The 2nd patch (RFC for now) is meant to address a regression reported on the list under "Problems with APIC on versions 4.9 and later (4.8 works)". In the course of analyzing output from a debugging patch I ran into another anomaly again, which I thought I should finally try to address. Hence patch 1.
1: change initiation of the calibration timer 2: don't move TSC backwards in time_calibration_tsc_rendezvous() Jan
