Questions tagged [kernel]

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

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Is there a system for live kernel upgrade from 5.4 to 5.10?

I have tested ksplice uptrack on Ubuntu 20.04 I see It applies patches to live kernel. For example: Effective kernel version is 5.4.0-139.156 uptrack-upgrade -y The following steps will be taken: ...
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Missing early boot logs before busybox-syslog starts up

I have syslog starting up about 5s into the boot sequence. I have a script that appends to /dev/kmesg that runs early in the boot seconds, before syslog starts up. I am not seeing those logs that went ...
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Linux Traffic Control (tc) not working without reboot

When trying to run tc qdisc add dev $INTERFACE root handle 1: prio priomap 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 tc qdisc add dev $INTERFACE parent 1:1 handle 10: netem loss "${LOSS}"% I ...
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List linux kernel and should I keep noly one

I'm running POP_OS 22.04 LTS, and I'm new to the Linux Kernel aspects. I want to give a shot to the low-latency kernels and while digging, I notice that I already have several versions installed. dpkg ...
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Force a specific device to be in suspend state

I'm working on a battery powered custom stm32mp2-based board. Several peripherals are present on this board (NFC, LCD, USB, ...). When the system is not interacting with a user it is switched to a ...
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init script to move file and reboot

I need a tiny init script which get arguments from /proc/cmdline and then move or copy dirs or files passed to in via /proc/cmdline and reboot. Everything is fine, except /sbin/reboot does not work ...
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Create custom bootable linux image; not a livecd

So I've compiled my kernel and initrd. How can I then create an image and install grub to actually load this image from a disk? My goal isn't to create a livecd out of it that is bootable from USB, as ...
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DKMS Modules Installation Error - Pop!_OS 22.04 LTS

I am getting the following error everytime I do $sudo apt upgrade The following packages have been kept back: libegl-mesa0 libgbm1 libgl1-mesa-dri libglapi-mesa libglx-mesa0 libgoa-backend-1.0-1 ...
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With Unified Kernel Images, how are custom initrd scenarios (such as multipath boot) addressed?

I was looking at the Fedora change set for 38 and saw this which seems like a neat idea but I was wondering how this affects systems that need custom files to be present in the initrd. One example is ...
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kernel parameters + what is the right way to refresh the kernel parameter from custom.conf after reboot

we set the following kernel parameters in file 99-custom.conf more /etc/sysctl.d/99-custom.conf net.ipv4.tcp_low_latency = 1 net.ipv4.tcp_adv_win_scale = 1 net.ipv4.tcp_max_syn_backlog = 30000 net....
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Should I update the linux firmware if I am not updating the kernel?

I am running Linux Mint 20.3 . Should I update the Linux Firmware that Update Manager is showing if I am not also updating the Kernel update offered? I hesitate to update the 5.4.0-42 Kernel because I ...
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Can not create video device file (/dev/videoX)

I use ov7670 sensor and zedboard (zynq 7000) to capture video. I using petalinux to custom OS for system. i was porting ov7670 driver for ov7670 sensor but video device file (/dev/videoX) isn't ...
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How to remove old kernel initramfs+vmlinuz in /boot (Archlinux)

When I re-install Archlinux, old kernels will leave initramfs and vmlinuz in /boot and exists in my grub config. But I do not install them so I cannot boot from them. I cannot delete them by sudo rm, ...
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How does the the linux kernel detect a usb device

I am facing an issue with an embedded Linux platform. There is a USB hub device which connects to the main CPU. However, this USB device intermittently is not detected on some power cycles. I am ...
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RHEL - keeping a specific kernel version, possible?

I was looking to keep a specific kernel version on my machine. To prevent it from being overridden or removed without having to grow or up the # of kernels the system keeps as my only solution as ...
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slab allocation for allocating memory to the kernel processes?

I'm reading about kernel memory allocation, and working of slab allocation. I've written my concept regarding this allocation process. and It will be tremendous help if i could get validation. this is ...
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What do these i915 errors mean in the Kernel log?

Currently my kernel log has these errors, i915: [drm] *ERROR* CPU pipe C FIFO underrun: transcoder, i915: [drm] *ERROR* [ENCODER:350:DDI TC3/PHY TC3][DPRX] Failed to enable link training i915: [drm] *...
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kernel name in grub menu vs kernel.conf

I'm trying to know the difference between changing something in the name of the kernel in the grub menu vs changing the content of the name of the kernel in the .conf file in the /boot/loader/entries. ...
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1 CPU core pinned at 100% with krunner according to htop; how to alleviate?

Currently having an issue on my virtualized and headless Linux server (Intel 8th Gen i5, Ubuntu 22.04 LTS, kernel 5.15.0-60-generic). My hypervisor is Proxmox if that helps. For some reason, one of my ...
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Why Linux kernel randomness is limited? [duplicate]

Why linux kernel has limited size of entropy. If you run cat /proc/sys/kernel/random/poolsize you get 4096. What is that "magic" number and why can't the randomness of the kernel increase ...
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Rfkill fails with cannot open nor read /dev/rfkill: no such file or directory and bad file descriptor

I was trying to activate the bluetooth service in my embedded system (google coral, Mendel Linux), that worked before. I encounter the following (it was not running before but I managed to fix with, ...
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New Ubuntu version on old device

I have an old device (tv box) with Android 4.4.2 (kernel 3.0.x), and I've found an old version of Ubuntu with some kernel that runs fine. But this old version is more outdated, and it is not usable. ...
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How to accept extra params in open syscall?

I am developing a filesystem module for linux as a project. I want the files to be protected passwords. I want that open() accepts a password in addition to the filepath and mode. But I cannot find ...
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How fix "No rule to make target 'arch/arm64/boot/dts/kona-rumi.dtb', needed by '__build'. Stop

Previously, I had the same error related to the file: arch/arm64/boot/dts/qcom/apq8016-sbc.dtb, but I solved it by deleting the line subdir-y += qcom from the arch/arm64/boot/dts/Makefile. Now a new ...
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Dummy interface is not reachable from other system through ping

I connected two Debian 10 systems with a direct link. On one of them I defined a dummy interface and on the other I gave a static route to access it. I see the traffic from the sender on the interface,...
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All memory consumed by nothing in Linux

I have a 8GB machine running Ubuntu 5.15 kernel. I only have 1GB of available memory even just after reboot. I tried free -m, cat /proc/meminfo and ps aux tricks to list the most memory consuming ...
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Debian 11 hangs while booting after kernel update to 5.10.0-21

Debian 11 hangs while booting after kernel update to 5.10.0-21. Interestingly, when I'm selecting previous kernel (5.10.0-20) everything works ok. Tried several times. Any idea? Cheers, Leszek
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Cannot dual boot into Ubuntu 18.04.6

I'm trying to dual boot into Ubuntu 18.04.6, but I get an error. 22.x works fine, but I need that version specifically. ... TPM_CRB ... : ACPI REGION DOES NOT COVER THE ENTIRE COMMAND/RESPONSE BUFFER ...
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unrecognized option '-EL'

I'm trying to build an android kernel. On every build I get a few errors: /usr/bin/as: unrecognized option '-EL' clang-16: error: assembler command failed with exit code 1 (use -v to see invocation) ...
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Dump kprint buffer after warm restart

I have the problem, that my Linux machine in some situations just stops and I have no clue what exactly is happening. It's when I run a certain software. It's an embedded ppc64 system, running the ...
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Convert Xorg log timestamps to human readable timestamps

I need to change the time stems of a whole Xorg/X11 log file (e.g. /var/log/Xorg.0.log) into human readable format. The default format is the time in seconds since boot, preferably yyyy-mm-dd + time. ...
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insmod command in not completed even after hours

I was trying to set up the MemLiner environment in the CloudLab. I was following the instructions from the GitHub page. When I try to connect the CPU server and memory server nodes in the "2.1 ...
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Internal webcamera with hi847 sensor doesn't work on alder lake

I have dualboot system with Windows 11 and Ubuntu 22.10. Notebook based on intel Alder Lake platform with i5 1230u processor. Internal WebCamera (HI847) sensor doesn't work in Ubuntu, but works in ...
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How to install a becachefs supporting kernel on Linux Mint 21 and LMDE5?

The first bcachefs from Kent Overstreet supporting Kernel 6.1, are released on 2022-12-11 by Linus Torvalds. See following sources: https://evilpiepirate.org/git/bcachefs.git https://web.archive.org/...
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How to integrate C program with init file?

So I am working on building minimal os using busybox. What I want is I want to run my .net program from BIOS. But I am not sure linux will run .net program or not, so to clear my path I am using C ...
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modules are missing /sys/module/*/parameters directories, how to enable them?

Many of my modules are missing /sys/module/*/parameters directory and I can't check the module loaded parameters. # printf "%s\n" /sys/module/*/parameters | wc -l 125 # lsmod | wc -l 151 # ...
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My Fan Pc Spinning fast after updating linux kernel?

I tried updating from linux kernel 5.19 to 6.1.9 My laptop fan is usually not active when there are no applications, even when opening many applications, unless I do something heavy, but after I ...
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Does ftrace have a function similar to trace_printk() which can print out the current function's call stack?

TLDR; Does ftrace have a function similar to trace_printk() which can print out the current function's call stack? I know how to print out the function or function graph trace using ftrace, but ...
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Applying patch file to ubuntu server

Can someone please explain how to apply a patch file to ubuntu server kernel? I'm trying to apply this patch file which enables the tcp_collapse_max_bytes option in the TCP communication options on an ...
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How to install kernel-devel for kernel 4.4 in Centos 7 -- yum install attempts to install for version 3.10

I am running Centos 7, which defaults to kernel version 3.10. In order to install drivers for a specific piece of hardware, I seem to need kernel version 4.4 very specifically. When I try to run yum ...
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Kernel error while doing sudo apt upgrade

How to solve the following persistent error: sudo apt upgrade Setting up intel-i915-dkms (0.6379.0.28.221103.25.5.17.0.1020+i46-1) ... Removing old intel-i915-dkms-0.6379.0.28.221103.25.5.17.0.1020 ...
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Lower system call perfermance on aarch64 vs. x86-64

Does anyone know why system calls take longer to execute on 64-bit ARM (aarch64) compared to 64-bit Intel CPUs (x86-64)? Please see below my benchmarking setup. 64-bit ARM CPU: Ampere Altra Q80-30, ...
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NUMA aware caching on linux

This is a follow-up question to dentry/inode caching on multi-cpu machines / memory allocator configuration, but here I try to put the question differently. My problem is that I have a dual socket ...
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Lubuntu booting straight to Grub, sometimes saying cannot load kernel

I recently installed Lubuntu via a USB drive. It works great, but I have found one major problem. Upon booting up my laptop, it opens two one of two things. The first is a Grub command line. If I ...
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What is mnt_cache in slabtop output on Linux?

OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME 5520396 3165734 57% 0.38K 131438 42 2103008K mnt_cache I searched the kernel source code, only 1 hit, and I'm unable to interpret ...
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GPUDirect RDMA on X86 linux PC, driver build issue

I am trying to do GPUDirect RDMA mentioned in the below link. I am using an X86 Linux PC with Quadro M4000 GPU and CUDA 12.0 tool kit. While building the driver and executing CUDA programming, I am ...
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How is a signal "delivered" in Linux?

I am confused by the terminology used to describe Linux signal delivery. Most texts say things like "the signal is delivered to the process" or "the signal is delivered to the thread&...
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nvidia source tree error

I want to install latest nvidia on Debian, i also have an compiled kernel and installation leave with source-tree error and want me to install headers. i also installed late 5X and all 6X headers Here ...
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udev: ID_MODEL is missing at the remove event

When the phone is connected to the computer, udev determines variables by the "add" event. But for some reason, when the "remove" event occurs, there are no variables such as ...
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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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