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Questions tagged [linux-kernel]

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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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I have an external I2C device that signals when data is ready using a pin. I want my Linux SBC to trigger I2C transfer routine after GPIO interrupt triggers. How would this be done within kernel space?...
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For those who don't know, UBSAN is Undefined Behavior Address Sanitizer, and it places a whole bunch of checks in a compiled piece of code to detect mistakes, such as out-of-bounds access and various ...
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I’m encountering a recurring kernel memory error while running heavy PyTorch training workloads . The system eventually becomes unstable, training stops, SSH disconnects, and the machine needs a ...
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I have a linux-box. My hdd is nvme, hence boot is fast. I need to analyze each line of after grub. Can I pass a kernel parameter to capture my boot lines?
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OSTEP says Note that CFS utilizes a periodic timer interrupt, which means it can only make decisions at fixed time intervals. This interrupt goes off frequently (e.g., every 1 ms), giving CFS a chance ...
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The goal is to create a mirror (aka raid1) device from two devices (to be mirrored), and (if needed) a third device that serves as the dirty region log / metadata / whatever. That, without using LVM ...
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I have a cloud VM running linux-yocto 6.17 and a few daemon processes--postfix, dovecot, rspamd, nginx, sshd, fail2ban and redis. Ever since upgrading from 6.11 to 6.17, I've noticed that /proc/sys/fs/...
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I would like to find out why my power button press isn't handled correctly. I've set power manager in XFCE4 to 'ask' me, but all that happens is I'm getting logged out of my session. I have contacted ...
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The Issue I am reading this systemd documentation I have the following files: /usr/lib/systemd/network/80-wired.network [Match] eth0 [Network] Address=192.168.3.40/22 Gateway=192.168.0.1 /usr/lib/...
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I'm troubleshooting /boot usage differences between Oracle Linux 8 systems that use different UEK kernel streams. On some hosts, the initramfs images are gzip-compressed, while others produce ...
chriscrutt's user avatar
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I know the Linux kernel has a key retention service even though I haven't used it myself. I'm constructing a system where anybody with root cannot check the keys in that service that were registered ...
Gwangmu Lee's user avatar
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I am experiencing a problem when booting Linux on the Verdin Dahlia Carrier Board, where the boot log only goes up to: ################################################################# ###########...
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I tried to upgrade my alpine linux kernel version from linux-lts to linux-stable because support for a device I am installing was added in a newer kernel version. I changed the apk repositories from ...
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Why does there appear to be a discrepancy between a process stack address within /proc/PID/maps compared to the stack start address within /proc/PID/stat, where the latter is a smaller subset of the ...
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Hardware / OS: Laptop: Lenovo Legion 7 16IAX10 BIOS: RXCN23WW (from sudo dmidecode -s bios-version) CPU: Intel(R) Core™ Ultra 9 275HX (from lscpu) Distro + kernel: EndeavourOS / Linux 6.17.2-arch1-1 ...
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I am trying to implement request steering in Linux kernel’s blk-mq layer to distribute I/O requests across CPU cores based on load. My goal is to redirect requests from busy cores to less busy ones to ...
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If you would open a listening socket on every possible TCP/UDP port (so thousands in total), without actually using them, what would be the cost in terms of performance? Is it merely an administrative ...
Maestro's user avatar
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Here's an example /proc/crypto entry: name : md5 driver : md5-generic module : kernel priority : 0 refcnt : 1 selftest : passed internal : no type : shash ...
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We have kernel dirty bytes settings configured as below. vm.dirty_background_bytes = 262144000 vm.dirty_background_ratio = 0 vm.dirty_bytes = 0 vm.dirty_expire_centisecs = 0 vm.dirty_ratio = 10 vm....
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I'm trying to bring up a WWAN modem on a Dell Latitude 7455 laptop running Linux. The modem is connected via PCIe domain 0005, but that PCIe controller is currently disabled in the default device tree....
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I have 5 USB-over-IP hubs with 16 usb ports, also in future can have some hubs with 64 usb ports, and all should be connected to one virtual machine. But in Debian by default 15 usb port from one host ...
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I came across the following quote in this LWN article: Answer: On all systems running Linux, loads from and stores to pointers are atomic, that is, if a store to a pointer occurs at the same time as ...
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I'm running the Nvidia flavour of Ubuntu 18.04 with kernel 4.9.140 on a TX2i using the official devkit carrier board. The system suffered a watchdog reset. I managed to capture some log output over ...
Felix Collins's user avatar
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I have laptop from 2025 (Lenovo Legion Pro 5 16IAX10 Ultra 7 255HX) and Fedora don't recognize the CPU: $ sudo dmesg | grep microcode [ 0.000000] x86/CPU: Model not found in latest microcode list [ ...
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I can't figure out how swap limitation should work based on the documentation. https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html memory.swap.max A read-write single value file which ...
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I am using keyctl to load and retrieve keys for encryption/decryption for an application. I notice I am able to retrieve the key id of an encrypted key (for example called 'datakey') which has already ...
ani's user avatar
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This question comes from my curiosity about how Kubernetes handles resource requests and limits, especially memory constraints defined for pods. I understand that Kubernetes uses cgroups under the ...
Nicola Sergio's user avatar
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4 votes
2 answers
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I'm compiling a customized kernel for vm without module support. The CONFIG_BLK_DEV_SR is compiled into the kernel, but it /dev/sr0 still not showing up in /dev: # qemu-system-x86_64 -accel kvm -...
William's user avatar
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If I'm working on contributing to a Bluetooth driver, but don't have the actual chip available. How can I test functionality and debug during development without the physical hardware? Does anyone ...
Wen's user avatar
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The following logs have appeared Aug 12 17:51:23 host1 kernel: iwlwifi 0000:02:00.0: enabling device (0000 -> 0002) Aug 12 17:51:23 host1 kernel: iwlwifi 0000:02:00.0: Detected crf-id 0x2001910, ...
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After updating with pacman -Syu system fails to boot. ERROR: device '/dev/lvmSystemXXX/volRootXXX' not found. Skipping fsck. mount: /new_root: fsconfig() failed: /dev/lvmSystemXXX/volRootXXX: Can't ...
alex's user avatar
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There's no wireless interface show in the network icon and none in when I type 'nmcli device' running dmesg shows [130854.349171] mt7921e 0000:05:00.0: probe with driver mt7921e failed with error -22 ...
John Porterfield's user avatar
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Before running echo 2 > /proc/sys/vm/drop_caches the active page count was: Active(anon): 36185016 kB after the flush, active page count became: Active(anon): 26430472 kB every other ...
Roman's user avatar
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1 answer
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I am trying to make mdadm call into a simple bash script which writes a message in the kernel log in case of a state change. I am running on a VM (qemu). The VM is running debian 12.5, and kernel ...
Haris's user avatar
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I am analyzing issues with unexpected increase of memory consumption in Linux. It is an embedded system with no swap. What is happening is over some period of time around 2GB of MemFree/MemAvailable (...
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The problem is while booting up rasbberry pi with uboot as boot loader not able to decrypt encrypted rootfs partition with initramfs,to debug and analyse what happening want to enable uboot debug logs....
URegal's user avatar
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1 vote
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We are currently testing tiered memory demotion on a machine equipped with a CXL device. To facilitate this, we created a specific script (https://github.com/hyun-sa/comem) and are using the memory....
Hyunsa's user avatar
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1 vote
1 answer
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I've recently purchased an NVIDIA RTX 5070 Ti, but it doesn't work properly under Linux. The card works perfectly under Windows 11, so hardware failure can be ruled out. When the PC boots, I can see ...
Aurélien's user avatar
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4 votes
2 answers
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How can I take snippets from the Linux kernel drivers' code, for example this drm_fb_helper_hotplug_event function inside drivers/gpu/drm/drm_fb_helper.c, and compile a binary file that I can run to ...
feearent's user avatar
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I'm aware of Linux softirqs may run within specific per-cpu kernel thread context -- ksoftirqd/[cpu_id]. Kernel threads are similar to user-space threads, however they only execute kernel code in ...
CarloC's user avatar
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4 votes
2 answers
259 views

On Linux, it's possible to disable overcommitting memory which makes it behave like Windows, in that malloc() will fail once all physical memory is used up. As explained in this insightful and good ...
E. K.'s user avatar
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Here is quick description what im trying to achieve, building this mender yocto image for raspberry pi want to encrypt the root partition, while secure boot, need to add the init script which can ...
URegal's user avatar
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9 votes
2 answers
3k views

How do I kill a process that cannot be killed? user@kubuntu22:~$ ps -ef |grep smbd nobody 3532354 1 0 16:30 ? 00:00:00 /usr/sbin/smbd --foreground --no-process-group user@kubuntu22:~$ ...
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1 answer
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I tested out echo 2 > /proc/sys/vm/overcommit_memory, which I know isn't a commonly used or recommended mode, but for various reasons it could be beneficial for some of my workloads. However, when ...
E. K.'s user avatar
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I want to test and debug linux kernel internals within the bluetooth stack, i.e. /net/bluetooth. I have a (rather minimal) kernel, manually built, with debug symbols, and a busybox at the moment, ...
nox's user avatar
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1 vote
2 answers
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I expected to see a list of address ranges starting with 0xffff..., but /proc/vmallocinfo gives some crazy unpadded values. I'm cooking Mali GPU drivers for OrangePi Zero 2W, and was wondering why the ...
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10 votes
3 answers
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According to Linux Kernel Development by Robert Love, p. 233: Because of hardware limitations, the kernel cannot treat all pages as identical. Some pages, because of their physical address in memory, ...
Andymang's user avatar
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How do you enable hardware flow control for the Linux serial console? Perhaps using GRUB arguments? This post asks about specifying arguments to QEMU and GRUB to use the serial console, but doesn't ...
atod's user avatar
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I'm tyring to boot linux on an SoC (arm64 based) and seeing trap in early stage. Here is the boot message. Booting Linux on physical CPU 0x0000000002 [0x411fd401] Linux version 5.15.68 (etri@AB21-T07) ...
Chan Kim's user avatar
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Is there a way to get struct msghdr or ancillary data of it for the last received packet, i.e. after the recv() call? My guess is that recvmsg() is the only way to populate msghdr, but probably there ...
Alex's user avatar
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