  We construct necessary and sufficient geometric conditions for a class of
AdS$_2$ solutions of M-theory with, at least, minimal supersymmetry to exist.
We generalize previous results in the literature for ${\cal N}=(2,0)$
supersymmetry in AdS$_2$ to ${\cal N}=(1,0)$. When the solution can be locally
described as AdS$_2\times \Sigma_g \times \,$SE$_7$ with $\Sigma_g$ a Riemann
surface of genus $g$ and SE$_7$ a seven-dimensional Sasaki-Einstein manifold,
we clarify and unify various solutions present in the literature. In the case
of SE$_7=Q^{1,1,1}$ we find a new solution with baryonic and mesonic charges
turned on simultaneously.
