Error when running MEMTEST.c

when i run thet memtest , I get the following error

Select Choice (a-b): [Followed by <enter>]b

Enter the name of the CFI flash device to be opened,

or just press <enter> to open "/dev/ext_flash"

>

-ERROR: could not open /dev/ext_flash

I see this listed in my system.h file and there is an init() call in my alt_sys_int.c

just not sure how to start debug ??