counters. These counters do not exist on all CPUs, but where they
do exist, can be used for counting events such as dcache misses that
would otherwise be difficult or impossible to instrument by code
inspection or hardware simulation.
pmc(9) is meant to be a general interface. Initially, the Intel XScale
counters are the only ones supported.
broke too many assumptions makde by other parts of the source tree,
and the strategy and how it was supposed to work was never discussed
on tech-userlevel, nor was it applied consistently (to all ARM ports
and to other ports which have common MACHINE_ARCH code, such as MIPS,
m68k, powerpc).
Verified to complete a full "make build" on cats, dnard, evbarm,
and netwinder.
