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

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How to find out what distros are using particular Linux version?

Given a distribution and its version, I can find which version of kernel it uses, e.g. for Ubuntu they are listed here, and for currently supported versions of Fedora they are here. In general, ...
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What does raw_spinlock mean? [on hold]

I was studying struct raw_spinlock which is in the /usr/src/linux/include/linux/spinlock_types.h was like this: typedef struct raw_spinlock { arch_spinlock_t raw_lock; #ifdef ...
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Is there something like “make localmodconfig” that detects *all* your hardware?

I understand that Linux's "localmodconfig" target looks through all your loaded kernel modules and produces a .config file that enables those modules. This is nice, but what about hardware whose ...
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ABRT report says “irq 19: nobody cared”, but why?

Every couple weeks, I need to reboot my system. When I do, and enter as root in the terminal, the following message (in some variation) appears: ABRT has detected 3 problem(s). For more info run: ...
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How to create (or modify) Linux distro? [on hold]

I've read about this and I think that Linux From Scratch is good, however, I'm confused what part I should begin with. My intention is to modify Linux distro - adding or removing some features and ...
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Kernel config for HP Stream 13 (booting from emmc disk)

I'm trying to install gentoo on hp stream 13 device and i am unable to boot up system from the emmc hard drive. Before trying gentoo on this device i have successfully installed debian, which clearly ...
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tRecompile the kernel changing only one option

I've already built a custom kernel based on the mainline 4.1.6. Now I want to disable CONFIG_ACPI_I2C_OPREGION The kernel build doesn't take very short, so I'd like to rebuild only the parts affected ...
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How can I update the kernel and initrd images in EFI boot loader?

I have successfully installed the EFI boot loader (using ELILO) but I am unsure how to actually keep the kernel images up to date. Can you help me understand the process please? Thanks. ...
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Why is debug_putstr() not being printed during boot?

I'm asking myself why debug_putstr() in arch/x86/boot/compressed/misc.c is not being printed during x86 boot phase, though it is configured to do so with GRUB_CMDLINE_LINUX_DEFAULT="". On other ...
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check-config errors on Linux 3.19.0 kernel, configured under Ubuntu 15.04 x86-64

I'm new to configuring Linux kernels, and am receiving the following errors when running config-check: check-config: /tmp/tmp.tnqExc0fHn/CONFIGS/amd64-config.flavour.generic: loading config ...
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scripts/checkpatch.pl: Warning: consider using a completion

I'm currently writing a kernel driver that involves moving large amounts data from userspace to or from a peripheral, via a ring of bounce buffers. The buffer completion callback ups a semaphore, and ...
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Best way to approach HID_MAX_USAGES kernel errors?

This is an issue I have for the second time now: basically, an USB based device reports some wrong numbers for "HID_MAX_USAGES", resulting in the kernel giving an error message and the device not ...
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What is “state-object” in cgroups

I am gathering some idea about lxc, kernel name spaces and cgroups. While reading man lxc-cgroup, i find : lxc-cgroup gets or sets the value of a state-object (e.g., 'cpuset.cpus') in the ...
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Stack pointer of the interrupt stack

Linux kernel has separate stacks for user mode and kernel mode process and also some special stacks. One of this special stacks is interrupt stack with the size 16 kilobytes placed in the ...
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37 views

Linux modules take a lot of space [closed]

I'm using the 4.1.2 mainline kernel. The package with image and all modules has 207 MB of installed size. I built a patched 4.1.6 kernel, taking the config from the current kernel and now the drivers ...
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Does MySQL processes run in user or kernel modes?

I try to count IOPS and I/O size with SystemTap script and use MySQL to be workload. I found mysqld doesn't call systemcall but mysqld has read/write on VFS. So, do MySQL processes run in user or ...
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Error while trying to compile/install kernel, 4.1.6 on Ubuntu 15.04

I'm trying kernel compilation in Linux for the first time. I'm using the guide here to learn the basics. I'm able to pull the source code from the git repository, and can compile it. However, I run ...
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X stopped working after a kernel update

My system is a laptop with Ubuntu 14.04, with an Intel CPU and Intel + Nvidia GPU combo. After one automatic kernel update, the GUI stopped working. It shows a blue loading screen with a spinner, up ...
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What's the philosophy behind delaying writing data to disk?

In Linux, a finished execution of a command such as cp or dd doesn't mean that the data has been written to the device. One has to, for example, call sync, or invoke the "Safely Remove" or "Eject" ...
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how to set i2c bus to soc audio codec

I'm working on an audio codec driver for cs4245 device. It's controlled by i2c. I have 2 hardwares (devel-board), one of the them has the codec attached to i2c-1 and another to i2c-2. The first one is ...
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147 views

How to add a system call in linux kernel 4.x

I'm trying to add a system call using linux kernel 4.1.6 but all the documentation I can find is for older versions. Does anyone know how it's done in the newer kernels or have any good references? ...
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how practical the number of cores in Android

I've often wondered how practical the cores usage in Android smartphone. I'm asking here because Android is based on Linux. I'm looking from technical perspective. The articles that I've read so far ...
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Does this bug indicate an error in my btrfs filesystem of simply a bug in the 4.2.0-RC5 kernel?

I'm not sure this is the right place to ask this... I have been running a pre-release kernel (4.2.0-rc5) and yesterday had a possible disk error on my 6-disk raid-1 btrfs filesysystem. While trying ...
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Retrieve parent pid [migrated]

I am new to kernel module progrmming. In my program I need to display the process name and its parent's pid. The following is my simple_init() function int simple_init(void){ printk(KERN_INFO ...
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How do I track down why my system is unstable?

I am experiencing a problem where I use Chrome on my X220 with CentOS 7 (kernel 3.10.0-229.el7.x86_64). It begins when I've been surfing Chrome for a bit and have a few tabs open. Chrome may just ...
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What module in the kernel that inform the DHCP client to start DHCP negotiation?

DHCP client is a process instead of kernel code. How the DHCP client know when to start sending DHCP discover message? Is it the IP module in the kernel that inform the DHCP client?
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login shell (bash) - how to we invoke a login shell

I know what is a login shell and the difference between a login shell and a non-login shell. But what puzzles me is how it is invoked. It is said that a login shell is invoked with a - as argument ...
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Status of UVC 1.5 support in Linux

My (Debian 8) kernel, 3.16.7 only detects the Logitech C930E webcam as UVC 1.0 (when it does support 1.5). Searching the Internet only throws up kernel patches, most of them from Pawel Osciak form ...
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42 views

Wifi driver on Kernel 4.x

I've upgrade my kernel from 3.19 to 4.1.5 but the Wifi driver don't work. Does anyone know how I can make it work? I've tried a few methods but it doesn't work. First method I've tried was to try ...
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How to compile a third party driver in to the kernal? [duplicate]

I am using Linux Mint 17.2 on Toshiba c640. As my LAN driver is no more functional, I am using a USB to LAN converter which was provided with some driver installation files. Every time i want to use ...
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How to compile a third party driver into the kernel?

I am using Linux Mint 17.2 on Toshiba c640. As my LAN driver is no more functional, I am using a USB to LAN converter which was provided with some driver installation files. Every time i want to use ...
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New Kernel does not automatically reconnect to network

I tried playing around with compiling my own kernel. Everything is fine so far, except for that one thing. Whenever I leave a wifi network or unplug my ethernet cable the system does not recognize, ...
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iptables - why do I get “Table does not exist (do you need to insmod?)”

I need to install some iptable ruels to block traffic that originates from a certain country, I found this script example on http://www.cyberciti.biz/faq/block-entier-country-using-iptables/ it works ...
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How does Linux kernel know that collisions occurred in Ethernet collision domain?

Let's say that I have a following network topology: Theoretical total(Tx + Rx) bandwidth for all four hosts in total is 100Mbps. Now if I execute Iperf in UDP mode in all four hosts simultaneously ...
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Windows Internals for Linux [closed]

I've recently been reading Windows Internals version 6 (from Microsoft Press), and found it thoroughly enjoyable. I'm now using Kubuntu on my work machine, and as such have some desire to learn a bit ...
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Test program to configure MPLS datapath in Latest Kernel 4.1.3

Latest Kernel supports MPLS datapath in kernel, However there is no test program, or any guide how to write user space program to configure a MPLS datapath in kernel. I browse the kernel code and ...
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39 views

Linux Userspace PCI driver options? (uio_pci_generic)

I have a Xilinx FPGA PCIe end-point on the PCI Bus. Linux picks up the device just fine and everything in lspci looks perfect. My question is about PCI access options from user-space and what would ...
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Increasing Kernel Mode Setting (KMS) scrollback buffer size

I'm using Kernel Mode Setting to set my server's tty resolution. I added GRUB_GFXMODE=1280x1024x24,auto to /etc/default/grub, and GRUB_GFXPAYLOAD_LINUX=keep was already there. There's no vga= or ...
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Unable to install new kernel in ubuntu server. “gzip: stdout: No space left on device” error even though abundant disk space

I am trying to install a new kernel on Ubuntu Server and I am unable to complete it due to a "gzip: stdout: no space left on device" error. The full error was produced after running sudo make ...
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Understanding the relation between FreeBSD kernel configuration file and actual device

To my understanding, FreeBSD's kernel is configured via text files. Each kernel configuration entry is on a single line. Many entries also have comments set off with a hash mark. The GENERIC conf. ...
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How do i apply this patch to my current kernel?

i am trying to install this patch to my current kernel /usr/src/linux-headers-3.19.0-25 in order to use the gspca module for a keychain camera device. i tried running patch command and the result ...
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debian testing hangs on wakeup from s2disk / hibernate

My machine (ThinkPad x230) hangs on wake up from s2disk or s2ram after a recent aptitude safe-upgrade.† The hang looks like a blank screen with a blinking cursor in the upper right after loading data ...
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is it possible to run ubuntu kernel on fedora root filesystem?

My concern is theoretical possibility of running ubuntu kernel with fedora root filesystem (e.g. 3.2.58 ubuntu kernel on fedora 22). It's long story why I need this.. Also, I have no chance to make ...
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Uboot pass arguments to kernel!

How uboot can pass command line argument to kernel? I did some googling and got to know that it uses bootargs environment variable.There it was mentioned that setenv bootargs key=value.Since I am ...
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CONFIG_NF_CONNTRACK is not set

I am trying to setup iptables on udoo quad but I hit a brick wall and cannot find a fix anywhere: root@udoo:/# uname -a Linux udoo 3.0.35 #10 SMP PREEMPT Wed Jul 30 18:16:10 CEST 2014 armv7l ...
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How to get the name of USB driver in use in linux

I'm running Ubuntu 14.04 on my laptop. I'm having USB related issues in my laptop. It works sometimes and sometimes doesn't. I thought of fixing the issue myself. So, I wanted to know if there is a ...
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grub2: error: /vmlinuz-3.16-ucs109-amd64.efi.signed has invalid signature

I am using a derivative of Debian, called Univention Corporate Server. It's a nice appliance that I use for my home server. Yesterday I upgraded to the newest version and since then my server does not ...
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Option to configure Linux kernel to run userspace script when core dump occurs?

Is there any option in the kernel compilation or userspace setting to do the above? I'm looking to add a crash reported to my new embedded Linux system.
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What could cause dropping cache to be extremely slow on a large cluster?

I'm attempting to time file I/O on my disks. In order to make sure all the I/O is happening off the hard drives and not from ram, before I time any read, I run a drop cache command. Specifically, I ...
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SLES official repository connection (activation code available for SLES 12, not SLES 11 SP3) solution: use SLES SP4

How could I connected to official repository from my SLES 11 SP3? I need to update my kernel etc. Here my previos active-search post =) How to get 60 day SLES activation code