diff -rupN eigen-3.4.0/Eigen/src/Core/arch/AltiVec/MatrixProduct.h eigen-3.4.0-new/Eigen/src/Core/arch/AltiVec/MatrixProduct.h

--- eigen-3.4.0/Eigen/src/Core/arch/AltiVec/MatrixProduct.h	2021-08-18 22:41:58.000000000 +0200

+++ eigen-3.4.0-new/Eigen/src/Core/arch/AltiVec/MatrixProduct.h	2021-08-22 17:37:23.626427133 +0200

@@ -28,6 +28,9 @@

 #endif

 #endif

+#define EIGEN_ALTIVEC_DISABLE_MMA

+

+

 #ifdef __has_builtin

 #if __has_builtin(__builtin_mma_assemble_acc)

   #define ALTIVEC_MMA_SUPPORT

diff -rupN eigen-3.4.0/Eigen/src/Core/util/Macros.h eigen-3.4.0-new/Eigen/src/Core/util/Macros.h