Typically the non-empty feasible space of a SDP has some curved regionboundary which is why the feasible space has infinitely many extreme points. Is it ever possible to have a SDP whose non-empty feasible region is the convex hull of a finite (exponential) number of rank-$1$ matrices? If yes, how do we characterize such a SDP? What can we say about the affine hull of these extreme points? Is it somehow related to the affine space defined by the set of equality linear constraints?