I don't know how what your code looks like.

But why do you force a constant char to be stored in the code segment? Have you checked if you save any code size by making the constant into a physical entity stored in the flash, compared to being just a numeric value defined by #define or inside an enum {...} block? Having constant data forced into "code" is great when you may have printable text strings, structures representing the menu tree for an LCD etc. But I would not be in a hurry to try to force a one-byte constant into "code" since the compiler needs a number of code bytes whenever it is going to fetch this value into a register to be able to make use of the value.

And if you really do want to have it as a constant stored in the code segment, and that constant needs access from both banks - shouldn't you then make sure that it gets linked into the common bank? You must definitely don't gain anything from having it duplicated.