I'm catching a SIGILL on POWER7 ppc64-le machine. I compiled the source with -mcpu=power8 so I could enable some builtins I may need. Use of the builtins is guarded at runtime. (This is the classic distro model, where most source code is compiled for a minimum machine but higher ISAs are guarded at runtime). GCC converted some C code into POWER8 code. The SIGILL is happening in the function prologue due to use of mtfprwz. Apparently mtfprwz is a ISA 2.07B/POWER8 instruction. My question is, how do I tell GCC to use a different ISA than I am using? I need a solution for compielrs found in the field, and that includes GCC 4.8: Jeff
