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Vol. 3 16-35
DEBUGGING, PROFILING BRANCHES AND TIME-STAMP COUNTER
Processors based on Intel microarchitecture (Nehalem) have an LBR MSR Stack as
shown in Table 16-8.
Table 16-8. LBR Stack Size and TOS Pointer Range
16.6.2 Filtering of Last Branch Records
MSR_LBR_SELECT is cleared to zero at RESET, and LBR filtering is disabled, i.e. all
branches will be captured. MSR_LBR_SELECT provides bit fields to specify the condi-
tions of subsets of branches that will not be captured in the LBR. The layout of
MSR_LBR_SELECT is shown in Table 16-9.
Table 16-6. IA32_LASTBRACH_x_FROM_IP
Bit Field Bit Offset Access Description
Data 47:0 R/O The linear address of the branch instruction itself,
This is the “branch from“ address
SIGN_EXt 62:48 R/0 Signed extension of bit 47 of this register
MISPRED 63 R/O When set, indicates the branch was predicted;
otherwise, the branch was mispredicted.
Table 16-7. IA32_LASTBRACH_x_TO_IP
Bit Field Bit Offset Access Description
Data 47:0 R/O The linear address of the target of the branch
instruction itself, This is the “branch to“ address
SIGN_EXt 63:48 R/0 Signed extension of bit 47 of this register
DisplayFamily_DisplayModel Size of LBR Stack Range of TOS Pointer
06_1AH 16 0 to 15
Table 16-9. MSR_LBR_SELECT
Bit Field Bit Offset Access Description
CPL_EQ_0 0 R/W When set, do not capture branches occurring in ring 0
CPL_NEQ_0 1 R/W When set, do not capture branches occurring in ring
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