These utilities allow the inspection or modification of Model Specific Registers (“MSR”s).

Note: modifying the contents of an MSR can cause the processor or system to malfunction. Refer to the Intel 64 and IA-32 Architecture Software Developer’s Manual, document number 335592, or the appropriate AMD process family documentation for details of each MSR for each processor family.

Command line

msrutil.exe [-t cpunum] -all

msrutil.exe [-t cpunum|-tm cpumask] reg value [mask]

msrutil.exe [-t cpunum] reg [value [mask]]

rwmsr.rta -all

rwmsr.rta reg [value [mask]]

Available options

-t cpunum

access MSR on this core

-tm cpumask

write MSR on these cores

-v

verify a write by reading the register back

reg

MSR to read/write

value

64-bit value (hex) to write to MSR

mask

64-bit mask to AND with reg before OR-ing with value

Examples

1. To read a single MSR from a given CPU thread. Example: read MSR 10H from CPU thread 2
   msrutil -t 2 10
2. Write a value to an MSR on a given CPU thread:
   msrutil -t 1 c8f 100000000
3. Write a value to an MSR on multiple CPU threads defined by a bitmask. Example: write 0 to MSR 0E8H on CPU threads 0-4:
   msrutil -tm 1f e8 0