I'm running RHEL 7.0 and I the system seems to have a problem talking to the Phi card.
This is what I see in lspci:
03:00.0 Co-processor: Intel Corporation Xeon Phi coprocessor 5100 series (rev ff) (prog-if ff)
!!! Unknown header type 7f
Kernel driver in use: mic
I've attached the micdebug log.