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

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Understanding RCU when Configuring the Linux Kernel

I am configuring the Linux kernel version 3.9.4. I am being asked questions about RCU (seen below). Specifically, what are each of these and what are the advantages and disadvantages of enabling or ...
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How to set CONFIG_PREEMPT_NONE in RHEL 6.4 (linux)

I am trying to tune the RHEL6.4 Kernel to handle server style load for of my application. With RHEL 6 scheduler has been changed to CFS and with RHEL 5 my application works fine. I would like change ...
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378 views

mount options shown in /proc/mounts

IIRC then the mount options shown in /proc/mounts have changed. Some time ago acl and user_xattr were shown, now it seems that only noacl and nouser_xattr are shown if these features are turned off. ...
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Determine if reboot is required to update kernel?

I am running a server which runs on CentOS with cPanel (latest version) and I have it set to automatically update using yum. Since it needs to be rebooted in order to update the kernel (and possibly ...
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net.ipv4.conf.all.mc_forwarding: why is my access denied?

On Debian 12.04 LTS I am trying to access the key net.ipv4.conf.all.mc_forwarding by doing : sudo sysctl -w net.ipv4.conf.all.mc_forwarding=1 But every time I am doing this, I get the message ...
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how to get network QoS statistics in linux kernel?

Is there a way to get the bandwidth, delay, jitter collision, error rate and loss rate of a certain link through the interface on a local machine? let's say my machine is connected to a network via ...
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What are some of these directories in the Linux kernel src?

When I uncompress the Linux kernel source code from Kernel.org, there are many folders. I know what most of them contain and their purpose. However, I cannot figure out or find on the Internet the ...
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Can ps display only non kernel processes on Linux?

How can I ask ps to display only user processes and not kernel threads? See this question to see what I mean...
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Theoretical possibilities for cpu emulation built into boot-loader or kernel?

Is it a crazy idea to somehow make a blend of grub and qemu in order to boot linux kernels or any kernel of any cpu type supported by qemu or the built-in cpu? I know it might be impossible to detach ...
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Kernelpanic Fedora 18 with kernel 3.9.2-200

Since upgrading to kernel 3.9 I now get this error every time at start up: BUG: unable to handle kernel NULL pointer dereferences at (null) IP[<ffff8800ca93bfcd>] 0xffff8800ca93bfcc PGD 0 ...
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using devtmpfs for /dev

I have noticed the following option in the kernel: CONFIG_DEVTMPFS Device Drivers -> Generic Driver Options -> Maintain devtmpfs to mount at /dev And I see that it is enabled by default in ...
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I'm failing to set up a wireless Access Point (AP)

I'm trying to get this card to be an access point, and am failing. I tried various Ubuntu releases, and checked on both ARM and i386. The kernel version I used is 2.6.35, and there is no Network ...
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obtaining kernel build tree

Could anyone explain me what the kernel build tree is? What files does it include? How can I obtain it from a cross-compiled kernel source (e.g. 3.4.0)?
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Can't install Linux Headers on Debian 6

I don't understand why this isn't working (I'm stumped!); root@box:/home/user# apt-get install linux-headers-2.6.32-5-686 Reading package lists... Done Building dependency tree Reading state ...
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398 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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Linux snapshotting issues [duplicate]

Is there any way to deal with incoming writes while a backup is in progress in linux. Example, you are writing to your sql database and lvm snapshotting at the same time. This will result in corrupted ...
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176 views

compressed and uncompressed kernel on an embedded device

I have been using several different embedded boards that store kernel, init files, filesystem, etc. on partitions of a (micro)SD card. I notice in the example usage or instructions that compressed ...
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Why does Linux 3.2 kernel (Debian backport) hang during boot?

I wanted to upgrade the Linux kernel on my Debian wheezy (stable) on Thinkpad T60. I installed linux-image-3.2.0-0.bpo.4-686-pae, version 3.2.41-2~bpo60+1. The problem is it hangs during boot, just ...
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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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building/compiling kernel headers

I am compiling kernel 3.4 and 3.8 for different target devices. I would like to install compat wireless driver which requires kernel header. Could anyone tell me how I can compile/build the kernel ...
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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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Real mode and loading linux kernel confusing

As far as know, protected mode will activated in kernel and in grub stage it still real mode. My misunderstanding is: In real mode, total memory available for use is less than 1MB but how grub can ...
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files in /proc/$PID (e.g. ssh-agent, Chrome) are not owned by user but by root

I am just answering another question here :-) and thus had a look – wanted to have a look at /proc/$PID/fd of ssh-agent in order to find out which socket it uses. But I can't. I am quite surprised to ...
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What considerations need to be made when choosing the version of kernel for an embedded device?

I have used buildroot to successfully create a kernel, root file system and cross-compilers to enable me to write application code to run on an embedded device. Currently I have no need to write ...
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What is the relation between the Linux device drivers “domains”?

As I'm reading about the Linux device drivers and power management API I keep encountering terms like "system level", "subsystem", "platform", "class", and so on. What is the relation between them? ...
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Decreasing mouse sensitivity at kernel level

I have developed a custom-GUI Server, which runs on virtual console of Linux.For mouse-handling purpose, it reads the mouse device file /dev/input/mice and retrieves the event data and updates ...
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How do you compile your own kernel on a RHEL6 system?

In RHEL6, the kernel is 2.6.32. What is the procedure to compile your own kernel?
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Does alsa depend on the kernel version?

Lately I had nothing but trouble with my sound setup. The full chain looks like this: alsa (pulse plugin)-> pulseaudio (jack plugin) -> jackd -> firewire soundcard This works fine, except ...
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How do I extract the filesystem image from vmlinux.bin?

jor1k ships a vmlinux.bin. I think there is an initrd inside, cause I don't know where else it would be. I am trying to extract the filesystem image so I can change it, but I don't know how to. I ...
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Why isn't Linux embraced as the official GNU kernel?

While I knew for quite some time the existence of Hurd, and its mission as the official GNU Operating System kernel, I was wondering how come Linux is not embraced as the official GNU kernel over the ...
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323 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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Does linux modules/drivers belong to kernal space or user space

Some articles say that modules/drivers belong to kernel space as it take part in forming the kernel; (reference: http://www.freesoftwaremagazine.com/articles/drivers_linux) While others say that ...
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“Acpi-State” in slabtop's output gets increased — what is it? Is it a bug?

Since boot it gets increased occupying even more RAM than anything else: Active / Total Objects (% used) : 680608 / 719176 (94.6%) Active / Total Slabs (% used) : 17390 / 17390 (100.0%) ...
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How to determine which module taints the kernel?

My kernel keeps panicking when connected to a certain wireless network. I'd like to send a bug report but my kernel is apparently tainted. From /var/log/messages: Apr 17 21:28:22 Eiger kernel: ...
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How should I solicit feedback from a tree maintainer for patches sent to the lkml?

I have submitted a patch to the linux kernel that has gotten several reviews and gone through a couple iterations on the mailing list. It has been ACKed and reviewed by two developers, but they say ...
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how to uniformly execute benchmarks on linux

I am doing project on adapting Linux for scalable multi core architecture. I am testing Linux's performance with benchmarks. When I am running the benchmarks in the system then other programs like ...
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sigaction(7): semantics of siginfo_t's si_code member

I've got a long-running program (becomes a daemon with daemon(3) call) that exits on Signal 11 (Segmentation Violation) every so often. I can't tell why. So, I wrote a SIGSEGV handler, set using the ...
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GRUB2 and kernel vga= parameter

According to the documentation, use of the vga= kernel parameter is deprecated as of GRUB2. The fact that some newer kernels don't seem to support it anymore on certain adapters is of no concern as ...
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Address types used in Linux

I am trying to understand the Memory address types used by the Linux kernel, which are User virtual address Physical address Bus address Kernel logical address Kernel virtual address I understood ...
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What are the other congestion control algorithms specially designed for lossy Wireless Networks like LTE and WiMax?

I am trying different congestion control algorithms for getting maximum throughput and minimum delay across my setup for TCP flow.Please suggest other available algorithms apart from Veno, ...
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Install x11 on my own linux system

I have developed my own tiny linux file system using buildroot and busybox. I used linux-2.6.38.8 kernel configured and cross-compiled for target system(X86) according to needs.Now the filesystem is ...
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Unable to install the selected kernel

I have problem with my DVD drive. It's corrupted and when I'm trying to install Ubuntu it stucks (even with the miniISO) I was able to successfully start the OS from system rescue CD. I'd like to ...
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make: i686-linux-gcc: Command not found

I am using Ubuntu-11.10 amd64 and trying to cross-compile a linux-2.6.38.8 kernel for a 32-bit target.I tried make CROSS_COMPILE=i686-linux- ARCH=i386 But I got error make: i686-linux-gcc: ...
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Unable to install Atheros AR8161 Ethernet controller driver for centOS 6

I've installed CentOS 6.3. However, eth0 does not show up on ifconfig. So I figured out that I need to install alx Ethernet driver from here. Since my internet is not working, as ethernet drivers are ...
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How is the kernel loaded?

I am trying to understand the Linux boot process, and after reading quite some amount of documentation there is one point that I still can't seem to understand. So the basicis is BIOS -> Grub MBR -> ...
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The UEFI & SecureBoot impact, how severe?

I'm planning to buy a new laptop in the coming days, and I'm quite impressed with new, cool Ultrabooks. As a long-time GNU/Linux user, I'll of course install a distro of my choice on it. Chances are ...
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How to run Different congestion control algorithms in FEDORA 17 ..?

Earlier versions of Fedora has different loadable kernel modules which includes diffrent congestion control algorithms etc at (/lib/modules/"kernel-name"/kernel/ipv4).These are present in the form of ...
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What would be the best way to work around this glibc problem?

I administer a Gentoo Hardened box that uses file capabilities to eliminate most of the need for setuid-root binaries (e.g. /bin/ping has CAP_NET_RAW, etc). Infact, the only binary I have left is ...
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No make target “uImage” with Buildroot 2013.05

After enabling Linux Kernel option and setting the Kernel binary format to uImage, I always get the following error: make[1]: * No rule to make target `uImage'. Stop. My buildroot configuration is ...
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Linux Operating system recovery after abnormal termination

How does the operating system (Linux) while rebooting checks whether abnormal termination happened during last shutdown and then does the file system consistent checks etc if required ?