Why I am not able to build the CRC Nios II custom instruction example? - Why I am not able to build the CRC Nios II custom instruction example? Description When using the CRC Nios ® II custom instruction example in https://www.altera.com/support/support-resources/design-examples/intellectual-property/embedded/nios-ii/exm-custom-instruction.html in 17.1 there is a compiler error of undefined reference to ALT_CI_CRC_0_N. Resolution To fix this issue, the ALT_CI_CRC_0_N variable name in ci_crc.c need to be changed to ALT_CI_CRC_CUSTOM_INSTRUCTION_0_N. This is due to the earlier name set for the Nios ® II custom instruction component, as stated in Step 2. page 30 from this document; https://www.altera.com/en_US/pdfs/literature/ug/ug_nios2_custom_instruction.pdf A future fix will be applied on the software code files in coming 18.1 Custom Fields values: ['novalue'] Troubleshooting FB: 537634; False ['Nios® II Processor'] ['FPGA Dev Tools Quartus® Prime Software Pro'] 18.1 17.1 ['Programmable Logic Devices'] ['Nios® II Embedded Design Suite (EDS)'] ['novalue'] ['novalue']