Vol. 3B 17-19

DEBUG, BRANCH PROFILE, TSC, AND RESOURCE MONITORING FEATURES

Figures 17-6 shows the structure of a 12-byte branch record in the BTS buffer. The fields in each record are as 
follows:

•

Last branch from — Linear address of the instruction from which the branch, interrupt, or exception was 
taken.

•

Last branch to — Linear address of the branch target or the first instruction in the interrupt or exception 
service routine.

•

Branch predicted — Bit 4 of field indicates whether the branch that was taken was predicted (set) or not 
predicted (clear).

Figure 17-5.  DS Save Area

Figure 17-6.  32-bit Branch Trace Record Format

BTS Buffer Base

BTS Index

BTS Absolute 

BTS Interrupt 

PEBS Absolute

PEBS Interrupt

PEBS 

Maximum

Maximum

Threshold

PEBS Index

PEBS Buffer Base

Threshold

Counter Reset

Reserved

0H

4H

8H

CH

10H

14H

18H

1CH

20H

24H

30H

Branch Record 0

Branch Record 1

Branch Record n

PEBS Record 0

PEBS Record 1

PEBS Record n

BTS Buffer

PEBS Buffer

DS Buffer Management Area

IA32_DS_AREA MSR

Last Branch From

Last Branch To

Branch Predicted

0H

4H

8H

0

31

4