Map different memories in standard C

I'm working developing some embedded system with an 8051 at work. Today, all codes are written with IAR, which manage the different memories of the micro with some keywords like __xdata, __pdata, etc...

We're starting with unit testing using the framework Ceedling and I think that the best way of testing my units is making a native executable (http://ift.tt/1KBGuUw) and test in my linux and then, once my soft is done, compile it for the 8051.

My problem now is that I don't know how to map the different types of memories of the micro without using the IAR keywords. Does anyone have this problem?