The SDK provides callbacks for the application bond database functions, which can be replaced with user functions. However, the struct bond_db is defined in the app_bond_db.c file (not in the header) and the bond_db declaration is static in app_bond_db.c, so it is very difficult to provide meaningful user-defined replacements for the app_bond_db_callbacks without modifying the SDK files. I try not do do this because it makes upgrading the SDK very difficult when custom modifications have been made.
Our application will store the bond DB in the flash memory of another processor in the design, so the canned SPI_FLASH and I2C_EEPROM functions are not suitable. It would be really nice if the SDK provided a function to retrieve the bond_db structure address and size, which would allow override of the default callbacks without modifying the SDK. As it is now, I will need to modify the SDK to provide this function.