Questions tagged [kernel]

Everything about Unix kernels: development, configuration, compilation, design, etc.

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How can PREEMPT_RT be used to provide real-time access to programs?

I have installed the real-time kernel 5.4.19-rt10 with the PREEMPT_RT patch on my Ubuntu 18.04. Now I need to write some programs that use the socket interface, how do I increase the preemption ...
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do i have less packages available on Gentoo or LFS [closed]

I am currently using arch linux. i am thinking about moving to gentoo or lfs but i am not sure. i feel like the application available on this distros are limited and there isn't much guides comparing ...
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two modules for WM8962

As can be seen on https://www.kernelconfig.io/search?q=wm8962&kernelversion=4.19.165&arch=arm64 there are seemingly two different kernel modules for the audio codec WM8962 and they have ...
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What changed from Linux Kernel 5.9 to 5.10?

I use a Measurement Computing DAQ in Ubuntu to perform continuous analog reads and writes from another system connected to the board. I have been using Ubuntu 16.04 (which went up to Linux kernel 4.15)...
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how to identify DIMM card problem from kernel messages

we have RHEL 7 server , and from dmesg log we can see the following details [13901018.980859] {9}[Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 4 [13901018.980868] {9}[...
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How to determine cause of poor CPU performance - AMD 75F3?

I have 2 identical machines with pretty identical configurations, however one machine is performing much worse than the other. After some digging it appears the CPUs on one machine is simply slower ...
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Can the Linux base images for Docker containers be used in environments other than Docker?

Containers share the machine’s OS system kernel https://www.docker.com/resources/what-container/ If container's share the machine's OS system kernel, is it true that there isn't a kernel included in ...
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Regolith 1.6 (21.04) / Ubuntu 21.04 is taking too long to boot

Dual booting Regolith 1.6 and Windows 11 on separate drives (windows ssd / regolith hdd). The total boot time from GRUB to entering the password is about 1m40s which seems a little high even for a HDD....
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Debian 10 kernel header package version mismatch

I install linux-headers-4.19.0-16-amd64 on Debian 10 running the kernel from package linux-image-4.19.0-16-amd64. I try to build WANPIPE driver from Sangoma and find in /lib/modules/4.19.0-16-amd64/...
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Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode) blutooth dongle doesn't work in Lubuntu with 5.13.0-40-generic kernel

Not only in this Linux version I tested with different Linux distro(s) the Bluetooth dongle from Cambridge Silicon Radio doesn't seem to work at all. I have seen some posts saying it was a problem up ...
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Present symbols in /proc/kallsyms with enabled KALLSYMS_ALL

If KALLSYMS_ALL is enabled on the kernel, are all the kernel symbols present in /proc/kallsyms? Or are there still some that aren't visible in it?
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Reparenting a process

I create a Linux Kernel Module and I try to find a way to re-parent a given process or change a given process PID. Is there any way of doing that? I found the following link but I could not make it ...
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Bondig two NIC slow upload

I have two NIC in pc/nas: eth0 (integrated motherboard): Settings for eth0: Supported ports: [ TP MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/...
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How to switch Void Linux to "linux-lts" kernel?

I already installed the "linux-lts" and "linux-lts-headers" but can't see it as an option to pick up in Grub login screen. Yes I've visited the page: https://docs.voidlinux.org/...
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How to downgrade the kernel in Alpine Linux (in Docker)?

I'm looking to test a DirtyPipe PoC and I need a vulnerable kernel version (5.8-5.15) to test on. I'm running an Alpine container in Docker for this purpose however am open to other Linux distros (...
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KASAN config in 32 bits architecture?

I am trying to compile linux kernel (version 4.4) with KASAN support on a 32 bits machine, but i can't enable it. It seems that it depends on 64 bits architecture only. So my question is about the ...
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what's root cause of "A start job is running for Create Volatile Files and Directories"

Stuck at "A start job is running for Create Volatile Files and Directories" after reboot a server(Debian 9.5, 64bit), and solve by this "boot-stuck-at-a-start-job-is-running-for-create-...
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Kernel Panic, how can I fix this?

I changed a setting in GRUB to fix a docker issue, next thing I know I reset my server, and here comes a week of headache. I thought I could post my question in here and get any help. Thank you!
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How to build the kernel correctly on its tinyconfig configuration?

I have A68N-5600E motherboard. Through the Live Linux image, I got a list of downloaded modules for this PC. amdgpu gpu_sched joydev radeon i2c_algo_bit drm_kms_helper ahci crct10dif_pclmul ...
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Open a terminal from an external device?

I'm currently learning about terminals, pseudo-terminals, etc. and I'm curious - today we all use the pseudo-terminals such as xterm or gnome-terminal that are part of the Linux GUI, and less often ...
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Where and how is the scheduler running? Can I "see" it? [duplicate]

The scheduler is not a thread but it's a kernel function, so there's no way to actually "see" what the scheduler is doing (I assume). These particular kernel parts are kind of invisible from ...
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Tuning with latency_ns

I would like to test the effect of latency_ns parameter on the execution time of a program. The program is a 16-thread MM implementation and the CPU is Ryzen with 8/16 (cores/threads). I also have ...
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Where is the process scheduler running? Can I track it?

Is the process scheduler "visible" at user space? Can I see it with ps? Maybe is it one of the kernel threads? If yes, how is it called? How can I "see" it? It doesn’t exist as a ...
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get all the files to be compiled from .config file

I have an old kernel and I didn't manage to get the toolchain to cross compile it. So I decided to upgrade this version of the kernel. My question is how can I know all the files(source, blobs and ...
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How to increase Size of /dev/sda1 in kali linux installed in Virtual Box

fdisk -l Disk /dev/sda: 80 GiB, 85899345920 bytes, 167772160 sectors Disk model: VBOX HARDDISK Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (...
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Out of memory on "Loading initial ramdisk" after kernel upgrade (4.15 to 4.19) on Ubuntu 18

I'm trying to upgrade my kernel to 4.19, because I need to run some benchmarks that require it (with some kernel options turned on). I'm completely stuck as to why this isn't working. I did two ubuntu ...
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Does writing a newline character into a sysctl (/proc/sys) file have any effect?

Today I ran into some code that's writing a newline character explicitly into a sysctl file. See moby/docker source code. My first thought is that the author has diligently copied the shell's ...
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1 answer
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Occasional stuck at boot-up line "Waiting for /dev to be fully populated"

On Linux Kernel 3 boot-up occasionally gets stuck at line: Waiting for /dev to be fully populated... Prior to that line I can see USB device enumeration errors: usb 2-1.2.3: device descriptor read/64,...
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How to change the default kernel in GRUB

I tried to change my grub file to select kernel 5.14.21, which is the 2nd one in the list: GRUB_DEFAULT=1 GRUB_TIMEOUT_STYLE=hidden GRUB_TIMEOUT=0 GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null ||...
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Incorrect operation of Linux (built in Buildroot) after startup X11

Built a Linux image in Buildroot 2022.02. After loading on real hardware, there is no mouse cursor display. The mouse itself is working (lit), but no visible actions occur after clicking on it. The ...
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initrd /casper/initrd: verbose output

In my previous question: grub2: error: can't allocate initrd - chainload an NTFS partition from FAT32 without errors on initial ramdisk (initrd) file I posted the error output: error: can't ...
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Patch 2nd Linux kernel: "module is in use"

how to patch kernel with a DKMS module if the module is 'in use'? The Kernel which should be used to get patched is not the one which is actual running on this machine. (uname -r) It is about hpsa ...
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Kernel option hidden even if the depending options are met

I am configuring a kernel (4.19.235) and need the option NO_HZ_FULL to be active. Currently, I only see the option HZ_PERIODIC and NO_HZ_IDLE in menuconfig. I checked the line "Depends on:" ...
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linux scsi: Unit Not Ready, Sense Key, Hardware Error

I have attached a USB device which is an enclosure for an NVMe M.2 storage unit. Both devices, the enclosure and the media, had been known to be in working order during their last use. When I connect ...
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Debugging both kernel and userland with QEMU and gdb

I am trying to debug the kernel in order to observe all the mechanisms such as context switching or interrupts handling. When I attach r2 or gdb with QEMU, it works well for the kernel part, but it ...
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How is the execution state saved at context switch in x86-64 linux kernel?

Since the TSS does not store the values of the registers in x86-64, how are those saved when the context switch occurs?
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Does Linux keep the memory on the same physical location?

Assuming the Linux kernel doesn't swap out my process's memory pages, can I assume their physical location in RAM will not be changed, or is it possible the kernel will move them around? The reason I'...
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/tools/build/Build.include: No such file or directory while compiling

I am trying to compile kernel module 4.18.0-240.el8.x86_64. On running make prepare getting the following error DESCEND objtool /usr/src/kernels/4.18.0-240.el8.x86_64/tools/build/Makefile.build:37: ...
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openSUSE - Many cannot determine ksym provides errors when packaging vanilla Kernel (git tag v5.17)

I am trying to build a RPM package for openSUSE Leap 15.2, because I need some special drivers, which are not implemented (or not back-ported) to Kernel v5.3. Cloned the GitHub repository from Linus ...
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Where are the kernel arguments documented?

I want to read more about the Linux Kernel argument for memtest. Where can I find out more information about the arguments my kernel accepts?
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Minor kernels updates applicability for people running custom kernel builds

Imagine the situation. You're running a custom kernel which you compiled from the vanilla sources using your own .config. A new minor update gets released, let's say 5.16.16 which was released just ...
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What is the best way to back-up the Linux kernel before performing a kernel and device tree update?

Is this as simple as duplicating the directory /boot to /boot~ before using dpkg to apply the updated Kernel ? So if the systems is bricked then all I would need to do is put the SD card into another ...
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How to update the kernel for a live CD Linux image

I have a liveCD ubuntu Linux iso image. I need to update the kernel of this image. I've tried to get the iso on a host Ubuntu system and move the compiled kernel and the modules from there to the ...
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Where is the signal handler located?

I know that the signal handler should usually run in userland. But I don't understand where is the handler code located. Is it inside the binaries?
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Issues updating dietpi?

I run only pihole on my pi zero w on dietpi. Noticed pihole wasnt blocking everything correctly (though some stuff still seems to be blocked) even though status shows everything is fine. So I updated ...
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Custom compiled kernel not showing updated changes

I have been following the How Tos/Custom_Kernel (I Need to Build a Custom Kernel) document at the CentOS Wiki to compile my kernel. I modified the kernel in ~/rpmbuild/BUILD/kernel-4.18.0-305.3.1....
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2 votes
1 answer
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Linux Kernel signature error after signing

OS: Ubuntu 20.04 Machine: Dell XPS 13 9370 Attempting to upgrade from Linux kernel 5.13.0 to 5.16.14. Have verified that kernel 5.16.14 runs properly without secure boot. Followed instructions here ...
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On Linux what is the technical minimum size for a functional swap partition

What is the technical minimum size for a functional (holds some pages) swap partition or file on Linux. If it's architecture dependent, or depends on the size of physical memory or something, how ...
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Verifying the running kernel matches the latest installed kernel in Ubuntu

unattended-upgrades in Ubuntu automatically installs security updates including the kernel but does not reboot automatically (and it's OK, I don't need/want automatic reboots). How can I find out ...
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Default Kernel Changing upon PC crash

Sometimes, my PC crashes. When it dose the kernel and configuration of ssh and vnc, all revert. The PC is running CentOS 7 (7.9.2009), and has a i9 11900K CPU. As i use this PC remotely as well as in ...
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