some.exe have data say:
IniFileName db "..\file.ini",0

and in my.dll have a function that needs the access to IniFileName

whenever i try to compile my.dll i get an errors saying:
undefined symbol "IniFileName"

so the solution is to define it in my.dll and if i defined it here then some.exe cant be compiled.

so how could i share important data between these two modules?

not sure if its possible using .inc file, and if so then i still dont know how

The DLL contains procedures (functions) that the exe calls during run-time. If some of these functions needs memory pointers from the exe, they must be passed as an argument when the exe calls the DLL function.

i got two ways, either by pushing it on the stack or lea (load effective address)
so thanks jf.