USDT probes are advertised to kernel by initialization code with
atrribute((constructor))). It seems that on Solaris the .init-ish code
of the main object is executed before RD_PREINIT point is hit. On
FreeBSD that is not the case. And because on FreeBSD there is no other
well-defined point between RD_PREINIT and main() we have to parse a
DTrace script when main is hit, for time being.
A footnote: currently we actually post RD_POSTINIT event, but that's a
bug because the event is triggered by hitting r_debug_state which
happens before any init code is executed.
Reported by: markj
5d33cbbf9d