Questions tagged [linux-kernel]

Questions about Linux kernel and Linux kernel related topics eg. implementation details such as system calls, kernel customization, etc. For Linux user space topics which do not involve kernel details, [linux] or distribution tag are more suitable.

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dentry/inode caching on multi-cpu machines / memory allocator configuration

While doing performance benchmarking on CPLEX, I ran across a strange issue. The details are posted in a blog: https://community.ibm.com/community/user/ai-datascience/blogs/xavier-nodet1/2021/07/08/...
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Convention of using #includes for the header files for using a system call provided by linux kernel into my custom system call

I am trying to design a system call of my own. And as per need, I am considering using a system call already provided by linux kernel. Below is the program : #include <linux/kernel.h> #include &...
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how to exclude not important kernel messages that hide the real kernel messages lines

we have HP HW ( DL 380 G10 ) physical REDHAT machines. ( version 7.5 ) and as we can see the kernel messages are filled by the following messages about. ACPI Error: Method parse/execution failed [\...
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Set affinity of a process using TASKSET or sched_setaffinity() to a processor core isolated using CPUSET

First, let me give a background of what I am trying to achieve. I know how to isolate a particular CPU using boot param (isolcpu and nohz_full; the housekeeping subsystem setup). But as per my ...
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Failed to start network manager wait online stuck not booting kali Linux

Can anyone help I'm getting this error failed to start network manager wait online but don't boot up I have posted the error message picture
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1 answer
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Does "TUNED_BOOT_CMDLINE" /etc/tuned/bootcmdline overwrite BOOT_IMAGE of /proc/cmdline?

TuneD tool provides an option to configure kernel command line via TUNED_BOOT_CMDLINE variable of the /etc/tuned/bootcmdline, which is not done directly but via setting a desired TuneD performance ...
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How to read TCP congestion control parameters on Linux?

How do I read TCPs congestion control parameters on Linux in realtime for a connection? Specifically, I'm interested in the cwnd (congestion control window) and ssthresh (slow start treshold) in ...
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Set low latency kernel as default in Lubuntu

I have Lubuntu and have installed the low-latency kernel. After the booting the kernel used is still the old generic kernel. How can I set the low-latency kernel to be used by default (instead of ...
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Asahi Linux file /boot/grub/arm64-efi/normal.mod file not found

I am trying to install Asahi Linux on my M1 mac, and it doesn't work during the U-boot stage. It says ** Unable to read file / ** Failed to load '/' BootOrder not defined EFI boot manager: Cannot load ...
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rcu_sched vs rcu_preempt CPU stalls

I have basic query regarding the RCU CPU stalls, sometimes there is message like INFO: rcu_sched self-detected stall on CPU, and sometimes it's INFO: rcu_preempt detected stall on CPUs/task, what is ...
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"reset SuperSpeed USB device number 1 using xhci_hcd" kernel log message

When steadily reading data off a connected via USB3 HDD drive (cat /dev/sdx > /dev/null) in a VirtualBox VM (Host: Fedora 37, guest: doesn't matter) I see a constant stream of kernel messages ...
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Linux internals [closed]

I really want to learn linux internals This Linux Kernel Internals and Development (LFD420) looks promising but its super $$. I googled a lot but all info. seem scattered. Please tell me where to ...
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Fast wideblock AES disk encryption in Linux?

I recently learned that Linux supports Adiantum as a disk encryption cipher (run cryptsetup benchmark -c xchacha20,aes-adiantum-plain64 to try it out on your system). While Adiantum is primarily meant ...
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How does linux prevent whole system from freezing when a process crashes

I know about how the kernel slices the CPU time to its processes, but how does it actually hand over control and take it back and what happens to taking control back when the process crashes?
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How to solve this undefined issue in the kernel source?

Basically, I was trying to add the RTL8821Au driver into the kernel but while compilation I'm facing this undefined issue. How we can solve this issue? drivers/net/wireless/rtl8821cu/core/rtw_p2p.o: ...
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How to run linux distributions on android tablets?

I heard that android uses a linux kernel. Does that mean android tablets can run linux distributions like debian or arch? How can I replace stock android with linux on a tablet?
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Recompiling a Kernel module from source

Good night, I am trying to recompile a kernel module from its source (in case you are wondering, it is the b43 driver module) on Debian 11. I've ran into a problem, which is that I want to specify ...
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How to limit which characters are allowed in filenames?

Following up on Fixing Unix/Linux/POSIX Filenames: Control Characters (such as Newline), Leading Dashes, and Other Problems*, is there some way to forbid the creation of files with problematic names ...
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Improve Linux kernel compile time by disabling specific modules

I have to compile the Linux kernel quite frequently for a device with a limited use-case. Naturally, I don't need most of the modules of the Linux kernel. Is there a good way to determine which ...
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What's inside Linux kernel sysfs holders directory?

What exactly is under the /sys/module/<module_name>/holders directory? From what I see it's all symlinks. But symlinks representing what?
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RP PIO loge size 0 is invalid - Upgrade kernel?

Update I ended up re-installing since I was stuck in emergency > mode it would be faster. After install installed the 6.1 kernel from the vanilla repo. After this I added the nvidia drivers (525.60....
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1 answer
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What exactly differentiates operating system from kernel? [closed]

Ok, so kernel is part of operating system. So therefore, it should be correct to say that: operating system = kernel + X So what is this "X"? What components should you add to kernel so that ...
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Force a PCI device to be issued a specific I/O port range

I am trying to port a driver to Linux, but the device doesn't respond to commands issued to it's I/O port range under Linux. It responds correctly under windows, which assigns it a different port ...
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kernel upgrade from 5.10.0-16-amd64 to 5.10.0-18-amd64 debian 11 bullseye

i'm trying to upgrade from kernel version 5.10.0-16-amd64 to kernel version 5.10.0-18-amd64 but can't seem to find the tar or the .sig files, any ideas where to find them to download?
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Compress Linux Kernel with xz

Just out of curiosity, is it possible to compress the Linux kernel with xz, and if so, how would I go about this? I actually tried compressing a raw kernel image with xz [a silly idea] and loading it ...
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What type of queue is TCP accept queue in Linux -- FIFO/LIFO/other?

I am wondering if TCP accept queue in Linux is a FIFO or LIFO, or any other type of queue? Asking the same from another perspective: does accept() yield connections in the same order as they arrived ...
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How to configure two ethernets eth0 and eth1 in debian 11?

I want to configure both eth0 and eth1 in debian 11.6 currently, I have configured it as follows # The loopback network interface auto lo iface lo inet loopback # The primary network interface allow-...
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Why does setting the vm.watermark_scale_factor property increase ram consumption?

When I configure the vm.watermark_scale_factor property in /etc/sysctl.conf which is the property in charge of indicating to the kernel when the kswapd daemon starts to activate for paging from ram to ...
25 votes
1 answer
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How does the kernel know it's resuming from hibernation, not booting?

When a Linux system hibernates and resumes from hibernation, I think that the kernel needs to know that it's resuming, not booting. Otherwise, the kernel will start the usual boot process, and will ...
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Debian kernel version and its package version mismatch

I'm trying to install the latest available kernel from bullseye-backports: ceremcem@erik3:~$ sudo apt install -t bullseye-backports linux-image-amd64 btrfs-progs linux-headers-amd64 Reading package ...
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How to stop "rsyslogd" and "systemd-journal" high cpu usage in debian 11 minimal?

I'm running Debian 11 minimal I observed that rsyslogd & systemd-journal are taking 100% of cpu usage what will be the reason and how to stop the same? 1599 root 20 0 54128 24832 2396 ...
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Error: vmaster hook already present before cdev!

The question I would like to know how to prevent the following error to appear at my log: snd_hda_codec_conexant hdaudioC0D0: vmaster hook already present before cdev! From the code I presume that it ...
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kernel function for the calculation of timeslice by CFS in Linux

I am looking for the kernel function/code that is used by CFS to calculate timeslice for any task that is going to run. I have seen many answers regarding the concept/formula for it, but I want to ...
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1 answer
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Is there a downside to a signed kernel?

Mostly a general linux question, but where it needs to be specific I am referencing Debian 12 Bookworm amd64 UEFI booting through grub(not direct kernel stub). I have secure boot disabled in firmware ...
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Restore original interrupt handler in linux

I removed the existing interrupt handler for the keyboard and registered my interrupt handler and after removing my interrupt handler, I want to restore the original interrupt handler for the keyboard....
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How to name a device in the device tree?

I have used a device tree overlay file (dtbo) to add a hardware reference over the i2c-2 node to my device tree. This device is an accelerometer that implements an existing driver that can be found ...
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1 answer
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How to implement i2c device in Device Tree?

I currently attempting to implement the mma8452 driver for my mma8451Q accelerometer by adding it to the the Linux Device Tree. Currently I am taking the route of creating a device tree overlay file (...
2 votes
1 answer
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How to connect 2 VMware instance running on same Linux host machine via emulated ethernet cable (accessible via mac address)?

I have a host machine running Linux (ubuntu-18.04). There I have 2 VMware instances configured and the network is configured via NAT. I can ping from VM1 to VM2 (and vice-versa) via their local IPs ...
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What does this backtrace mean in dmesg

While running many short period threads for long time, I'm ended up with the crash. And it didn't produce coredump too. Can anybody give some insights on the below logging in dmesg. Nov 29 19:02:34 (...
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Some functions are declared with prototype but can not find definition in Linux

I am a newbie to Linux operating system and recently I was digging on the implementation details of uprobe. I encountered a macros vma_interval_tree_foreach which I searched it on https://elixir....
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how does linux kernel choose the right src ip when route packet?

I have a kubernetes cluster using Calico as CNI plugin. We can get some routes in my local route table like root@k8s-master:~# ip r default via 192.168.100.1 dev ens18 proto dhcp src 192.168.100.215 ...
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How does anti-cheat work and how is it distributed on Steam Games?

According to Levvvel's list of kernel-level anti-cheat games, many modern games use kernel-level anti cheat. One provider of kernel-level anti-cheat is Epic with Easy Anti-Cheat and one game using ...
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How to work with network and hard disk in kernel.c?

I am building a small operating system I'm going to save the information on the hard disk, like creating a txt file on the hard disk And also performing network tasks such as socket or http requests ...
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I need help building a kernel

I have some TS-7600 single board computers and I want to recompile the linux kernel to version 3.14 where I will gain some easy of use for the hardware clock, and compatible devices. There is a ...
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Extract and repack miner firmware

i would like to know how to extract a miner firmware and translate the www folder and change logo, file command return : gzip compressed data, was "blah3.tar", last modified: Mon Jan 15 04:...
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Change NVIDIA device files via modprobe.d: NVreg_DeviceFileGID not changed

I want to change NVIDIA device files. have # nvidia-smi -L GPU 0: Tesla V100-PCIE-32GB GPU 1: Tesla V100-PCIE-32GB # cat /proc/driver/nvidia/version NVRM version: NVIDIA UNIX x86_64 Kernel Module ...
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Install arch with linux-lts

I wanted to install Arch with LTS kernel so I changed the line # pacstrap -K /mnt base linux linux-firmware with # pacstrap -K /mnt base linux-lts linux-firmware but then I got some errors and my ...
9 votes
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Why do processes on Linux crash if they use a lot of memory, yet still less than the amount of swap space available?

I am using Linux 5.15 with Ubuntu 22.04. I have a process that uses a lot of memory. It requires more memory than I have RAM in my machine. The first time that I ran it, it was killed by the OOM ...
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Where can I find the device tree source include (.dtsi) files?

I am attempting to review my device tree to learn more about how the usb endpoints are defined, and also just to learn more about device trees. I am currently using a BeagleBone Black image, and I ...
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ubuntu packages hold command

I'm using Ubuntu 20.04.03 - server and I would like to hold upgrades for specific ubuntu packages, it means that apt update & upgrade commands would not affect the specific packages that I would ...
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