Intel 64 and IA-32 Architectures Software Developers Manual Volume 3B, System Programming Guide Part 2

Table Of Contents
18-96 Vol. 3
DEBUGGING AND PERFORMANCE MONITORING
FORCE_OVF flag, bit 25 — When set, forces a counter overflow on every
counter increment; when clear, overflow only occurs when the counter actually
overflows.
OVF_PMI flag, bit 26 — When set, causes a performance monitor interrupt
(PMI) to be generated when the counter overflows occurs; when clear, disables
PMI generation. Note that the PMI is generated on the next event count after the
counter has overflowed.
Cascade flag, bit 30 — When set, enables counting on one counter of a counter
pair when its alternate counter in the other the counter pair in the same counter
group overflows (see Section 18.18.2, “Performance Counters,” for further
details); when clear, disables cascading of counters.
OVF flag, bit 31 — Indicates that the counter has overflowed when set. This flag
is a sticky flag that must be explicitly cleared by software.
The CCCRs are initialized to all 0s on reset.
The events that an enabled performance counter actually counts are selected and
filtered by the following flags and fields in the ESCR and CCCR registers and in the
qualification order given:
1. The event select and event mask fields in the ESCR select a class of events to be
counted and one or more event types within the class, respectively.
Figure 18-37. Counter Configuration Control Register (CCCR)
63
32
Reserved
Reserved
Reserved: Must be set to 11B
Compare
Enable
31
24 23
20 19 16
15 12
11
0
1718
2526272930
Edge
FORCE_OVF
OVF_PMI
Threshold
Cascade
OVF
Complement
Reserved
13
ESCR
Select
Reserved