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

Table Of Contents
Vol. 3 B-163
MODEL-SPECIFIC REGISTERS (MSRS)
187H 391 PerfEvtSel1 (EVNTSEL1)
7:0 Event Select.
Refer to Performance Counter section for a list of
event encodings.
15:8 UMASK (Unit Mask).
Unit mask register set to 0 to enable all count
options.
16 USER.
Controls the counting of events at Privilege levels
of 1, 2, and 3.
17 OS.
Controls the counting of events at Privilege level
of 0
18 E.
Occurrence/Duration Mode Select
1 = Occurrence
0 = Duration
19 PC.
Enabled the signaling of performance counter
overflow via BP0 pin.
20 INT.
Enables the signaling of counter overflow via input
to APIC
1 = Enable
0 = Disable
23 INV.
Inverts the result of the CMASK condition
1 = Inverted
0 = Non-Inverted
31:24 CMASK (Counter Mask).
1D9H 473 DEBUGCTLMSR
0 Enable/Disable Last Branch Records
1 Branch Trap Flag
Table B-11. MSRs in the P6 Family Processors (Contd.)
Register
Address
Register Name Bit Description
Hex Dec