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Questions tagged [kernel]

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

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How does linux arbitrate access to devices

I would like to know the different methods linux uses to control access to a peripheral device. e.g. for example you have a spi temperature sensor. And multiple threads are trying to get a reading. ...
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31 views

How to cause a kernel panic on modifying source code

I need to make a simple on Linux Kernel source code to cause kernel panic on boot. How to do it ? in which file should I modifying? UPDATE: I don't need a command, I need a modification in source ...
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Mapping from uname -m to /usr/src/linux-headers/arch/*

I'm building an eBPF program. For it to build I need to add as include paths (-I) some headers located in /usr/src/linux-headers-*/arch/x86/include. Since this path is x86-specific, to be able to ...
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1answer
51 views

How is the Linux kernel partially written in assembly when system calls are required? [on hold]

Does the kernel just not use system calls, or is the assembly being assembled before being on a new system? I might need some more info on assemblers, but I'm just confused that if instructions such ...
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1answer
21 views

Custom built kernel supposedly not usable on amd64 during preseeded installation

I need a more up to date kernel than what even buster ships with (5.1.x to be precise) due to the hardware I'm using. Building that kernel is nor problem whatsoever 8building it with make deb-pkg) and ...
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14 views

User mode Linux can't run – It aborts immediatly after execution

When compiling UML – kernel 5.1.2 – with the following configuration CONFIG_64BIT=y CONFIG_X86_64=y CONFIG_BINFMT_ELF=y CONFIG_HOSTFS=y CONFIG_LBD=y CONFIG_BLK_DEV=y CONFIG_BLK_DEV_LOOP=y ...
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1answer
27 views

spin_lock vs. spin_lock_irq vs. spin_lock_irqsave

There are three spin_lock functions in the kernel I am currently busy with. spin_lock spin_lock_irq spin_lock_irqsave I only find contributions covering only two of them (including Linux ...
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17 views

Kernel not booting in new kernel

After upgrading kernel (2.6.32-754.12) linux (6.10) boot stucks in progress bar...even if I press esc key to identify process where it stopped -- only getting black screen....while in old kernel ...
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22 views

Unload running kernel module

With lsmod I can watch all kernel modules that running in my linux. How can I suspend and resume spesific kernel module? I tried use modprobe -r <module_name> but got error can't change ...
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23 views

Kernel Panic on a Custom Kernel: Unable to get to the dump-capture kernel

I'm running Scientific Linux 6.10 ( CentOS / RHEL Clone ) with a custom compiled kernel 4.18.9. I'm using a recent install of kexec since the one that comes with SL 6.10 is not recent enough to work ...
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1answer
32 views

Process getting killed by SIGKILL

I am running an algorithm on a server and the algorithm takes long time to get finished. But for some reason, the process is getting killed automatically. I am not sure exactly the reason for it and ...
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11 views

Find a power_supply of type

My kernel driver needs to access battery's properties (get_property, set_property). Problem: How to find the battery's struct power_supply? I only find power_supply_get_by_name but there can be ...
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1answer
35 views

unable to launch any program: trap int3 ip error

I cannot launch any program in my desktop environment. I get these errors in dmesg: traps: terminator[3670] trap int3 ip:374dda71261 sp:388624bbec0 error:0 traps: pcmanfm[3685] trap int3 ip:...
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Using kgdb to debug the Linux kernel on two laptops without a serial port, is this possible?

I want to use one laptop as a development machine and another laptop as a target machine. https://www.kernel.org/doc/html/latest/dev-tools/kgdb.html "Two machines are required for using kgdb. One of ...
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1answer
22 views

Difference between CONFIG_RANDOMIZE_BASE and CONFIG_RANDOMIZE_MEMORY in Linux kernel config

This page says that RANDOMIZE_BASE is for KASLR and it randomizes the physical AND virtual addresses which is obvious in 32-bit and comprehensible in 64-bit. But what does RANDOMIZE_MEMORY do exactly?...
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1answer
40 views

In netstat tcp is listening for SSH, but tcp6 is not listening, In sshd_config, i have both ipv4 and ipv6 what will the problem?

While running the SSH demon, only ssh for tcp is listening, tcp6 is not getting listened, even though sshd_config file contains both Ipv4 and Ipv6. Due to this, ssh demon is not replying for ipv6 ssh....
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9 views

Should I remove watchdog when using kdump

Is it safe to enable both the watchdog and kdump when expecting to catch a kernel crash? Specifically, I'm using hardware iTCO_wdt and software watchdog. If I get in a situation where kdump starts to ...
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3answers
56 views

Why is lsblk showing the old FSTYPE and LABEL of a device that was formatted?

I formatted an external hard drive (sdc) to ntfs using parted, creating one primary partition (sdc1). Before formatting the device SystemRescueCd was installed on the external hard drive using the ...
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0answers
18 views

What's the policy determining which CPU handles which interrupt in the Linux Kernel?

I've been reading Linux Kernel Development and there's something that's not entirely clear to me -- when an interrupt is triggered by the hardware, what's the criterion to decide on which CPU to run ...
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25 views

Run a single process that can fork and clone as a non-root-user

I wish to run a docker container which runs a single os process, forks a clone of itself through invoking '/proc/self/exe'. This process will be launched by a user of the container, who may be a ...
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9 views

Hibernate Arch GNU/Linux (without modifying the bootloader)

I have a machine duel-booting Ubuntu and Arch. After running update-grub on Ubuntu, Arch has been added to Ubuntu's GRUB bootloader, allowing me to choose which distro I want to boot into. That said, ...
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1answer
59 views

What's the difference between Intel p-state and speed step from driver point of view? [closed]

In my understanding, they are both adjusting voltage and freq for power efficiency. what's their difference? Linux Intel p-state: https://www.kernel.org/doc/Documentation/cpu-freq/intel-pstate.txt ...
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1answer
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Intel p-state is global setting or can be individually for each core?

My understanding, p-state control freq & voltage for power efficiency. The higher p-state, the more power efficiency. Problem: Intel p-state is a global setting for all cores or can be set ...
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21 views

How to set CPU freq individually?

In my understanding, we can set CPU freq by governor/policy, however, it seems a global setting for all cores. Can we set different freq for each core?
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31 views

Optimizing Linux for desktop responsiveness without thirdparty kernels

The default linux kernel config (at least in Ubuntu and Arch) is not as optimized for desktop responsiveness as linux-ck or Zen Kernel. The difference between those kernels and the default one is very ...
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1answer
46 views

Where is Intel speed select driver? [closed]

According to https://builders.intel.com/docs/networkbuilders/intel-speed-select-technology-base-frequency-enhancing-performance.pdf page 11, linux support SST-BF since 4.20 but I can't find it's ...
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1answer
42 views

About Intel speed select

I am studying intel speed select: official info: https://www.intel.com/content/www/us/en/architecture-and-technology/speed-select-technology-article.html reference site: https://www.tweaktown.com/...
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10 views

Linux Kernel: Redirecting dmesg to a txt file through the kernel space

I understand that writing files through the kernel space is not recommended but I have been porting 4.9 to my Android device. While fixing the display, the device stopped booting(Splash -> Black ...
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0answers
34 views

WARNING: amdgpu dkms failed for running kernel

put amdgpu-pro 18.50. I do not understand, it was established, but does not work? If the error is related to the kernel, then what is the reason? My kernel is the latest version 5.0.9. WARNING: ...
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38 views

Can't load kernel

I'm a Mint user. I was trying to solve a problem, which is that when I suspend my PC I can't resume. I found on stack exchange Ubuntu an answer saying to use "ukuu" in order to upgrade the kernel. ...
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1answer
53 views

Binary executable file with write permission get READONLY from vim

First I know that use vim to write a binary executable program is not recommended. So, I don't want to talk about its rationality here. I have a binary program, with permission 755(owner is root), so ...
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38 views

Why system energy is equal to 1/f? [migrated]

I am studying Intel speed shift. I see a slide: Reference I don't understand, why the green line 1/f means system energy, I think more performance should need more energy as the red line (compute ...
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2answers
123 views

Does linux (kernel) support Intel speed shift?

Windows 10 support Intel speed shift. Does Linux (kernel) also support it? Speed shift related info: https://www.anandtech.com/show/9751/examining-intel-skylake-speed-shift-more-responsive-...
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Kernel manjaro does not load, swap unknown

I need to recover my system...It broke down after a failed update. I tried to google the solution but I got this: [manjaro-deepin manjaro]# mkdir /mnt mkdir: cannot create directory ‘/mnt’: File ...
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34 views

unable to install pop-desktop

Usually I find a way around, but I don't understand what is the problem here: darknmy@pop-os:~$ sudo apt install pop-desktop Reading package lists... Done Building dependency tree Reading state ...
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1answer
36 views

How is the Linux git repo related to other distribution git repos (such as Ubuntu)?

I am trying to build a custom version of my Ubuntu kernel, and want to apply a patch that I see on the main Kernel tree. I know that Ubuntu development happens in these repos: git://git.launchpad....
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How to disable suspension in Linux Kernel 4.x

I am using full disk encryption, through LinuxPBA and sedutil (https://github.com/Drive-Trust-Alliance/sedutil). In short, at boot, a BIOS-independent piece of code requests the disk passphrase. If ...
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0answers
48 views

kernel TCP/IP implementation - about accept queue

I'm recently learning the TCP/IP implementation in linux kernel(version 4.4), and got really confused about the accept queue. I know there is a queue in struct inet_connection_sock which is called a ...
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2answers
117 views

What's inside the kernel part of virtual memory of 64 bit linux processes?

I came upon this question : What's the use of having a kernel part in the virtual memory space of Linux processes? and based on the answer and the comments on the answer : the kernel memory ...
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42 views

How to tune Linux machine in order to improve CPU load average and CPU utilization

We are working with a huge Hadoop cluster. We have 736 datanode machines and each node has 16 cores × 2 threads. On some machines we saw CPU load average (98-128 for 5 min). After deep ...
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53 views

microcode update fail

I saw log: microcode_ctl: kernel version "4.123456" failed early load check for "intel-06-4f-01", skipping Does it mean, the microcode update will check kernel version? We can find a similar log ...
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1answer
67 views

Best way to filter/limit ARP packets on embedded Linux

I have an embedded Linux on some network device. Because this device is pretty important I have to make many network tests (I have a separate device for that). These tests include flooding my device ...
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0answers
64 views

Chuwi Lapbook air 14" touchpad recognized but not fully working

Two days ago my Chuwi Lapbook Air 14" arrived with Windows 10 pre-installed on it. I installed elementaryOS 5 (based on Ubuntu 18.04 LTS) and it works perfectly: recognizes the eMMC drive (the ...
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101 views

kernel does not boot because of rcu_sched self-detected stall on CPU

I'm using a Cubox-i with a self-compiled kernel (previously version 4.19.4). When I tried to upgrade to version 5.0.7 I get the following problem while booting, and the kernel never comes up. I have ...
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How to install Devuan/Debian testing/unstable without starting from a stable release?

It is possible to install Devuan/Debian stable and then editing /etc/apt/sources.list upgrade to a testing/unstable branch (ref). However on my laptop I have an AMD Ryzen 7 2700U processor, which ...
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12 views

Kernel task with very large amounts of data written

While looking for something else completely different, I saw this a tase “kernel_task”; it seems to be writing an outrageous amount of data.
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30 views

Is there a way to find out which process is setting a Linux kernel parameter to an invalid value at runtime?

I have set the kernel parameter fs.inotify.max_user_instances to 100000000, but it is automatically getting set to 1256 after a while. Is there some way to figure out which process is setting it to ...
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0answers
21 views

Kernel-core fail

I use Fedora 29 (xfce), and today it's starts to break my browsers. Appears to me the message: "unexpected error" "the system encountered a problem and recovered" but, it's been happening even me ...
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0answers
19 views

Is there any way to find an associated page with the page under the same VMA?

Assume There are many pages in a random vma. I know the virtual address of page1 0x7f9942c273dc and have a pointer of its struct vm_area_struct vma1. VMA 1 |---- page 1 |---- page 2 |---- ... |---- ...
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43 views

Disabling cpuidle

It seems that there's a bug (race condition) in the kernel's cpufreq code, only discovered from 4.20 on due to some changes in the kernel. I understand it is still an issue in the 5.0 kernel. (read ...