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

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Running assembly program as ring 0

I'm writing an application which reports back readings from CPU temperature sensors, and the fan speed monitor. However, according to the Intel documentation on PECI, the instructions required must be ...
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What's the exact behaviour of the command: ip address change?

I have been fiddling with IPv6 and address lifetimes. I found out that the valid_lft attribute will make a v6-address disappear automagically, if used correctly. To extend an address' lifetime I would ...
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72 views

Built the kernel with NFS support but not getting /dev/nfs

I'm trying to build kernel 3.13.9, fetched using apt-get source, and built in a clean debootstrap chroot (both host and chroot being installations of Ubuntu Trusty). My goal is to boot a diskless ...
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38 views

tasklet and interrupt handler synchronization [closed]

The things I know about tasklet: Tasklet runs with all interrupt enabled. The tasklet runs in interrupt context. It can't sleep. It runs in atomic way. It has the assurance to be scheduled never ...
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49 views

Can 32 bit applications on a 64 bit kernel use all the memory?

I know that the 32-Bit kernel can use PAE to allocate more RAM to applications with PAE (up to 64GB) as such I imagine if I am running 32 bit applications on a 32-bit kernel I can use all of my 24GB ...
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60 views

I/O schedulers for normal harddisks

For me figuring out what is the best choice for I/O in kernel was a challenge. First I learned that it is subjective then it is depend upon the File-System you use. I know you should use No-op for ...
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64 views

View all disabled or hidden linux kernel options

I am trying to build a 3.12 Linux Kernel and I see some of the options (sub menus) are hidden and their branch (menu entry) is disabled in make menuconfig. [---- instead of being --->] I know ...
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448 views

What is equivalent to Mac's purge in Linux?

In Mac I use purge to free up some memory. What is equivalent to it in Linux(Ubuntu Server)? apt-get install purge gave me nothing. If you are no familiar with Mac's purge here is it's man page: ...
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66 views

Testing the Success of a Congestion Algorithm

How do you test whether a particular congestion algorithm is working for you? I ask because it's not as if I can easily re-create a representative workload for most algorithms. I'm current looking at ...
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80 views

How do I make strace “decode” AF_NETLINK comminucation like with ioctl?

strace usually "deciphers" ioctls, showing what do they mean, even resolving network interface names and so on. But the same operation performed using AF_NETLINK stays opaque in strace. How to teach ...
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What are the two head.S files in linux source ?

In the linux source there are two different head.S files located at: arch/arm/kernel/head.S arch/arm/boot/compressed/head.S What is the puprpose of each one and what is the order of there execution ...
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What is the purpose of patches of the linux kernel?

For each Linux kernel version, there is a patch file available for download. For instance, linux-3.12.22 has a corresponding patch-3.12.22. What is the purpose of that patch? To always patch the ...
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98 views

kernel source code for beaglebone black

I want to build an Ubuntu kernel from scratch for beaglebone black. I have been searching for where I can download the kernel source code for more than two days but haven't found anything. So, ...
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23 views

Driverless Windows webcam supported by UVC under 3.10 kernel?

There are 'driverless' webcam that plug into Windows 7 and will work directly without driver, in same way as USB finger disk, just plug in and work automatically. Is it true that the mechanism works ...
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230 views

Installing linux-3.14.8 un Arch Linux while 3.15 is already in testing

I'm currently running kernel 3.14.6 on Arch Linux from Core repo. I would like to install 3.14.8 (which is the latest of 3.14 series) because it contains a fix that is suitable for me. However linux ...
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1answer
46 views

Red Hat internal specifications

I'm doing a homework assignment for my college, and I'm trying to find the parameters used in kernel compilation on RedHat. My teacher asks: "Analyse and describes in terms of models of each version ...
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58 views

Understanding the difference between pid_max, ulimit -u and thread_max

I am trying to understand the Linux processes. I have confusion on the terms pid_max, ulimit -u and thread_max. What exactly is the difference between these terms? Can someone clarify me the ...
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121 views

Server won't boot, kernel panic - not syncing

After a reboot of a CentOS 6.2 server we are getting a kernel panic with the following error: Kernel panic - not syncing: Attempted to kill init! Panic occurred, switching back to text console ...
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185 views

Why does this iptables rule doesn't get configured after a reboot once in a while? [closed]

On my Android network device, iptables firewall rules service script is started by the init.rc scripts during boot time. One of the firewall INPUT chain rules doesn't get configured in the iptables ...
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67 views

kdump doesn't produce core dump after buggy module is loaded

I am running kernel 3.14.4 on Fedora 18. I am experimenting with a kernel module I am making. The module has a bug (at least one) and crashes the kernel. Sometimes I see a stack trace on my frozen ...
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5answers
119 views

How to find a Linux kernel that works ok on my PC?

I have an old laptop. The newer kernels that ship with the latest versions of the most popular Linux distributions crash from time to time. I want to use a new Linux distribution to get the latest ...
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1answer
119 views

Kernel 3.14.1 compilation errors

I installed the kernel 3.14.1 and there seem to be no issues. uname -r 3.14.1-031401-generic However, when I try to go to the folder and try to do a make it fails. I see that multiple files are ...
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44 views

kernel event listener

I wonder if there is something similar to an event listener in UNIX that a program can subscribe to? Specifically I want to know: Start and end times of a user session Start and end of the ...
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EDAC (Error Detection And Correction) infrastructure in linux kernel

I am wondering how I can make use of the EDAC infrastructure in linux kernel. I have a i7-4600M CPU and I have compiled EDAC as a module in my kernel: --- EDAC (Error Detection And Correction) ...
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Adding IPVS to the kernel

I am trying to setup keepalived on a pair of VPS load balancer servers. I have hit the road block of IPVS not being included with the kernal. IPVS: Can't initialize ipvs: Protocol not available I ...
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63 views

Extremely slow CD-ROM burning

When I try to burn a CD-ROM using K3B, the burner slows down from 10x to 0.12x after writing exactly 71MB. Consequently, burning a 142MB live CD takes more than a hour. Why is this happening? The ...
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booting freezes after used scheduler greatest stack depth error

I have built the linux kernel 3.14 with debug info. When I tried to boot it gives following error and after that booting freezes. Can somebody tell me how to fix this ? Linux Version : Slitaz in ...
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92 views

Black screen after installing Arch Linux, conventional fixes don't work

I recently installed Arch Linux on my HP Pavilion dv6 (Radeon HD 6770m graphics card) to dual boot with Windows 7 by following the beginner's guide found on the Arch wiki. After grub loads, I choose ...
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144 views

Library routines in linux kernel

In the linux kernel, there is a section "Library routines" with a snippet shown below: Library routines ---> <M> CRC-CCITT functions <M> CRC ITU-T V.41 functions <M> CRC7 ...
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56 views

Why does kernel-devel contain so many “empty” directories?

I have been a Windows kernel developer for many years. Now I start to develop Linux kernel modules. To begin with, I installed kernel-devel under /usr/src/kernels/$(uname -r). However, after checking ...
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98 views

custom kernel and firmware loading

After I have compiled my kernel, and when I type make modules_install, not only are the modules copied into /lib/modules/ but also firmware is copied into /lib/firmware/. The following is the end of ...
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35 views

Black screen when kernel boots with vga= parameter

Recently recompiled kernel refuses to do output on the screen if vga parameter was in the list. Without it kernel boots properly as usual, however, before that it changed resolution and RC log ...
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Disable kernel logging during initialization

I'm using a Linux image generated with buildroot for an embedded system. I recently disabled some modules from being generated with the image and now some logging messages are being shown during the ...
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181 views

Kernel panic when passing noatime in bootargs

I have an embedded system using jffs2 and want to pass rootflags=noatime in the kernel bootargs parameter. This results in a kernel panic: jffs2: Error: unrecognized mount option 'noatime' or ...
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110 views

Compare two kernel config files from the menuconfig perspective?

I have a situation in which i have two kernel config files (for the same kernel source ). Both of them have a part of the functionality that i need (on one, USB works correctly, on other, the second ...
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128 views

How to enable printk selectively?

I want to print some statements from kernel but not all. So can I use printk selectively? By selectively I mean I want to enable printk only at particular places and disable it everywhere else. ...
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How to interpret cpu_idle and cpu_frequency event's trace logged by ftrace?

I used ftrace to trace two events, cpu_frequency and cpu_idle. I am not able to find out any documentation which states how to interpret this information. I have provided two snippets from the ...
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1answer
72 views

Can a Linux distro be closed source?

According to the GPL licence, which is the one used by the Linux kernel, every modification in the source must be open source too. But, for example, if I create a new OS based on Linux, I develop my ...
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1answer
98 views

How to Connect Internet in Zedboard using Linux via SDCard

I am working on Zedboard Zynq 7020. I have booted the Linux via SD card through Zedboard. The linux display can be shown onto the monitor via VGA cable. But I cannot connect that linux to internet. ...
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Error while installing wireless-bcm43142-dkms-6.20.55.19: dependency linux-headers is not satisfiable

I have to install a .deb file with the firmware for the wifi card (This is the name of the file: wireless-bcm43142-dkms-6.20.55.19_amd64.deb; I've downloaded the file from here: ...
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1answer
84 views

Bluetooth headset profile not working with recent kernel

I have a Plantronics 590 bluetooth headset (the type probably does not matter, but I have no alternative to test). Using the old 3.02 I was able to use this via pulseaudio. With the current ...
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1answer
120 views

Booting using initramfs instead of uramdisk

I am working on Zynq Microzed board. It is booting perfectly with uramdisk.image.gz but I trying to boot it with initramfs.cpio. In this regard I have made following changes in header files of ...
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164 views

Kernel hangs at “bootconsole [earlycon0] disabled”

Booting petalinux on Microzed board (ARM-Cortex A9). Compiled source code, DTS, and fpga.bin. Every thing is going fine till it hangs at "bootconsole [earlycon0] disabled" I am using ...
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No CD-Rom on IBM 9228 with 631xESB/632xESB IDE Controller

I've got an IBM 9228 Server running Gentoo Linux. Everything works except for the CD-ROM drive, which is connected via a PATA cable/controller. I know the CD-ROM works and is connected correctly ...
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1answer
45 views

How are the different kernel naming schemes relate?

I am running Ubuntu 13.10 with the Kernel 3.8.0-030800-generic downloaded from http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.8-raring/ When I want to run for example turbostat or cpupower ...
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1answer
36 views

Why is the .config file not copied to /boot after installing new kernel?

I run across such a weird problem: According to this: The kernel and modules must be moved to special locations in order to be used, 1. make modules_install 2. make install The first ...
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LXC container to use “virtual” interface from host (namespace semantics)

So according to the documentation on the Ubuntu LXC documentation the following statement can be found at the time of this writing: A NIC can only exist in one namespace at a time, so a physical ...
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filesystem that works under qemu and I can mount on my host

I'm using qemu for different kind of tasks, I would like to pick a filesystem that is both qemu-compatible and easy to mount under my host. I already discarded both qcow and qcow2 because apparently ...
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Getty instances in init process

Init typically will start multiple instances of "getty" which waits for console logins which spawn one's user shell process. Upon shutdown, init controls the sequence and processes for shutdown. The ...
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295 views

Conceptual difference between Linux and (Free)BSD Kernel

(I've already noticed that this question was asked before but I think it has not been answered in a way I'd like to understand the topic.) What are the conceptual and structural differences between a ...