-> 0x1000d04f5 <+213>: mulxq (%rsi), %r9, %rax You have configured your GMP for a too new CPU. The mulx instruction is available in Intel Broadwell, Skylake and newer, and in Amd Excavator, Zen. Presumably, you have configured GMP on a new system and then run it on an older system. -- Torbjörn Please encrypt, key id 0xC8601622