efi_getnextvariablename
struct efi_getnextvariablename __user *getnextvariablename_user;
struct efi_getnextvariablename getnextvariablename;
getnextvariablename_user = (struct efi_getnextvariablename __user *)arg;
_IOWR('p', 0x07, struct efi_getnextvariablename)