CC: redirected to xemacs-beta. Robert> Martin Buchholz writes: Robert> Hmm, I'm intrigued. What needs to change? You have to portably detect if an address is malloced or not. The most portable way is to link xemacs like firstfile.o ... lastfile.o and check addresses of objects relative to symbols in firstfile.o and lastfile.o. Then you have to fix pdump to remember when it's dumping objects, whether they were in malloced space. When it restores the contents of non-malloced memory, it restores them to the original location. This makes xemacs a little smaller at run time. We can also optimize Lisp_Subrs to be const (and therefore shared) objects by moving the docstring out of the Lisp_Subr into a dynamic hash table. Then you make sure the contents of Qnil is a static object, i.e. not malloced. Like Qunbound has static contents guts_of_unbound_marker or something. Do this consistently for all symbols, and maybe some other lisp objects, like Qunbound. Then, if not using union type, Qnil is just a constant pointer to static memory. So Qnil can be defined to be #define Qnil &guts_of_Qnil; /* since we have no tag bits */ Figure out how to make this work even when using union type (we can accept a slowdown when using union type).