Samsung V1.3.0 Porting Manual page 23

If you didn't select the 'FAT32 & long file name' when you built the kernel image, this
command will success and RFS is able to support filenames with the native language in the 8.3
format.
If you selected the NLS support and the default codepage, this command will success if only
the default codepage is configured and built. For example, if the default codepage is
"codepage 437", then RFS supports filenames with the native language of 'cp437' character set.
If you selected the NLS support and didn't set the default codepage, this command will fail.
15 Linux RFS v1.3.0 Porting Guide