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

Table Of Contents
B-152 Vol. 3
MODEL-SPECIFIC REGISTERS (MSRS)
12 Precise Event Based Sampling Unavailable. (RO)
1 = Processor does not support precise event-
based sampling (PEBS);
0 = PEBS is supported.
The Pentium M processor does not support PEBS.
15:13 Reserved.
16 Enhanced Intel SpeedStep Technology Enable.
(R/W)
1 = Enhanced Intel SpeedStep Technology
enabled.
On the Pentium M processor, this bit may be
configured to be read-only.
22:17 Reserved.
23 xTPR Message Disable. (R/W)
When set to 1, xTPR messages are disabled. xTPR
messages are optional messages that allow the
processor to inform the chipset of its priority. The
default is processor specific.
63:24 Reserved.
1C9H 457 MSR_LASTBRANCH_TOS Last Branch Record Stack TOS. (R)
Contains an index (bits 0-3) that points to the MSR
containing the most recent branch record. See also:
MSR_LASTBRANCH_0 (at 40H)
Section 18.9, “Last Branch, Interrupt, and
Exception Recording (Pentium M Processors)”
1D9H 473 MSR_DEBUGCTLB Debug Control. (R/W)
Controls how several debug features are used. Bit
definitions are discussed in the referenced section.
See Section 18.9, “Last Branch, Interrupt, and
Exception Recording (Pentium M Processors).
Table B-10. MSRs in Pentium M Processors (Contd.)
Register
Address
Register Name Bit Description
Hex Dec