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