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

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Spawn multiple dirty page flusher threads per device

In earlier 2.6.X kernels, pdflush was used and it would spawn more pdflush threads if all current pdflush threads were busy for a second (read from The Linux Page Cache and pdflush). Since the ...
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93 views

Is a page with “PROT_NONE bit set” eligible for swapping?

From the following link: Page Table Management - kernel.org, I understood that the bits PROT_NONE and PRESENT can be used to let the OS know that a page is protected but is resident in memory. I am ...
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132 views

How does the kernel store the virtual memory area?

I am trying to understand do_page_fault in fault.c (x86 architecture). I came across the method access_error where we compare the error code to the vm flags. As per my understanding, we are checking ...
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100 views

Using Linux kernel config file from version to version

I have currently Linux Kernel 2.6, which works for my hardware. Now I want to compile Linux kernel 3.2 for the same hardware. Can I use the same .config of 2.6 directly for v3.2? Is there any ...
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638 views

Linux kernel manual build: resulting binary is 10 times larger than precompiled binaries

I'm using Linux Mint 13 MATE 32bit, I'm trying to build the kernel (primarily for experience and for fun). For now, I like to build it with the same configuration as precompiled kernel, so firstly ...
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70 views

How do you patch a kernel? [duplicate]

I got diff text from lkml how do I patch it into a kernel source? I am very new to compiling kernels, and I couldn't find decent sources online I am using debian if it is relevant
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955 views

installing grub and a working kernel over an old and broken debian system

I have an old debian system, which I always have been able to upgrade over the years. I had installed an old kernel, compiled by me from sources. After my last dist-upgrade (using testing ...
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68 views

Questions about kernel releases

Right now there are about 7 (or more) kernels maintained by the Linux Foundation. I was wondering if you could clarify my doubts and answer my questions: Isn't the next kernel's release maintaining ...
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443 views

Loginuid, should be allowed to change or not (mutable or not)?

I am trying to configure the linux kernel. I was confused by Make audit loginuid immutable (AUDIT_LOGINUID_IMMUTABLE) [N/y/?]. The help says: +config AUDIT_LOGINUID_IMMUTABLE + bool "Make ...
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1k views

File handles and filenames

I read this post. Are file descriptors the same as file handle? While trying to configure the linux kernel, it asks open by fhandle syscalls (FHANDLE) [Y/n/?]. Why is this option provided? Does ...
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87 views

How do I know what decompression algorithms are compiled-in into the linux kernel?

If /proc/config.gz is unavailable, how do I know what decompression algorithms the running kernel is capable of using on a compressed cpio initramfs? Is the gzip algorithm always available, even when ...
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229 views

How do I find out what filesystem drivers are compiled-in into the linux kernel?

On a running linux system, what is a portable (among linux distributions) way to find out what filesystems the current kernel has compiled-in (not through modules) support for? Consider for example ...
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388 views

Enable BFQ in Fedora

I am running Fedora with the stock kernel and I'd like to enable the BFQ disk I/O scheduler, and ideally BFS. I have built my own kernel and that works, though it is a royal pain dealing with the ...
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2answers
5k 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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48 views

Kernel bisect: when a patch is failing for a reason other than original bisect purpose, what do you do? [closed]

Let's say you're trying to find the cause of a bug between 3.11.0 and 3.12.0. The bug is really difficult to catch, because it may or may not manifest itself over several days of regular workload ...
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1answer
2k views

aircrack-ng shows negative channel

On many Linux distributions, be it BackTrack, Kali, BackBox, Ubuntu, Mint, etc., whenever I use anything from the aircrack-ng suite my wireless card is shown as channel -1. This problem has been ...
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1answer
108 views

How do I compile source into the kernel?

I want to add and compile my custom application code into my kernel. How should I add my .c and .o files into my kernel 'bin' directory and compile them? I made a hello.c and hello.o file and I want ...
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1answer
2k views

In what sense does SATA “talk” SCSI? How much is shared between SCSI and ATA?

This is nothing new to me at least, that SATA actually "talks" SCSI, hence why these SATA devices show up as SCSI devices in Linux. A related question has been asked before, e.g. Why do my SATA ...
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1answer
366 views

File backed, locked shared memory and disk interaction

Varnish, a HTTP accelerator, uses a ~80MB file backed SHM log that is mlock()ed into memory. The Varnish docs recommend to store the file on tmpfs to avoid unnecessary disk access. However if the ...
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2k views

Linux 2.6.36.4, GCC 4.7.2, getting lots of “variable set but not used” warnings

I am trying to compile the Linux kernel 2.6.36.4 on Linux Mint 14 running a 3.5 kernel by default. Using gcc version 4.7.2. Tried googling it, but didn't quite work out. The warning is: warning: ...
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234 views

SLES 10 SP4 - how to get specific kernel source?

I want to look at the kernel source for some specific kernel versions on SLES 10 SP4. I don't want to see just the Linux kernel source, but the one SLES is actually running. Suppose I wanted to get ...
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225 views

Virtual kernel memory layout in dmesg linux kernel 2.6.31

I'm working on a embedded linux project for ARM architecture, kernel version is 2.6.31.12-rt21. In dmesg, I cannot see the virtual kernel memory layout like this: virtual kernel memory layout: ...
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154 views

inotify does not work with linux kernel 3.4.11

I have a Linux running with kernel 3.4.11. I tried to run inotify-tools, but it does not work (in fact it does not detect the file changes). I checked the .config file of Linux kernel and I found ...
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519 views

Linux kernel dropping custom keyboard scan codes

I have a vintage IBM 122 key model M keyboard that I am adapting for use on a modern computer. I am using a Teensy 2.0 to do the encoding and to handle the USB side of things. I borrowed the firmware ...
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353 views

ncurses-devel problems in SuSE Linux Enterprise Desktop 11

Searching on the WEB, I found this tutorial (the only one that has convinced me) for installing a new kernel and I followed the steps provided. But, I got these problems: In the first step I tried ...
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kernel config with strange dependancies

I am trying to build the Android Linux kernel from source following this README. The instructions very clearly state: 1.1 Required enabled config options: After building a standard defconfig, ...
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510 views

How is 32bit Linux virtual memory structured in relation to PCIe Base Address Registers

I'm working on a Linux system (32 bit, 4GB RAM) and found some contradictory information about memory addressing in Linux. Am I right with this: Only virtual memory has the differentiation between ...
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1answer
1k views

DisplayPort and Intel HD cause GPU hangs

My system has problems with the displayport connection. This is indicated by several problems that, at the first glance, do not have anything in common. The reason why I claim DP for beeing the cause, ...
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266 views

Linux memory usage?

We have 1TB of memory on a server which hosts an SAP application. When the app is running the memory usage shown in top is around 700GB. When the app is stopped the memory usage shown in top comes ...
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2k views

Who is responsible for the Linux kernel?

As of today, there are many Linux distributions like Ubuntu, Fedora, Gentoo, Mint, Debian, etc. These distributions update at different cycles. Ubuntu seems to update its kernel weekly or monthly, ...
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235 views

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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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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170 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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1answer
283 views

I/O schedulers for normal harddisks

For me figuring out what is the best choice for I/O scheduler in kernel was a challenge. First I learned that it is subjective then it depends upon the filesystem you use. I know you should use ...
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1answer
155 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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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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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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527 views

How do I make strace “decode” AF_NETLINK communication as with ioctl?

strace usually "deciphers" ioctl calls, showing what they mean, even resolving network interface names and so on. But the same operation performed using AF_NETLINK stays opaque in strace. How can I ...
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How to tell whether RAM ECC is working?

I'm planning on getting some ECC RAM to replace the non-ECC RAM I currently have installed on my Asus M5A97 Pro motherboard (AMD 970 chipset, FX-6100 CPU). After I install the RAM, how do I tell ...
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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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691 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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1answer
586 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
56 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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1answer
3k 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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525 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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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
432 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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2k 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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178 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 ...