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

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How to understand virtual switch in Linux?

I have a following virtual Ethernet switch in Linux: root@vmhost:~# brctl show br0 bridge name bridge id STP enabled interfaces br0 8000.266b04c4a79a no ...
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1answer
86 views

Find out which kernel source files were used when kernel was compiled

I am compiling the Linux kernel for my specific hardware and I only select the drivers/options which I really need. This is in contrast to a typical distribution kernel, where they compile almost ...
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git: show which files have changed between kernel 3.18.6 and 3.18.7

I have checked out linux kernel git repository git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git I know how to use git log, git show and similar commands to see ...
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MMU-less kernel?

I would like to try compile mmu-less kernel. From what I found in configuration there is no option for such a thing. Is it possible to be done?
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966 views

How to rotate the LCD screen/framebuffer to 180 degree?

I have a custom board with a Freecale i.MX6Q SoC. I am using Linux kernel 3.03.35 and LCD is 3.5 inch RGB type display. I want to rotate my LCD screen to 180 degree. I tried a lot to pass parameters ...
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How to insert a modified ELF loader given the current ELF loader is present?

I need to modify the ELF loader's kernel implementation of an Ubuntu 14.04 distribution. Having downloaded the sources using: sudo apt-get source linux-image-$(uname -r) I ran the configuration ...
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18 views

dracut md5sum boot directory

This has been going on for a few months now, but my initramfs (and kernel) for that matter have been placed in /boot/{some hash}/{kernel version}/{initramfs,linux}. Did dracut or some other module ...
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191 views

make: xscale_be-gcc: Command not found

I'm new to embedded and am reading 'Embedded Linux Primer' at the moment. I tried to build an xscale arm kernel: make ARCH=arm CROSS_COMPILE=xscale_be- ixp4xx_defconfig # # configuration written to ...
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1answer
223 views

Re-enabling the console once the kernel is up, if silent mode was set in Uboot?

I have enabled the silent mode by setting the U-boot env variable "silent". Uboot-> setenv silent 1 Uboot-> saveenv Now, I would like to re-enable the console once the kernel is up. Can ...
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45 views

Is it safe to upgrade kernel manually on a system which is using NVIDIA drivers?

Upgrading kernel manually on Ubuntu 14.04 can cause trouble with NVIDIA drivers? (one of the troubles could be booting to black screen) I had lot of trouble with installing NVIDIA graphics drivers ...
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217 views

Trying to make a Universal Makefile

I'm working on my own netfilter module for the first time. According to internet documentation, The simplest module contains the following C code: //'Hello World' kernel module, logs call to ...
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1answer
206 views

Why do we need a usbkbd driver when there is usbhid?

I discovered that it is the usbhid that controls my USB keyboard by default. I discovered it by doing rmmod usbhid. When I removed usbhid the usb keyboard stopped working. Note that usbkbd was not yet ...
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630 views

What are the `some_name.o.cmd` files?

What are the some_name.o.cmd files that I see in Linux's kernel code? are they auto-generated?
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Centos 7 boot up with custom kernel problem

I have installed centos 7 on virtualbox machine which has kernel-3.10.0-123.20.1.el7.x86_64. I am trying to build Linux kernel from kernel sources. I downloaded the kernel source files from: ...
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479 views

Corrupt LVM metadata header after kernel update

I'm running Debian Wheezy (Linux wheezy3.2.0-4-amd64 #1 SMP Debian 3.2.63-2+deb7u1 x86_64 GNU/Linux) as an encrypted LVM with hardware raid 1 (Adaptec 6405E) on a supermicro server. I was encounting ...
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2answers
398 views

RTC time synchronization not working (CONFIG_RTC_SYSTOHC)

I have the option CONFIG_RTC_SYSTOHC enabled in my kernel: Device Drivers ---> [*] Real Time Clock ---> [*] Set the RTC time based on NTP synchronization The help says: ...
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96 views

How/Where to learn about linux kernel? [closed]

I want to learn how the Linux kernel works, specifically about the following topics: structure, programming design, device development, but I do not know of good places to learn about these topics. I ...
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2answers
91 views

Linux Operating System and Version, Regardless of Distibution [duplicate]

I would like to know a linux command that can tell me the operating system and version regardless of what distribution I am using as it seems different distributions have a different way of doing ...
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1answer
376 views

Enabling ethernet over USB support in Linux kernel

How to enable Ethernet over USB support in Linux kernel? Which driver (like CONFIG_USB_USBNET) is related to this support? Is EEM (Ethernet Emulation) regarding this support or not?
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modinfo when a module was compiled into kernel statically wouldn't work — workarounds?

modinfo is rather useful tool when it comes to tweaking module's parameters (at least discovering what options are availalbe), for e. g.: $ modinfo dummy filename: ...
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1k views

Buildroot - missing i2c kernel modules

I've used Buildroot to build a minimal operative system. During the configuration step with the menuconfig utility I specified to install I2C tools. The option was is Target Package -> Hardware ...
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2answers
6k views

How to list all loadable kernel modules?

I'm looking for a few kernel modules to load i2c-dev and i2c-bcm2708. But the modprobe command returns: sudo modprobe i2c-dev modprobe: module i2c-dev not found in modules.dep How can I list all ...
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995 views

update kernel without restart

Recently Linux got a new feature called Live Kernel Patching, which you means you dont have to restart your system to update kernel. Is there any other kernel which has this feature already or Linux ...
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21 views

What setsockopts() 'name' values are used by the running Linux kernel?

I am introducing some new socket commands with nf_register_sockopt(&my_new_socket_options). How can I find, what setsockopt commands are already used (registered?) by the currently running kernel, ...
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2k views

dmesg: pci BAR 7: can't assign io

I have VMware virtual machine running Debian Wheezy. I have compiled my own kernel 3.14. I have noticed dmesg is flooded with messages pci BAR 7: can't assign io (size 0x1000). I have no idea what ...
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kernel: nf_conntrack: table full, dropping packet; Underlying Reason

I have a modified linux on an ARM9 processor. It was working OK, but yesterday I got this error repeatedly: kernel: nf_conntrack: table full, dropping packet I have 2 questions: How can I find ...
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38 views

How is the linking mechanism so fast in the kernel system calls? [closed]

If I open any file in Linux kernel almost every file has many extern functions and many #indef or #ifndef macros so while compiling how exactly does it map all the functions and macros when more than ...
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Detecting and categorizing device drivers in a running system

How can I obtain what device drivers are incorporated in a running kernel? More than this, how can I categorize these device drivers? For instance, this is a Linux kernel conceptual map, from ...
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936 views

Can a zImage be used with U-Boot and ArchLinuxARM?

I am using U-Boot on a Cubieboard 2, sun7i AllWinner A20 board to boot into ArchLinux ARM. The kernel version that I have is the sun7i latest, which is 3.4.103-5-ARCH so, in kernel terms, it's a bit ...
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2answers
1k views

“Last resort” Linux terminal command to reboot (over ssh) in case of a kernel bug?

I have a small server with Ubuntu 10.04 on it; I am manipulating this server from another computer via ssh, and I tried to use nfs on it to share files. That mostly works, until one of the clients ...
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519 views

module scsi_wait_scan not found on CentOS kernel-ml causes kernel panic on boot

I am attempting to upgrade from kernel-lt to kernel-ml, following the instructions here, however on boot the console is flooded with module "scsi_wait_scan" not found This leads to a general kernel ...
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What is “fs” short for in kernel function “get_fs()”?

There are two Linux kernel functions: get_ds() and get_fs() According to this article, I know ds is short for data segment. However, I cannot guess what "fs" is short for. Any explanations?
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Why is there AF_NETLINK? Is AF_UNIX not enough?

As far as I understand, AF_NETLINK socket protocol is for communicating between the kernel and userspace and AF_UNIX is for communication between two userspace processes. Why does Linux need a ...
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What does “task mysqld:xxx blocked for more than 120 seconds” mean?

We are troubleshooting a MySQL issue where some queries are taking a very long time complete and I see many of these entry in /var/log/messages: Jan 28 05:52:15 64455-alpha01 kernel: [2529273.616327] ...
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1answer
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Looking for ancient kernel source

I'm looking for an specific old kernel source namely 2.6.26.5 to build an exact replicate of an cross toolchain for an embedded target. Unfortunately all I can find is 2.6.26 in the kernel.org ...
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CentOS/Kernel v3.18/Thunderbolt2

I just got a new SuperMicro box with a AOC-TBT-DSL5320 Thunderbolt2 card pre-installed. I installed CentOS 6.5,ran yum update, and then, because to my understanding at least, thunderbolt support was ...
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Can I masquerade a kernel uevent?

What I think happens From my understanding this is what happens when I connect a USB device to my computer: Kernel recognizes that I plugged in a USB device Kernel setups the very low-level things ...
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1answer
299 views

Cannot update new kernel for CentOS 7 although the server have space enough

I try to update kernel on my CentOS 7 but the yum say there is no space enough on /boot although /boot have 343 MB as show below: Filesystem Size Used Avail Use% Mounted on /dev/sda2 477M 105M 343M ...
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Meaning of an ampersand prefix in a device tree

I am looking at a DTS file which tries to specify different nodes, but interestingly I find a few nodes having different style of nomenclature. / { model = "TI AM335x BeagleBone Black"; ...
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Applying Linux rt patch

I'm trying to apply the rt-patch to the standard kernel from kernel.org. So far I have tried 3.14 and 3.10 from here: https://www.kernel.org/pub/linux/kernel/projects/rt/ with the corresponding ...
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1answer
575 views

Why does microsoft contribute to the Linux kernel? [closed]

Why does microsoft contribute to the Linux kernel? [L. Latif, theinquirer, 2012 "Microsoft contributed more code than Canonical to Linux since 2.6.32"] Are the contributions focussed on code that ...
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1answer
220 views

Change the kernel in downloaded Ubuntu Image [closed]

I'm adding multiple new system calls to kernel. I want to test my custom kernel by making an bootable ISO out of it trying to boot on another machine. As a part of making this bootable ISO, I got ...
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1answer
59 views

Why is necesary to compile the entire kernel for a simple patch?

So I am patching my kernel to fix my Bluetooth and building using this guide https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel Why do I have to compile the entire kernel which takes about an hour?
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69 views

ITEAD Core A20 cant load or Proceed to the FileSytem

i have an ITEAD CORE AW2041, which i wanted to deploy some image on it, i got the image on an sd card but when i deploy it on the device, the booting process gets stuck at the kernel level, any heads ...
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1answer
4k views

Why autoconf.h is not copied automatically to its place?

I'm working on a clean Debian 7.7 install. After the install everything was working fine except the webcam in Iceweasel browser. After reading a lot I found that the best solution is to install ...
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1answer
2k views

Fix grub v2 bootloader configuration on running debian

We have a server running Debian Wheezy. It is connected to a UPS, that's why it basically never went down for years and we never noticed that the grub v2 bootloader could not load the correct kernel ...
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734 views

rebuilding my grub2 menu based on my one installed kernel

tl;dr : I have one kernel now on fedora and want that ONLY with Windows 8 to show up on my boot menu. I've been tweaking and geeking with linux kernels. Then I wanted to clean up my boot menu. So ...
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Investigating Active MemInfo

I am seeing high Active usage when I do a cat /proc/meminfo : MemTotal: 65965328 kB MemFree: 51640992 kB Buffers: 1050332 kB Cached: 8516112 kB SwapCached: 0 kB Active: 11512732 kB Inactive: 1878028 ...
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How to prevent kernel or any broadcast messages from flooding the TTYs?

Because of some hot-plugging issue, similar to what talked of here, the TTY displays show a continuous stream of messages (which are also logged in the /var/log directory). Every text I key in flows ...
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431 views

linux/shell command to control screen brightness in android

I am working on a kiosk project using an android tablet.If there is no input power to the kiosk for a long time then, the tablet will eventually shutdown.In order to auto-reboot the tab when the power ...