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

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Turn off camera driver in Android programmatically?

How can I turn off camera driver in Android programmatically? According to this website, and the image below, there's a camera driver inside the linux kernel. Is there a way to disable it temporarily?...
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Exactly what aplications and tools are not installed in a GNU/Linux base-system installation [on hold]

They are a lot type of installations like netinstall, the distro with a DE or without one. My question is what are the excluded or ingnored packages and aplications in a base-system installation. E.g. ...
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vmlinuz <-> uImage

I would like to ask if I can make a regular kernel build with cross compiler (make uImage), and then move it into ubuntu machine (replacing vmlinuz in some way). This is can save me a lot of time, ...
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how do I know if and why linux is killing my processes?

I'm working on one of amazon's linux distros (4.4.11-23.53.amzn1.x86_64). (1gb ram)on that instance I am running node.js with the forever module. (It makes sure to restart the node.js process if it ...
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How to to insmod a module build with linux-headers-generic?

I have been trying to make a kernel module, but have run into problems due to the non-standard kernel I am using. I cannot find the headers using repositories, and have not yet been able to get help ...
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Building debian kernel package with custom configuration

I'd like to build a jessie kernel with my configuration. For that: I download an original tarball of the kernel, debian tarball for the kernel, and "dsc" file. Issue a command dpkg-source -x ${...
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2answers
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How do you modprobe a program?

I've been trying to get this program to work on my Raspberry Pi for the past two days and I've gotten to step 6 which says, "At this point, you should be able to modprobe v4l2loopback". When I ran ...
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1answer
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How to deal with high number of page faults?

I've got ~200000 page faults per second and I think it's a huge number and it affects the overall system performance. I'm using MBP with 16G of RAM. How to deal with such number of page faults (...
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How does the native_cpuid() x86 function set the Extended Processor Info and Feature Bits? [closed]

The following function from the Linux kernel is a C implementation for utilizing the CPUID call in ASM. static inline void native_cpuid(unsigned int *eax, unsigned int *ebx, ...
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27 views

How to allow access to memory in a kernel module? [closed]

Suppose I have a memory-mapped peripheral which can be read from or written to at some address, say 0x43C00000. I want to be able to read from that same memory location in my Linux OS in order to ...
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Marking TSC unstable due to check_tsc_sync_source failed

My dedicated server has been hanging it out (or just turning off) very often sometimes more than a day, apparently for no reason (according with the technical support department). After that, the only ...
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Why does the OOM-killer not log details to be visible through dmesg?

I want to make kernel oom_killer run and provide the related log entries in dmesg. I set the following settings echo 1 > /proc/sys/vm/overcommit_memory and tried to fill up the RAM to it's max, ...
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Process Family Tree: list_for_each() [migrated]

I'm reading about Process Management in Robert Love's Linux Kernel Development. He's writing about how one can use the following code to iterate over a process's children struct task_struct *...
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2answers
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Can initramfs programs access all memory - do they run in real or protected mode?

This is in the context of current 64-bit processors and current linux kernels (I'm using 4.6.4.) Is it possible for me to write a program that during boot can examine base memory, 640k and under, ...
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1answer
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Downgrade XUbuntu kernel

I'm now running XUbuntu 16.04 with kernel 4.4.0-31 and now I need to somehow downgrade kernel to version 4.1.24. Is there any way to do that?
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Running a program after system startup directly from the linux kernel

I am trying to run my application directly from the linux kernel (without using cron or something similar). I've tried using ./init/init.c, but it runs too early: $ dmesg ... [ 0.605657] TEST!!! ...
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How to prevent access to HDD during Live-CD operation?

I want to safely disable the harddrive / harddisc (HDD) of my computer with boot parameters. I can not physically unplug it. BIOS / UEFI does not provide me an option to disable it. Can I use the ...
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1answer
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Black screen with blinking cursor after trying to boot Kali, Ubuntu, and Lubuntu live

I recently bought a Lenovo Thinkpad Edge 15 (Model: 031925U) on Ebay. The machine came with Windows 7 Pro 32 bit installed. I replaced the HDD with a 240GB Samsung 750 Evo. With a 2.4Ghz i3 370M ...
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Which Kali Linux kernel image should be chosen and why? What is the difference?

Among the following, which Linux kernel should be chosen and why? How does each of them differ from vanilla kernel? What is meaning of grsec, bpo, rt and dbg? What kind of functionality do they add ...
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After updating the Red Hat server kernel to latest version it still shows as old version

I have updated the kernel on my Red Hat Enterprise Linux Server release 6.7 (Santiago) from 2.6.32-573.22.1.el6.x86_64 to 2.6.32-642.1.1.el6.x86_64 and as per Red Hat documentation https://access....
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Can't determine cause of a crash

I have a PC that is freezing periodically. Sometimes it will crash 2-3 times within a couple of hours, while other times it will go a few days. When the PC crashes, the screen, mouse, and keyboard ...
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1answer
24 views

How should I debug a hard-lockup of my Ubuntu laptop

I've been running Ubuntu on a Thinkpad T450s for some time now. Every so often, the system will hard-lock on me. E.g. the mouse won't move, ctrl-alt-f# won't take me to a plain terminal, etc. I ...
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New Kernel from Backports does not boot

I tried to install the new Linux kernel 4.6.0 on my Debian machine from backports, but my machine won't boot with the new kernel. Steps that I took: added BPO to sources.list apt-get install ... (...
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Difference between intel-driver and GPU

I have a i7-6700 HQ and therefore a HD Graphics 530 integrated However I'm confused about "what-is-what" in my system since my kernel is using a driver called i915. Is this the "main" driver for ...
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APT-Pinning Kernel

My plan is, that my kernel is updated from the testing-repository of Debian. So that if I do a dist-upgrade, the kernel will be automatically upgraded. My Problem is, that the dependencis aren't ...
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Where the remaining memory of vm.overcommit_ratio goes?

If I disable memory overcommit by setting vm.overcommit_memory to 2, by default the system will allow to allocate the memory up to the dimension of swap + 50% of physical memory, as explained here. I ...
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package-cleanup --oldkernels won't clean out an old 3.x kernel with 4.x kernel installed

I think package-cleanup is getting confused and thinks only 1 kernel is installed. Centos 7.2 I had a single 3.x kernel installed. I then installed kernel 4.x using rpm -Uvh http://www.elrepo.org/...
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430 views

kernel update - WARNING: lvmetad is running but disabled. Restart lvmetad before enabling it!

I just updated one of our debian jessie servers and the kernel was updated, nothing special, as we have done this many times. But the first time there were some warnings when the grub configuration ...
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USB g_serial bug? - loosing data in one direction

I am having some difficulties with kernel module Gadget Serial v2.4. g_serial is used on ARM machine BeagleBone Black with Arch Linux 4.6.3-1 which is communicating with host PC. The problem was ...
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Attempting to compile any kernels, even vanilla ones, yields a certification error (continued from last thread) [duplicate]

(Accidentally lost previous account after crashing my computer without saving keepass information. Continuing thread here). I'm currently attempting to follow this guide in order to install the 4.5....
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Linux or Unix for Isp providers? [closed]

For an ISP providers without thinking about cost and which one is open source or close source. Consider only performance!!!! which one is better than another?and why?
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Looking for an old linux distro for testing [closed]

I'm currently looking for a very old Linux distro that has an old kernel, doesn't support PAE/XD bit, doesn't support VASLR (Virtual Address Space Layout Randomization) and doesn't have X^W memory ...
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3.10 kernel changed how it handles scsi / udev behavior

This is a nfs booted kernel and custom initramfs to execute code on bootup. Here is dmesg after that piece completes and pivots into the running file system. https://paste.fedoraproject.org/387110/...
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Integrate last V4L in 3.14 Kernel

I'd like to integrate the last version of V4L in a 3.14 kernel sources that I'll compile later. Today with a runinng kernel, if you want to update your Video 4 Linux because one device is not ...
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Make a bootable ubuntu-core for Raspberry pi2

I've been trying to build a minimal Ubuntu system for my raspberry pi2, based on an Ubuntu 14.0.4 core (base) image. here: wiki.ubuntu.com/Core I deployed the image to the SD card, Cross compiled a ...
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Why is ulimit -u higher than /proc/sys/kernel/pid_max?

On my system ulimit -u reports 63172 and /proc/sys/kernel/pid_max reports 32768. Why is it that the value for ulimit -u is higher than the kernel's value? From my understanding, ulimit -u shows the ...
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I would like to unload kernel modules that show as busy

I want to unload the modules "gsch and redirfs" from kernel on RHEL 7.2 , which is causing frequent kernel panic. But when I try to unload , I am getting below error. # modprobe -r gsch modprobe: ...
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what does dequeue_task_fair() do in linux scheduler [migrated]

this is a function in linux scheduler, in the implementation of COMPLETELY FAIR SCHEDULER which is in the path: root/kernel/sched/fair.c (link to the file) Now I want to know what does this function ...
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Kernel parameters “console” and “earlycon” refer to old hardware?

I first found this by investigating parameters for earlycon but found that the options for console look almost identical. Both are present below and were taken from this source: From documentation ...
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Linux kernel GRUB/boot issue?

I'm working with a specific software package that is only compatible with a older linux kernel version. After installing this older version via the following command $ sudo apt-get install linux-...
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1answer
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Booting kernel (FIT image) with no rootfs

An embedded Linux device I am working with has the following kernel parameter: root=/dev/ram0 Additionally, the kernel image is bundled together with an initrd and device tree to make a flattened ...
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1answer
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Does the format or columns of /proc/dev/net change often?

I'm writing a script to scrape some data from this. I'm wondering if this file changes often or is different between distros.
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3answers
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How was kernel written? [closed]

Running a program in kernel mode forbids using standard C library because the only thing your program linked to is kernel itself. So I'm allowed to use functions defined in kernel. But kernel itself ...
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How to run a function for a specific received packet? [duplicate]

I am doing an experiment for my master thesis. I want to run a function (e.g. multiply two numbers) when a specific packet is received (e.g. a packet with destination TCP port 6666). For example, I ...
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I'm unable to further install solus 1.2

Because once i enter the installation process it is automatically having an higher resolution than what my monitor can support. What changes can i make in any kernels to make the installation process ...
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Error calling EVIOCSKEYCODE

I used journalctl -p 3 -xb and got this error message -- Logs begin at Thu 2016-06-23 22:48:08 AST, end at Sat 2016-06-25 13:15:23 AST. -- Jun 25 09:31:35 Almoullim systemd-udevd[268]: Error calling ...
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1answer
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Why does reading /proc/net/tcp take a long time ss is quick to return the same sort of data about the connections table?

On Linux 2.6.32, if you read (for example, cat) /proc/net/tcp, on a very loaded system (for example, a web server), you will find that reading 100K entries takes over 30 seconds. That's a long time. ...
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Force dirty pages limit in kernel sources

First of all, I'm not sure if that's a solution to my problem. My problem is that during I/O embedded linux is allocating too much memory in cache causing OOM if I run anything else. I/O operations ...
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1answer
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Embedded Linux OOM - help with lost RAM

I have little Linux system with 256MB RAM. I'm little bit confused, where the RAM may be lost? It is running old linux kernel 2.6.38 and I'm not able to ubgrade it (some specific ARM board). SHM and ...
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1answer
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modprobe events not logged in /var/log/messages

I'm trying to understand Linux better, specifically driver registration and such so I'm trying to follow what happens when I insert modules and drivers. From what I thought I understood, kernel ...