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On Tue, Sep 5, 2017 at 10:28 PM, Grant <emailgrant@×××××.com> wrote: |
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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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