On Tue, Sep 5, 2017 at 10:28 PM, Grant <[email protected]> wrote: >>>> Now I'm running into "trap invalid opcode" errors on the older >>>> systems. Can I disable some of the newer CPU instruction sets on the >>>> master laptop when compiling to hopefully generate binaries that will >>>> work on the older systems? >>> >>> Yes. You need to find out CPU_FLAGS_X86 and "-march=" values the >>> machines have, and use that in make.conf. Run the commands... >>> >>> cpuinfo2cpuflags-x86 >>> gcc -c -Q -march=native --help=target | grep march= >>> >>> ...on the target machines. This will tell you what "native" is and >>> what CPU_FLAGS_X86 values to use. >>> >>> https://gcc.gnu.org/onlinedocs/gcc-6.3.0/gcc/x86-Options.html#x86-Options >>> lists available "march=" options, and what instruction sets they support. >>> E.g. my old core2 desktop shows... >>> >>> [d531][waltdnes][~] cpuinfo2cpuflags-x86 >>> CPU_FLAGS_X86="mmx mmxext sse sse2 sse3 ssse3" >>> >>> [d531][waltdnes][~] gcc -c -Q -march=native --help=target | grep march= >>> -march= core2 >>> >>> >>> Unless the laptops are really old, you can probably get away with... >>> CFLAGS="-O2 march=core2 -mfpmath=sse -fopenmp -fomit-frame-pointer -pipe >>> -fno-unwind-tables -fno-asynchronous-unwind-tables" >>> >>> booby trap 1) Unless all machines are Intel "Atom" family, do *NOT* use >>> a "march=" that implements the "movbe" instruction. >>> >>> booby trap 2) If you throw in any AMD-based machines proceed with care. >>> >>> Can you post the output of... >>> gcc -c -Q -march=native --help=target | grep march= >>> ...for all the target machines? >> >> >> Let's see how -mtune=native goes and resort to the above if necessary. >> It doesn't look too bad though. > > > emerge -e world has finished and pushed and -mtune=native seems to > have solved the issue for now. >
You might be interested in "-march=x86-64 -mtune=generic" though this will mean you might miss out on some optimizations.
