The module rtl_posixio.o implements the /dev filesystem. It provides unix like (open(), read(), write(), ...) functions to access device driver services, and drivers can be registered with the function: rtl_register_rtldev().

Current implementation provides the following devices: /dev/rtf, /dev/mem and /dev/ttyS

RTLinux do not provide any block device nor regular filesystem implementation. Since the background RTLinux process is the Linux kernel, RTLinux designers choose not to include non-realtime features that are already available and usable.