挂在nfs根文件系统时出现如下报错:

[    1.939157] VFS: Cannot open root device "nfs" or unknown-block(0,255): error -6
[ 1.946989] Please append a correct "root=" boot option; here are the available partitions:
[ 1.955765] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,255)
[ 1.964493] ---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,255) ]---

根据内核日志来看bootargs是设置正确的,经过多方排查是以下配置没开启:

CONFIG_ROOT_NFS