I would have thought that you can give Hatari directly the Linux serial device file, but that of course assumes that you've made sure that your Linux and Atari side serial settings match (speed, bits etc).
tschak909 wrote:also worth mentioning, that RS232 emulation doesn't work on Windows AT ALL because of its use of stdio file functions for opening the serial port (the windows com devices only open with the win32 API functions.)
Unfortunately nobody has contributed support for that.
(None of Hatari developers has/uses Windows, so any Windows features and testing of them needs to come from somebody else. Hatari Windows builds are done on Linux with MinGW. Any testing done for them needs to come from outsiders.)