Global static scheduling for Mixed Criticality (MC) systems demonstrates excellent results in terms of acceptance ratio and number of preemptions. But, no practical implementation and empirical evaluation have been presented yet for multi-processors systems. Moreover, the new kernel mechanisms it would require have not been studied. In this paper, we present two contributions on the implementation of global static schedulers For MC systems: G-RES, a global table-driven reservations LITMUS RT plugin, and G-MCRES, another LITMUS RT plugin scheduling MC tasks with global table-driven reservations and enforcing safe criticality mode changes. These contributions aim to solve the problems of instantaneous migrations and simultaneous mode changes in the context of global static schedulers. We based our experiments on scheduling tables generated off-line by GMH-MC-DAG, a meta-heuristic to schedule multiprocessor systems composed of multi-periodic Directed Acyclic Graphs of Mixed Criticality tasks with multiple criticality levels. The performances are very good w.r.t those of LITMUS RT and consistent with our temporal complexity evaluations.