The XREL/XDEF's to share are even optinal, basically with a dummy prm file to satisfy the linker, it is possible to combine an HC12 absolute asm file and a XGATE absolute asm file in a single project. Shared addresses can be defined via EQU's in a include file consumed by both (or one can defined it via XDEF in one and the other one use it via XREF as suggested by Kef).
A minimal prm might look like this (Note that if everything is allocated absolutely, then nothing will be allocated in DEFAULT_RAM/DEFAULT_ROM. So those segments can be placed anywhere, the linker just insists that they exist and have at least a byte available and they must not overlap with anything allocated.
Mini prm for use with absolute XGATE/HC12 assembly code:
NAMES ENDPLACEMENTDEFAULT_RAM INTO NO_INIT 0x0000 SIZE 1; DEFAULT_ROM INTO READ_ONLY 0x0001 SIZE 1; ENDSTACKSIZE 0INIT Entry
Of course it is also possible to just use relocatable code only, the wizard generated a working project for this....
Daniel