yum update kernel kernel-tools kernel-tools-libs kernel-headers kernel-devel
#如果沒有成功寫入啟動選單,執行下面的命令會寫入啟動選單
rpm -e kernel-4.19.90-23.48.v2101.ky10.x86_64 kernel-core-4.19.90-23.48.v2101.ky10.x86_64 --nodeps
yum install kernel
#回退
grub2-set-default 1
#檢視啟動選單
grubby --info=ALL
grubby --default-kernel
grubby --default-index