The kernel of operating systems popularly known as Linux, or sometimes GNU/Linux.

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How does Linux kernel find out which process to wake up during interrupt handling?

I was reading the book Linux Kernel Development on Chapter Process Scheduling. On Page 61, section Waking Up, the first paragraph reads: Waking is handled via wake_up(), which wakes up all the ...
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1answer
33 views

What is a kernel-source-tree?

What is the Linux kernel source tree? What does it contain and what is its purpose? I'm trying to build an external module and the tutorial I'm using says to make sure that a kernel source tree is ...
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1answer
33 views

SATA ssd drives

I have a question regarding the support for SATA ssd drives in the Linux Kernel. I read on the internet that one should enable PCI support for proper usage of the sata drives. Could someone please ...
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How “ata_for_each_link” and “ata_for_each_dev” macros works in linux kernel?

I am trying to understanding the SATA device enumeration sequence from the ata_piix.c Host controller driver which resides at /driver/ata/ata_piix.c in linux kernel. During understanding the flow,a ...
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124 views

Netlink access inside a network namespace

I'm trying set up an IPsec gateway (strongSwan) on a Raspberry Pi 2. The Pi was already providing a number of services on the LAN using a private IP address. My initial attempt to turn it into an ...
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2answers
50 views

CPU: 13 PID: 15452 Comm: ssd_blk/0 Tainted: G B I E 3.19.0+ #1

I developed a module which works as an emulator for a block device. When I write into the block device, I get this in dmesg and the module crashes. I cannot get any hint about what is going on? [...
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1answer
68 views

How to change Linux kernel version

I have downloaded and unzipped the Linux Kernel. What file(s) in kernel source file(s) are responsible for displaying Version string in uname ? I want set version to 10, without dots 10.0.5 # uname -...
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37 views

Would a process with the higest nice value use only *free* CPU time

I want to be sure that a scheduled job, mostly using gzip, will not impact the production. This is an old Linux server with few CPU, it has SAN attachment so the gzip is running at its maximum using ...
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45 views

Scratches on the screen (GMA 3600) and wifi is not detected (rtl8192ce) - Debian Stretch kernel 3.2

I'm having trouble in a notebook with debian, but for the avoidance of doubt guess I better tell the story of his free-software life (if you do not want to read, jump to problems) It is a CCE Win ...
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34 views

How to switch static drivers like switching kernel module drivers?

I have a linux embedded device that I need to switch between USB file storage gadget driver and USB Ethernet gadget driver at runtime. The approach I use now is to build both drivers into kernel ...
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1answer
91 views

How does one establish SIGRTMIN at run-time?

Reading up on signal(7) I can see that now: two, but once: three; signal numbers past 31 are reserved for use by the Real-time signal system and should not be used: Real-time Signals Linux ...
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1answer
123 views

Are kernel threads processes and daemons?

From Mauerer's Linux Kernel Architecture, Kernel threads are processes started directly by the kernel itself. They delegate a kernel function to a separate process and execute it there in ‘‘...
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1answer
115 views

md raid5: translate md internal sector numbers to offsets

TL;DR summary: Translate an md sector number into offsets(s) within the /dev/mdX device, and how to investigate it with xfs_db. The sector number is from sh->sector in linux/drivers/md/raid5.c:...
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22 views

Possibilty of DisplayPort over PCIe

I'm trying to figure out if it would be possible to add a DisplayPort to my Linux PC using a PCIe slot. I have found cards like http://www.ebay.com/itm/PCI-E-1x-Express-to-USB-3-1-Type-C-Dual-Port-...
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1answer
145 views

How to make Linux use the right driver (lshw)

I have an Edimax EW-7811Un wireless adapter which I am trying to get to work on my laptop which is running Debian 8.3.0 with LXDE. I have tried various things that I am going to describe below. But ...
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2answers
30 views

Are there sandboxing concepts for proprietary binary kernel modules in linux?

Quite a lot has been going on to advance inter-process security (UID the same) and priveledge dropping in userland, yet it is common that proprietary linux kernel components are used (it seems that ...
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1answer
214 views

Is it possible to get the information for a device tree using /sys of a running kernel?

Commonly for arm systems, device trees supply hardware information to the kernel (Linux). These device trees exist as dts (device tree source) files that are compiled and loaded to the kernel. Problem ...
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128 views

Unable to boot after kernel upgrade

My PC triple boot Windows 10, Ubuntu 15.10 and Kali 2016.1. It boots from Ubuntu Grub. Everything worked fine until yesterday. Yesterday Kali released version 4.4 of the kernel and I installed it. ...
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160 views

Why does it take so long to detect an usb stick?

I'm writing an initramfs-script and want to detect usb-sticks as fast as possible. When I insert an usb 2.0 stick, the detection of idVendor, idProduct and USB class happens within 100 ms. But the ...
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88 views

Extremely high shmem usage

I'm trying to debug the issue that's periodically taking down my work machine. It's an OOM-type problem, and based on this /proc/meminfo output: Total: 32902608 kB MemFree: 4054100 kB ...
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5answers
429 views

Build Linux kernel to boot to Terminal

I am just getting started in Kernel hacking and want to build a kernel that will not launch an OS GUI but instead just go to a terminal command prompt. This is an attempt to debug an issue I'm having. ...
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107 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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1answer
88 views

why process running in kernel mode cannot be preempted [duplicate]

I read that user mode process are preemptive but why not kernel mode process?
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1answer
27 views

Is the kernel module made before or after a new system call? [closed]

I'm trying to incorporate a new system call in the kernel source. However, on checking some resources over the web, I cam across this term called "kernel module". I am confused how to go about it : ...
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1answer
112 views

Raspberry Pi 2 Custom Kernel with initramfs

I'm desperately trying to get a self-compiled kernel running together with an initramfs. It worked on the old raspberry, but somehow I can't get it to run. What I'm trying to do exactly: Load kernel, ...
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1answer
67 views

Unmount a rbind mount without affecting the original mount

Asked on serverfault but didn't get enough attention, so reposted here, with the hope some people here know the answer. There is another question discussing about umounting rbind mounts, but the ...
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1answer
563 views

How to resolve 'netlink: 12 bytes leftover after parsing attributes.' in syslog on Red Hat Enterprise Linux 6.5?

When I install customized RHEL 6.5 with no GUI, on the Virtualized Platform like Esx Server. I am constantly getting, kernel message netlink: 12 bytes leftover after parsing attributes.. And this ...
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1answer
89 views

/boot symlinks do not match current kernel version

I'm a bit puzzled on the following: I have a multi-kernel system, with a default one set by grub.conf, which is the 3.6 ; what I don't understand is why when I list the files in /boot/ I see the ...
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1answer
41 views

How do I find out how my currently Linux kernel was configured [duplicate]

I'm getting no core dumps, and core(5) says the problem might be that my kernel might be configured with CONFIG_COREDUMP, how do I find out if it is true? I'm on Mint 17.3 (uname -a: Linux laptop 3....
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1answer
163 views

Installing linux kernel 4.4.0-trunk-amd64 crashes X server

I have installed Debian 8 and xfce. My machine is Lenovo Ideapad 500S. There's no information for this machine on how to properly use Debian on it. When I install linux-image-4.4.0-trunk-amd64 and ...
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1answer
28 views

How do I check if a specific fix in the Linux kernel has been included in a longterm kernel?

I'm specifically wondering if the patch for this bug has been included in the 4.1 longterm tree, or if it hasn't I'd like to know how best to keep tabs on when/if it does get included. The relevant ...
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FIPS mode, signature verification failed

I am building a kernel with FIPS mode on. I followed most of the procedures described on Red Hat documentation here. I also created a hmac signed .vmlinuz file. After installing dracut-fips and ...
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113 views

Please explain “kobject” [closed]

Hey I'm new into Linux and just started reading Linux Kernel Architecture by Wolfgang Maurer. Right in the beginning of the book he makes a note and tries to explain what kobjects are and their ...
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1answer
59 views

How to dump the dmesg AKA Kernel logs to a single .txt file from the kernel boot?

I am trying to understand the SATA Host-Device Communication and for that I have put a lot of debug messages in the kernel driver code. Now messages are in such a huge amount that I am not able to see ...
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1answer
150 views

Linux file system corruption due to improper shutdown (fs ext4)?

I have been managing many Linux servers, It is very easy to play with Linux servers than any other OS. But Sometime I encounter a problem with Linux OS is that, The file system corruption. This ...
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3answers
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kernel configs and dependencies

When a particular kernel config is turned on, e.g. CONFIG_CRYPTO_FIPS=y a bunch of other dependencies (CONFIG_XXX_YYYY) get turned on during compilation. Is there a way to know all the dependencies ...
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24 views

embedded linux- to check uart in raspberry pi

Checking whether the Pi is sending and receiving UART data by installing the tool Minicom. Pi is sending serial data but is not receiving data. Whatever I type in Pi minicom is received to PC ...
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29 views

Why I can not update Linux core in dockers?

When I run apt-get update && apt-get upgrade in container, the core is not starting to update. Yes, I know, containers use the kernel of host machine and can not execute some ...
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1answer
54 views

Help in building Yocto(open embedded) projects using cluster computing in Linux

I need to reduce project build time in Yocto (open embedded) in Linux platform. So I decided to cluster computers for the best performance for compilation and building. My question: Is there any MPI ...
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0answers
23 views

How connected are kernel modules to kernel version?

I'm wondering how custom ROMs port new versions of Android (particularly the Linux kernel) to old phones. As I understand, Linux allows closed source kernel modules. If so, then when the phone ...
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1answer
245 views

Linux kernel, missing '__fentry__' symbol

Trying to build the EtherCAT master driver (realtime I/O driver) on a RT Linux (SL6.3) I keep bumping into a missing symbol issue when building the EtherCAT kernel modules: # make modules make -C "/...
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186 views

Attach UVC camera to non-V4l2 Android device without rooting

The main issue is arising when I am trying to connect UVC compliant camera having CMOS sensor OV6612, to an Android device having kernel 3.0.x and OS 4.0.x, not having v4l2 driver. And no streamed ...
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2answers
245 views

Troubleshooting new linux system keeps freezing

I just built a new computer and installed centos7 (RHEL based) and I also tried mint 17.3 (Ubuntu based). Installation goes without any problems. The operating system runs smooth and everything is ...
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0answers
35 views

Where in Ubuntu SPI pins are configured?

I'm running Ubuntu on a custom embedded system. The SPI bus master is spi-pxa2xx. I've tried my code on several other systems and it worked fine. But on this system all I see is CS activity while I'm ...
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3answers
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What prevents distributions from using the latest Linux kernel? [closed]

Most Linux distributions ship with a certain kernel version and only update it on point releases (x.y.z to x.y.(z+1)) and for security updates. On the other hand, I know that Linux has a very strict ...
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Remotely use a platform device

I have a linux/android device with a certain hardware module (lets call this pc A), and a driver which uses the hardware as a platform device. Because of testing/os restrictions I'd like to be able ...
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2answers
258 views

Is there any way to hide kernel threads from ps command results?

When I type ps -ef , there are lots of special kernel thread processes showing. I am not interested in kernel threads; I am only interested in user process/thread. Is there a way that I can hide the ...
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19 views

How much control do concrete file systems have over the VFS inode cache and the buffer cache?

I want to make sure I'm understanding how VFS inodes and file system inodes working together. A file system's inodes are stored on the block device and that is where they live. When an operation is ...
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60 views

Booting into linux kernel 4.1.3 using qemu

I am trying to boot into a compiled Linux 4.1.3 bzImage (disabled modules, so I only had to make bzImage). Correspondingly, I installed ubuntu 15.10 (with Upstart, not systemd) on a qemu cow2 image (...
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3answers
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how to monitor a unix directory and if any new file in directory it will be copied to another directory

I want to monitor a unix(Solaris 10) directory and if there is any new file i want to copy immediately. Tried: I have shown inotifywait and incron package in linux for it but i don't know whether it ...