  The goal of this paper is to study global dynamics of $C^\infty$-smooth
slow-fast systems on the $2$-torus of class $C^\infty$ using geometric singular
perturbation theory and the notion of slow divergence integral. Given any
$m\in\mathbb{N}$ and two relatively prime integers $k$ and $l$, we show that
there exists a slow-fast system $Y_{\epsilon}$ on the $2$-torus that has a
$2m$-link of type $(k,l)$, i.e. a (disjoint finite) union of $2m$ slow-fast
limit cycles each of $(k,l)$-torus knot type, for all small $\epsilon>0$. The
$(k,l)$-torus knot turns around the $2$-torus $k$ times meridionally and $l$
times longitudinally. There are exactly $m$ repelling canard limit cycles and
$m$ attracting non-canard limit cycles.
