It should be possible to link both memories together, however you need to take into consideration that you’d not be able to use the memory to its fullest. Some memory spaces are already mapped to a fixed address.
There’s no environment build or sample code that does this. All the information available is in these documents Intel® Quark™ Microcontroller D2000: Documentation . I’d suggest you to take a look at section 12 of Intel® Quark™ Microcontroller D2000: Datasheet . It would also be useful for you to check the \IntelSWTools\ISSM_2016.0.027\firmware\bsp\1.0\soc\quark_d2000\include\qm_soc_regs.h file.