Amount of data copied from flash to RAM between calls to the minidriver
unsigned mdriver_max = KILO(16);
The mdriver_max is a global variable defined in the file mdriver_max.c in the startup code. It defines the amount of data (in bytes) that's copied from flash to RAM between calls to your minidriver. The default value is 16 KB, but you might have to change it, depending on the timing requirements of your device, the processor speed, and the flash; see “Timing requirements” in the Writing a Minidriver chapter.
The KILO() macro, along with MEG() and GIG(), is defined in <startup.h>.