Group ID to map to 0 (group root)


Linux Kernel Configuration
└─>Group ID to map to 0 (group root)
In linux kernel since version 2.6.14 (release Date: 2005-10-27)  
If INITRAMFS_SOURCE points to a directory, files owned by this GID
(-1 = current group) will be owned by root in the resulting image.

If you are not sure, leave it set to "0".