https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63760
--- Comment #2 from mojo at world3 dot net --- On platforms with this kind of architecture the default is to place everything in RAM, unless you specifically state otherwise. With Harvard style architectures different instructions are used to access RAM and program memory. GCC doesn't handle that natively, so you need to add things like PROGMEM or __flash to tell it where to store and how to access the data.
