Due to a problem in the 1.0 release of the Intel® Acceleration Stack for Intel Xeon® CPU with FPGAs, if the AFU reads host memory at an invalid address, then the FPGA stops responding.
Verify your AFU is reading a valid host region. See Shared Memory APIs for a description of how to allocate and share system memory with an AFU. See the hello_fpga code example which shows use of these APIs.
If this condition occurs, then a power cycle of the system is required to recover.
A future release of the Intel® Acceleration Stack for Intel Xeon® CPU with FPGAs will allow the FPGA to continue to respond when the AFU reads an invalid host memory location.