I managed to use the FatFS (the version included in KSDK 1.0.0) on a FRDM-K64F baremetal without PE (but with KSDK 1.0.0 and KDS 2.0.0).
All works (I'm still trying to understand how the driver write to the sdhc, when to use f_sync, etc...maybe another post for that), but the SDHC bus width is set to 1bit.
I tried to force the bus to 4bit (the sdhc card supports it), but then I have an error (FR_DISK_ERR) when trying to open a file.
Since it should improve the performances I really wish to use the 4bit bus.
Best Regards Giacomo