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

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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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40 views

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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2answers
48 views

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
24 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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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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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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yum installs kernel-devel different from my kernel version

I am attempting to install the VMWare player in Fedora 19. I am running into the problem that multiple users have had where VMware player cannot find the kernel headers. I have installed the kernel-...
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Benefiting of sched_autogroup_enabled on the desktop

I am running a 2.6.37 kernel with sched_autogroup_enabled set to 1. I am not certain that I am seeing the benefits of this patch since: I am launching my applications from the desktop; applications ...
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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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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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4k views

How to add boot parameters in arch linux

I want to add i915.i915_enable_rc6=1 as a kernel line as described here but I'm unsure where/how exactly.
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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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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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4answers
5k views

What are the responsibilities of each Pseudo-Terminal (PTY) component (software, master side, slave side)?

I am trying to figure out how a tty works1 (the work-flow and responsibilities of each elements). I have read several interesting articles about it, but there are still some blurry areas. This is ...
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1answer
26 views

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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4k views

Setting up HDMI output from Linux console

I am currently running Debian Wheezy on a HP Microserver N54L with an AMD Radeon 5450 video card. I would like to be able to play audio from the console through the HDMI port of my video card and ...
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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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disable transparent hugepages

We are installing SAP HANA in a RAID machine. As part of the installation step, it is mentioned that, To disable the usage of transparent hugepages set the kernel settings at runtime with echo ...
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Make kernel detect garmin device

I'm trying to connect a usb garmin forerunner device to my system, but the usb device is not detected. I have loaded the following modules: garmin_gps 11544 0 usbserial ...
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3answers
557 views

Does linux modules/drivers belong to kernal space or user space

Some articles say that modules/drivers belong to kernel space as it take part in forming the kernel; (reference: http://www.freesoftwaremagazine.com/articles/drivers_linux) While others say that ...
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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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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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1answer
100 views

kernel messages “lost 9599 rtc interrupts”

I just started getting these messages on my Fedora 23 x86_64 system. Can someone tell me what they mean please? rtc broken or failing? Jun 4 01:32:54 fc23 kernel: hpet1: lost 9599 rtc interrupts Jun ...
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1answer
405 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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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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37 views

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
21 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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176 views

How to Modify Android Boot Sequence in Order to Boot From an SD Card

I've been looking into how to boot Android form an SD card, and I came across this thread on XDA, but I am too much of a noob to understand it, and user has stated that she doesn't have the time to ...
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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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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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what is the difference between spin locks and semaphores?

What are the basic differences between spin locks and semaphores in action?
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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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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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124 views

CentOS 7 unable to cleanly umount a bind mount using rbind and rslave

The following sequence of commands will fail on CentOS 7 (kernel version: 3.10.0-327.10.1.el7.x86_64): [hidden]$ mkdir -p A B/a C/b [hidden]$ sudo mount --bind A B/a [hidden]$ sudo mount --rbind B C/...
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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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1answer
27 views

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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1k views

psmouse sync issues!

I have Compaq CQ61-420US (64-bit AMD) laptop with Synaptics touchpad checked using $ egrep -i 'synap' /proc/bus/input/devices N: Name="SynPS/2 Synaptics TouchPad" But recently after Arch Linux 3.15-...
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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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Scaling issues of i7 3520M with intel_pstate module on Kernel 3.10.0

Few days ago I updated my openSUSE 12.3 system from Kernel 3.9.8-1.gf3348a8-desktop to 3.10.0-1.g3dcd746-desktop and since then, turbo mode of my i7 3520M is enabled by default and it does not ...
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running kernel on QEMU

I face this message: Failed to execute /initKernel panic - not syncing: no init found. Try passing init=option to kernel. I am using this command line: qemu-system-x86_64 -hda disk.img -kernel ...
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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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Why would the kernel drop packets?

I interrupted tcpdump with Ctrl+C and got this total summary: 579204 packets captured 579346 packets received by filter 142 packets dropped by kernel What are the "packets dropped by kernel"? Why ...