I saw that it uses the same software (trueffs - by m-systems) that also drives the extended rom.
I found the documentation of trueffs rather lacking, and incorrect.
hope that is not the reason for spirits recent troubles.
many of the ioctl's described in this document work different in reality than described, mostly parts that pass a pointer to a buffer in the ioctl's 'in' parameter, pass this pointer in reality in the 'out' parameter.
return values sometimes reflect the success of a call, and sometimes are unrelated.