How to disable AMX but use AVX512_BF16 for bfloat16 GEMM on a cpu with AMX？

[Junwen-Zhang]

Hello, I want to test the performance of openblas using AVX512 instructions for bfloat16 GEMM, but openblas automatically calls AMX implementation. I would like to ask how to disable AMX on a CPU with AMX?

[martin-frbg]

try building for COOPERLAKE instead of SAPPHIRERAPIDS, or set OPENBLAS_CORETYPE=COOPERLAKE if you are using a DYNAMIC_ARCH build

[Junwen-Zhang]

Thank you for your reply! I compiled OpenBLAS according to your suggestion using "make PREFIX=/home/zjw/OpenBLAS-avx NO_LAPACK=1 USE_OPENMP=1 OPENBLAS_CORETYPE=COOPERLAKE DYNAMIC_ARCH=1 -j32 LIBPREFIX="libopenblas"", but it seems that I cannot run the gemm of bfloat16 type. The error message is "undefined reference to `cblas_sbgemm'". My CPU is Intel(R) Xeon(R) Gold 6430, which has the CPU flags of amx_bf16 and avx512_bf16. What can I do?