Translations:EFI stub/90/en
From Gentoo Wiki
Note
On some systems /efi/EFI or /efi/efi (in lowercase) may already exist (assuming the ESP is mounted at /efi). The FAT file system of the EFI System Partition (ESP) is not case-sensitive, but case-preserving (VFAT). With the default VFAT mount options, the above command will work in both cases. See the case sensitivity section in the FAT article for further details.
On some systems /efi/EFI or /efi/efi (in lowercase) may already exist (assuming the ESP is mounted at /efi). The FAT file system of the EFI System Partition (ESP) is not case-sensitive, but case-preserving (VFAT). With the default VFAT mount options, the above command will work in both cases. See the case sensitivity section in the FAT article for further details.