (upstart)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-88-generic-init-upstart-1aedbe15-d824-41c6-8e0f-37999910dd79' {
      ...
    }
    menuentry 'Ubuntu, with Linux 4.15.0-88-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-88-generic-recovery-1aedbe15-d824-41c6-8e0f-37999910dd79' {
      ...
    }
    menuentry 'Ubuntu, with Linux 4.15.0-45-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-45-generic-advanced-1aedbe15-d824-41c6-8e0f-37999910dd79' {
      ...
    }
    menuentry 'Ubuntu, with Linux 4.15.0-45-generic (upstart)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-45-generic-init-upstart-1aedbe15-d824-41c6-8e0f-37999910dd79' {
      ...
    }
    menuentry 'Ubuntu, with Linux 4.15.0-45-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-45-generic-recovery-1aedbe15-d824-41c6-8e0f-37999910dd79' {
      ...
    }
}

Ubuntu 默认会使用最新版本 kernel 4.15.0-88-generic，为了将其切换到 4.15.0-45-generic，做如下更改

$ sudo vim /etc/default/grub

原始内容为

...
GRUB_DEFAULT=0
...

改为

GRUB_DEFAULT='Advanced options for Ubuntu>Ubuntu, with Linux 4.15.0-45-generic'

更新 grub，并重启机器

$ sudo update-grub
$ sudo reboot

再次查看当前使用的 kernel

$ uname -r
4.15.0-45-generic

完。