Thanks Greg.
I found out that this resulted from an error in my Kconfig file. I was
providing those functions, but they weren't getting compiled or linked due
to my config settings. I corrected that Kconfig file, reran 'make
menuconfig' and now my files are being compiled and linked.
There's stil
arm-none-eabi-ld:
/home/adam/src/nuttx/nuttx-sama5d2-xult/nuttx/arch/arm/src/board/libboard.a(sam_bringup.o):
in function `sam_bringup':
/home/adam/src/nuttx/nuttx-sama5d2-xult/nuttx/boards/arm/sama5/sama5d2-xult/src/sam_bringup.c:149:
undefined reference to `sam_sdmmc_sdio_initialize'
arm-none
