.. SPDX-License-Identifier: GPL-2.0+ .. index:: single: msr (command) msr command =========== Synopsis -------- :: msr read msr write Description ----------- The msr command reads and writes machine-status registers (MSRs) on x86 CPUs. The information is a 64-bit value split into two parts, for the top 32 bits and for the bottom 32 bits. The operation selects what information is read or written. msr read ~~~~~~~~ This reads an MSR and displays the value obtained. msr write ~~~~~~~~~ This writes a value to an MSR. Configuration ------------- The msr command is only available on x86. Return value ------------ The return value $? is 0 (true). Example ------- This shows reading msr 0x194 which is MSR_FLEX_RATIO on Intel CPUs:: => msr read 194 00000000 00011200 # Bits 16 (flex ratio enable) and 20 (lock) are set This shows adjusting the energy-performance bias on an Intel CPU:: => msr read 1b0 00000000 00000006 # 6 means 'normal' => msr write 1b0 0 f # change to power-save => msr read 1b0 00000000 0000000f