Everything about UNIX kernels: development, configuration, compilation, design, etc.

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Debugging Linux Kernel with QEMU

I was trying to study the debugging of kernel using QEMU. I tried initially and failed due to the fact that there was no virtual file system. The answers to this post suggests that there should be a ...
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Kernel panic after Gentoo install — cannot open root device

I have a Debian system on /dev/sda1 (/) and /dev/sda2 (extended, /dev/sda5 is /home, /dev/sda6 is swap). I want to install Gentoo in parallel, so I shrinked sda2 and created /dev/sda3, in which I ...
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91 views

“rcu_preempt detected stalls on CPUs / tasks” message appears to continue

My board continues to display the message below. The terminal does not have any input. What is it with the following message, which I know? (T, g, c, q ...) What is the cause of this phenomenon? ...
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In Debian Jessie, make allnoconfig and make allyesconfig generate the same .config file

In debian jessie, I've installed the linux source with: sudo apt-get install linux-source I obtain a file /usr/src/linux-source-3.16.tar.xz, I copy it under my home directory, change the ownership ...
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Scaling issues of i7 3520M with intel_pstate module on Kernel 3.10.0

Few days ago I updated my openSUSE 12.3 system from Kernel 3.9.8-1.gf3348a8-desktop to 3.10.0-1.g3dcd746-desktop and since then, turbo mode of my i7 3520M is enabled by default and it does not ...
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Shared IRQs not operating properly

I'm having problems trying to make use of four out of six serial ports on my motherboard. The situation is: I have 6 serial ports available - ttyS0 to ttyS5 - of which 0 is a RS232 port on the edge ...
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91 views

No /dev/mmcblk0 during boot

I am trying to install CentOS-6 on an eMMC drive. Since the supported 2.6.xx kernel from CentOS-6 doesn't support mmc, I compiled a newer kernel (4.2.6) which has updated mmc drivers. I tried booting ...
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What is the information present inside a kernel core dump

I am running CentOS 6. The system got a Kernel Panic and rebooted. I have enabled coredump generation, hence it generated a Kernel Core Dump of Size 300MB. What is the information that got ...
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FreeBSD: How can I install kernel sources for 10.2-STABLE version?

Lots of articles and posts on internet tell how to install the kernel sources for FreeBSD x-RELEASE versions, but none of them for X-STABLE. For example, my FreeBSD version is 10.2-STABLE. How can ...
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Arch linux kernel upgrade from repositories

About two months ago I build a kernel (4.2.6-ARCH) from source according to this page, this is my current kernel version, the problem comes when I try to upgrade from the repositories, actually I did ...
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CentOS update from 7.1 to 7.2 with 2.6 OpenVZ kernel?

We are using CentOS 7.1: $ cat /etc/redhat-release CentOS Linux release 7.1.1503 (Core) We deferred the 7.2 upgrade. It looks like it did not cause any problems so we are planning an upgrade. The ...
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How does Linux kernel compare to microkernel architectures?

I read once that one advantage of a microkernel architecture is that you can stop/start essential services like networking and filesystems, without needing to restart the whole system. But considering ...
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prevent from writing to a large continuous section of virtual memory [closed]

How can an operating system kernel efficiently prevent a user process from writing to a large continuous section of virtual memory?
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Which Debian kernel should I install?

I've started installing Debian testing on amd64 and I've come to a screen asking me to install a kernel. It gives me a choice between linux-image-3.16-2-amd64, linux-image-amd64, and none. What is ...
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Identifying disk drives during RHEL/CentOS/Fedora Installation

What steps are followed in order to identify a connected disk drive during Linux installation ? I am interested RHEL/CentOS/Fedora procedures. Is it entirely depends on the Kernel package and drivers ...
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What is the difference between kernel drivers and kernel modules?

When I do a lspci -k on my Kubuntu with a 3.2.0-29-generic kernel I can see something like this: 01:00.0 VGA compatible controller: NVIDIA Corporation G86 [Quadro NVS 290] (rev a1) Subsystem: ...
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Unable to setup TL-WN722N or Unable to install/complete headers

I would like to set up the tl-wn722b WLAN Adapter. I have a Kali Linux version for a Raspberry Pi. I tried to follow this tutorial: ...
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How does GUI works different from the shell CLI?

For example if I want to remove a file I would write rm command in my shell CLI. But when I delete a file using GUI how does the process works ? For shell it would find the filesystem for rm program ...
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How do I read from /proc/$pid/mem under Linux?

The Linux proc(5) man page tells me that /proc/$pid/mem “can be used to access the pages of a process's memory”. But a straightforward attempt to use it only gives me $ cat /proc/$$/mem ...
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38 views

Copy the Linux kernel config file to another distribution

I am installing new Linux distro (gentoo) and I want to copy the linux kernel config I have here in the linux mint live USB to the Gentoo system. The way Mint has the kernel config file is ...
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41 views

change size of devtmpfs /dev/

My new kernel has CONFIG_DEVTMPFS enabled, and thus my /dev is mounted as devtmpfs. My old kernel was not using CONFIG_DEVTMPFS, and /dev used to be mounted as plain tmpfs. Now I have noticed, the ...
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Problem with xv6 on qemu

I was doing the assignment on this link --> http://zoo.cs.yale.edu/classes/cs422/2013/lec/l2-hw After running make qemu the assignment document says A separate window should appear ...
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89 views

Different Debian versions from two different commands

This might be silly, but I'm new to Linux. I wanted to check my current Debian version so I typed uname -a and it gave me some stuff including Debian 3.2.73. But Then I found this command cat ...
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Setting up HDMI output from Linux console

I am currently running Debian Wheezy on a HP Microserver N54L with an AMD Radeon 5450 video card. I would like to be able to play audio from the console through the HDMI port of my video card and ...
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Error while building Linux kernel for versatile board

I'm trying to build the 2.6.32.69 version of Linux Kernel for versatile board but I got this error during the build step init/mounts.o: In function `tty_port_users': ...
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726 views

How can Linux 4.2.5 boot on a Skylake CPU when they are supported from 4.3+

I bought a Dell XPS 13 2016 with a i7-6500u (SkyLake). This notebook is not officially linux-supported but I found a few articles on how to get it up and running. But I cannot find an answer to this ...
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33 views

DKMS modules never installed properly on kernel upgrade

I have multiple DKMS modules installed on my system, some of them mine, and some of them belonging to pretty major maintained packages such as Oracle's VirtualBox 5. What I've found is that on every ...
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705 views

TUN/TAP Will not load

I have an OpenVZ server but can't seem to get the tun/tap module to load. I ran modprode tun on the hostnode but when I go under the VM I get: Tue Sep 24 03:08:36 2013 Note: Cannot open TUN/TAP dev ...
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25 views

Change the parameters a kernel module loads with

When I plug in an SD card in Ubuntu, the module mmc_block loads with the value of mmcblk.perdev_minors set to 8. I am pretty sure this is the default value coded into the module. What file might I ...
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88 views

How the terminal can run programs and show its output? [closed]

I'm slowly creating a mental model of how linux works, and I've tried to simplify the most, my model of how linux works. Let's assume that the kernel boots and inits the only software it's gonna run: ...
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453 views

Xorg on skylake graphics hangs

I've bought msi gs40 that has intel i7 6700HQ which means integrated graphics hd 530. After a day of struggling I was able to start xorg with HD530. For this I addes i915 to initramfs and ...
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My SLES 11 uses 6 GB RAM while nothing is running. How can I find out what is needing it? [closed]

Can anybody tell me what is consuming that much memory on my SLES 11 SP3 server? I suspect a serious bug in the kernel that it does not release memory allocated by an application once it quits. This ...
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vmlinuz damaged

Hello everyone I am new here. I recently purchased Ubuntu 14.04 LTS DVD from a retailer store. Then I burned the iso into my pendrive and configured the file isolinux.cfg. The file was alright. ...
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180 views

Using DKMS, to automatically patch and install kernel on update

I have a system that needs patching a file in kernel to work properly. The system is running Ubuntu 14.04. The patch patches a file in drivers/hwmon. So after every kernel update I need to download ...
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Using dkms to patch kernel

I need to apply a kernel patch(https://lkml.org/lkml/2015/3/31/929) to get my touch-pad working properly. I am thinking that I should be using dkms, to do this. Most of the stuff I am reading is about ...
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new kernel compile - error on bootup - Could not find overlay

I was compiling the kernel using slackware-current, the latest version of the kernel, 4.3.3, also tried 4.4-rc5, and ran into this error on bootup Could not find overlay #6 ### dt-test ### of ...
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870 views

buildroot/busybox: launch bootchartd on startup

I built a custom linux image using buildroot and busybox. To speed up the boot process I'd like to use bootchartd (built-in version of busybox) to profile the process. However bootchartd is not ...
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43 views

Create serial console on plug in USB serial device

I have a CentOS 7 headless system with no serial ports. I sometimes want to access the server using a serial cable, so I plug in a USB serial cable (to my laptop's serial port) but I can't get a ...
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1answer
819 views

Debian: GPG cannot fetch Linux Kernel key

I am in the process of recompiling the kernel on Debian. Following the instructions on kernel.org, the first step is to verify the signature. But GPG complains that it cannot find the public key: # ...
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1answer
116 views

check-config errors on Linux 3.19.0 kernel, configured under Ubuntu 15.04 x86-64

I'm new to configuring Linux kernels, and am receiving the following errors when running config-check: check-config: /tmp/tmp.tnqExc0fHn/CONFIGS/amd64-config.flavour.generic: loading config ...
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1answer
46 views

how do i know if the kernel changed

i have a scenario where i need to recompile my display drivers after kernel updates. i'm trying to shome how automate it with bash scripts during boot time. so i need some sort of a way to know that ...
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How can I upgrade my debian kernel to 4.3.2?

I am experiencing wireless stability issues and I'd like to upgrade my debian kernel So I'd like to know how can I upgrade my current kernel to the latest stable kernel on kernel.org ? (4.3.2)
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186 views

How to compile a third party driver into the kernel?

I am using Linux Mint 17.2 on Toshiba c640. As my LAN driver is no more functional, I am using a USB to LAN converter which was provided with some driver installation files. Every time i want to use ...
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What's the difference of dmesg output and /var/log/messages?

AFAIK dmesg shows information about kernel and kernel modules, and /var/log/messages also shows information produced by kernel and modules. So what's the difference? Does /var/log/messages ⊂ output ...
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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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How to add more /dev/loop* devices on Fedora 19

How to add more /dev/loop* devices on Fedora 19? I do: # uname -r 3.11.2-201.fc19.x86_64 # lsmod |grep loop # ls /dev/loop* /dev/loop0 /dev/loop1 /dev/loop2 /dev/loop3 /dev/loop4 /dev/loop5 ...
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How to compile the C compiler from scratch, then compile Unix/Linux from scratch

Let's say I work for a large services organisation outside the US/UK. We use UNIX and Linux servers extensively. Reading through this article it mentions that it would be easy to insert a backdoor ...
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1answer
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How does the kernel prevent a malicious program from reading all of physical RAM?

If I write a program that tries to read memory at every possible address, and I run it on a "full" Unix, it will not be able to access all of the physical RAM. But how does the operating system ...
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1answer
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How can Wireshark see packets dropped by iptables?

I recently installed my hard drive in a new computer and after some fiddling around I noticed my iptables rules were dropping DNS responses for some reason, turns out they were configured to allow ...
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building kernel cause dependency cycle error

I was trying to compile latest kernel with some edits. while doing sudo make modules_install INSTALL virt/lib/irqbypass.ko DEPMOD 4.4.0-rc1+ depmod: WARNING: found 2 modules in dependency ...