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…
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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…
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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…
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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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