  The K\"ahler-Dirac fermion, recognized as an elegant geometric approach,
offers an alternative to traditional representations of relativistic fermions.
Recent studies have demonstrated that symmetric mass generation (SMG) can
precisely occur with two copies of K\"ahler-Dirac fermions across any spacetime
dimensions. This conclusion stems from the study of anomaly cancellation within
the fermion system. Our research provides an alternative understanding of this
phenomenon from a condensed matter perspective, by associating the interacting
K\"ahler-Dirac fermion with the boundary of bosonic symmetry-protected
topological (SPT) phases. We show that the low-energy bosonic fluctuations in a
single copy of the K\"ahler-Dirac fermion can be mapped to the boundary modes
of a $\mathbb{Z}_2$-classified bosonic SPT state, protected by an inversion
symmetry universally across all dimensions. This implies that two copies of
K\"ahler-Dirac fermions can always undergo SMG through interactions mediated by
these bosonic modes. This picture aids in systematically designing SMG
interactions for K\"ahler-Dirac fermions in any dimension. We present the exact
lattice Hamiltonian of these interactions and validate their efficacy in
driving SMG.
