Posix compliance is a standard that is been followed by many a companies. I have few question around this area, 1. does all the file systems need to be posix compliant? 2. are applications also required to be posix compliant? 3. are there any non posix filesystems?
In the area of "requires POSIX filesystem semantics" what is typically meant is:
Sometimes it also means symlink/hardlink support as well as file names and 32bit file pointers (minimum). In some cases it is also used to refer specific API features like fcntl()
locking, mmap()
or truncate()
or AIO.