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Questions tagged [msr]

MSR (Model-Specific Registers) are registers inside the CPU that provide direct access to advanced CPU features.

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Reading x86 MSR from kernel module

My main aim is to get the address values of the last 16 branches maintained by the LBR registers when a program crashes. I tried two ways till now - 1) msr-tools This allows me to read the msr values from the command line. I make system calls to it…
sg88
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Why does GS segment selector value does not change after SWAPGS instruction? (windows kernel debugging)

I'm trying to learn how the kernel works, during the process, using WinDbg, i have put a breakpoint at the Page Fault handler, after "swapgs" and "lfence" instructions: Page Fault Handler After I resume execution and WinDbg breaks, GS value stays…
yahel abraham
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How can I identify the MSR (microsoft reserved partition) on a disk with an MBR partition style layout?

If the disk has a gpt partition layout, the partition type guid will be E3C9E316-0B5C-4DB8-817D-F92DF00215AE according to https://en.wikipedia.org/wiki/GUID_Partition_Table But there's no room for information like that in an MBR partition table. I…
stu
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How to read the content of ID_AA64MMFR1_EL1 register into the 64-bit variable using inline assembly?

This is a follow-up question for this answer. I'm trying to read the content of ID_AA64MMFR1_EL1 register into the 64-bit variable using inline assembly: #include #include #include int main(void) { uint64_t…
pmor
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How can I monitor the events that cause the frequency of Intel CPU and Graphis to reduce, such as "Package/Platform-Level Power Limiting PL1 Status"

I am not very familiar with Intel's architectures but I need to access the events that trigger Intel CPU and Graphis limited performace for my project (particularly reduced frequency). I tried to find something related in Intel® 64 and IA-32…
Jason
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Do any Intel RAPL measurements include the fan / cooling?

I am using Intel RAPL to measure energy usage of a system. On a motherboard, the fan is typically connected to the CPU for temperature control. Is the CPU fan / cooler typically powered by the CPU? That is, is the chain PSU -> CPU -> CPU fan? Or…
nicovank
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How to introduce an MSR in gem5 and integrate it with Linux kernel?

I am trying to evaluate performance of custom prefetching models for Intel x86 architecture for which I would like to set and read some MSR registers. We are using Gem5 and Linux 5.4.84 kernel on a TimingSimpleCPU. I have introduced the registers at…
Sarthak Rout
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How do I query SVID VR telemetry on Intel/Windows [C/C++]?

The tool "HwInfo" seems to query power consumption from SVID VR telemetry. I could not find any resources how they obtain this information. Some alternatives I've considered is using the MSR data to get power consumption, but the APIs to read msr is…
Pranav Udupa
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Is there a way to enable programmatically L1 L2 L3 caches using msr-tools on Linux?

We have a server with Intel(R) Xeon(R) Gold 6338N CPU @ 2.20GHz. For this server the L1, L2, L3 caches seem not enabled... Is there a way to check the CPU registers with msr tools (rdmsr/wrmsr) on Linux to see if the caches are enabled and…
fstrati70
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How can I retrieve all commits that changed files with one or two kinds of extensions?

How can I retrieve all commits that changed files with one or two kinds of extensions, e.g. ".YAML" and ".JSON"?
Jimmy Zhao
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How to search Git commit messages with regular expression and output those messages & their line number to a text file

How to search Git commit messages (not diffs) in a software repository with regular expression and output those messages & their line number to a text file?
Jimmy Zhao
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No option to disable prefetching in BIOS

I have been trying to disable prefetching in my laptop. After many attempts, I realized intel stopped disclosing information on how to disable prefetching from nehalem architecture. Even if I try to modify the MSR, it always gives an error saying…
Saideepak Bejawada
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How can I verify that my hardware prefetcher is disabled

I have disabled hardware prefetching using the following guidelines: Installed msr-tools 1.3 wrmsr -a 0x1A4 1 The prefetcher information for my system (Broadwell) is in the msr address 0x1A4 as shown by intel documentation. I did rdmsr -a 0x1A4 …
Sabster
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How to detect if model specific register exist

I am trying to check if a bit is clear in IA32_VMX_EPT_VPID_CAP (48CH) but in some cases I am working with hardware that dose not have that msr(q9300) itself and I get segfault. I was wondering if there was an instruction or a "nice" way to check if…
dmg
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What is the MSR differences between AMD x86 and Intel x86?

I know both the AMD and Intel implement the x86 architecture CPU, both of them contains the MSR registers. I am not sure if the MSR registers in both implementation are the same. If not, what is the main differences? Thanks!
Dahui
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