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

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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 communicationg between two userspace processes. Why does Linux need a ...
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1answer
366 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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5 views

MAC to MAC MII interface not working

I have a MAC to MAC MII interface between MPC8569 processor and BCM68610 controller , whose schematic design is followed from here. My linux kernel version is 2.6.32. I want to ping one device from ...
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2answers
29 views

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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4answers
20k views

Enabling IOMMU in the kernel for graphics card pass-through

Short question: How can I turn on the intel_iommu setting in the Linux kernel? I run a Debian host, using the grub2 bootloader. Documentation I've seen says to edit /boot/grub/menu.lst, which seems ...
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2answers
2k views

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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3answers
4k views

Why is the theoretical RAM limit for RHEL 6 128 TB and how is this determined?

I'm studying for RHCSA and am confused by a statement I came across in some training material: There is no practical maximum RAM, as theoretically, you could run 128 TB of RAM on RHEL 6. But ...
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1answer
46 views

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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29 views

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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1answer
477 views

Determine whether kernel built-in driver supports a device

I'm trying to find a way to accurately determine whether all the hardware on some system has a valid driver installed either via a kernel module or built-in to the kernel. I'm working with RHEL 5.5 ...
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8 views

Writing kernel driver aio_read, aio_write support [migrated]

I'm currently about to write aio support for a kernel module I wrote for communication with a fast device (125 MB/s) in an embedded environment. To get started, I wanted to look at a few examples on ...
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7 views

haproxy - in CentOS is running but the whole directory is no more available and i do not have configuration backup

I had haproxy configured in /var/tmp directory by compiling, i did not had any backup after few months its still running but my /var/tmp/ is having no haproxy anymore. Can anyone please recover it i ...
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1answer
25 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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4answers
8k views

How to update CentOS 6.5 to kernel 2.6.32-431?

I need to update my CentOS 6.5 kernel to 2.6.32-431. Running yum clean all && yum update doesn't do it for me. How do I update? And what could be the issue? [root@centos64 ~]# uname -r ...
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3answers
12k views

What does “INFO: task XXX blocked for more than 120 seconds” exactly mean on Linux?

I had this message in my kernel log : INFO: task XXX blocked for more than 120 seconds. I would like to know what it means technically: under what conditions does the kernel display this message about ...
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2answers
932 views

How do I search the linux kernel mailing list archives?

I want to research why a Linux kernel feature appears to be missing from my Linux install by searching the Linux kernel mailing list for recent discussions on the subject. The only site that I've ...
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1answer
30 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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24 views

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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8 views

Adding a System call in linux kernel 3.5 [migrated]

I am trying to implement system call to print hello world in linux kernel 3.5 running in virtual box Here is the source of implementation ...
29
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7answers
18k views

Linux Kernel: Good beginners' tutorial [closed]

I'm interested in modifying the kernel internals, applying patches, handling device drivers and modules, for my own personal fun. Is there a comprehensive resource for kernel hacking, intended for ...
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4answers
6k views

Are FIFO, pipe & Unix domain socket the same thing in Linux kernel?

I heard that FIFOs are named pipes. And they have exactly the same semantics. On the other hand, I think Unix domain socket is quite similar to pipe (although I've never made use of it). So I wonder ...
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1answer
29 views

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
66 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
38 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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2answers
1k views

Ping IP works, nslookup fails. New Kernel

I am compiling my own 3.14 kernel. I fear I may have left out some important networking feature to get DNS working. I can't resolve domain names. I can ping my DNS server. I can resolve using that ...
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1answer
41 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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1answer
2k views

bnx2: Can't load firmware file “bnx2/bnx2-mips-09-6.2.1b.fw”

I just compile the kernel 3.10.19 from kernel.org Support for bnx2 is enable. On my server when I try to start the eth0 interface I got the following error : bnx2: Can't load firmware file ...
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3answers
596 views

Using real time kernel headers to compile userspace code vs default headers

Per customer requirements, I installed CentOS 5.6 with the default kernel. With this kernel installed, the time.h file includes the #define CLOCK_MONOTONIC. Now, a real-time kernel was installed ...
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2answers
775 views

File system CRC check

I know that before running the kernel, u-boot (the boot loader) will check the kernel image CRC. Only if it is correct it will go further, else it will give a "Bad CRC" error. I want to do same thing ...
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1answer
40 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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1answer
22 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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57 views

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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3 views

Doubt about kswapd reclaimation? [migrated]

In kswapd page reclamation flow what is difference between shrink_zone() and shrink_slab(), which pages are included in zone lruvec and shrinker_list. I want to know which pages are added in lurvec ...
9
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3answers
955 views

kernel: Namespaces support

I am wondering what exactly the “Namespaces support” feature in the Linux kernel means. I am using kernel 3.11.1 (the newest stable kernel at this time). If I decide to disable it, will I notice any ...
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2answers
2k views

How many actual developers work on the Linux Kernel

For a study I am doing I was asked how many actual developers commit on a typical kernel version. I know there is Linus Torvalds as the main developer, followed by many second main developers. ...
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1answer
568 views

Enable kernel's net_key, inet_esp, crypto_hmac modules for to use in a VPN

I'm trying to turn on modules for VPN so I followed this tutorial to compile new ubuntu kernel 3.8.6 . But the features I've turned on using make menuconfig seem not to be enabled. (the features I ...
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22 views

Trying to understand the wacom tablet plugging in usb causes kernel panic

First, I realise that askubuntu exists, but a kernel panic is probably more GNU/Linux (kernel and low-level system programs) than distro specific. So I already have a solution to mitigate the kernel ...
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1answer
42 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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3answers
389 views

AES-NI on Dell Vostro 3360

I don't have AES-NI available on my Dell Vostro 3360 laptop. Why? Does this machine not support it? My /proc/cpuinfo: processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 58 ...
14
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1answer
3k views

What happens in each step of the Linux kernel-building process?

I've read many tutorials about how to build custom kernels and boot Ubuntu using those kernels, and successfully followed the guides and booted custom kernels, but I have no understanding about what ...
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1answer
63 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 ...
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2answers
55 views

Where can I find the kernel configuration on each Linux distribution?

I'm pretty sure that all Red Hat and Debian based distributions follow the convention of shipping the kernel configuration in /boot/config-*, but what of other distributions? Or, if this convention ...
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0answers
3 views

Help hooking sys_recvmsg to hide a socket from ss (educational rootkit) [migrated]

My question is this. After hooking, finding the nlmsghdr structures, finding the inet_diag_req structures, I change the port number in a inet_diag_req struct (to 56666). Then copy the message from ...
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2answers
32 views

How to switch cores? [closed]

i am supposed to be writing a code in C++ wherein i should switch the core amidst performing a task(a simple program). My machine is a dual core system. Can anyone please help me out here? ThankYou!
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1answer
78 views

How do I install wpa_supplicant on bare embedded (ARM) linux (3.0.8)?

Environment FriendlyARM mini210s Linux 3.0.8 armv7l Cross-compilling I need to install wpa_supplicant, how do I do that? Shall I get the source for wpa_supplicant and place it somewhere in my ...
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2answers
2k views

USB set to /dev/sda instead of /dev/sdb

I've been trying to use a kickstart file to guide the Red Hat installer (RHEL6.5) without user intervention. It correctly looks for the kickstart file in /dev/sdb/fs.cfg, but because the USB is ...
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1answer
1k views

How to fix make error “No rule to make target 'menuconfig'” when building a kernel for Beagleboard?

The aim is to build and install the USB Video Class (UVC) module, via make modules_install. I'm trying to configure the kernel via make menuconfig on Angstrom distribution, running on BeagleBoard-xM. ...
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2answers
744 views

Is TRESOR included in the latest kernel?

Did TRESOR get included in the mainline Linux kernel? Where would I look to find out? Is there any documentation describing its use? Reading about cold boot attacks on Wikipedia makes me think TRESOR ...
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26 views

Little slow downs in Embedded Linux application

My team is working in an embedded Linux solution for a product where a center application receives and process data from the hardware and sends it to a database and to the interface application. In so ...