Ah, thanks, I had some idea about RTD, but I had not been able to find it in the docs. It is supported since 68010 and is still here on 68060.
Oops, I have old copy of Programmer's Reference Manual, 68060 didn't exist yet ;-)
Unfortunately, RTD is not suitable for traps, because traps are exceptions and they push SR afer the return address (and also a format word on 68010+, and maybe some filler bytes on ColdFire). Also, the traps must be callable from user and supervisor mode, so they have to deal with the supervisor SP and USP...
I thought so. This is probably argument I was looking for, thanks.
So RTD is designed to implement stdcall on standard functions, not OS calls through traps.
So we, hypothetically, need something like RTE #size, right?
And also, the TOS was designed for bare 68000, with no support for RTD.
True, true.