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This provides the architecture-specific functions needed to access PMU hardware on the 64-bit PowerPC processors. It has been designed for the IBM POWER family (POWER 4/4+/5/5+/6 and PPC970) but will hopefully also suit other 64-bit PowerPC machines (although probably not Cell given how different it is in this area). This doesn't include back-ends for any specific processors. This implements a system which allows back-ends to express the constraints that their hardware has on what events can be counted simultaneously. The constraints are expressed as a 64-bit mask + 64-bit value for each event, and the encoding is capable of expressing the constraints arising from having a set of multiplexers feeding an event bus, with some events being available through multiple multiplexer settings, such as we get on POWER4 and PPC970. Furthermore, the back-end can supply alternative event codes for each event, and the constraint checking code will try all possible combinations of alternative event codes to try to find a combination that will fit. Signed-off-by: Paul Mackerras <paulus@samba.org>