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

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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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8answers
10k views

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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2answers
29 views

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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1answer
2k views

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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5answers
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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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0answers
70 views

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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36 views

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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4answers
61k views

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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2answers
84 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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1answer
132 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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38 views

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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1answer
106 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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0answers
146 views

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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1answer
1k 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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1answer
77 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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1answer
811 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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1answer
63 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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1answer
172 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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0answers
718 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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0answers
35 views

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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0answers
38 views

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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1answer
212 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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1answer
43 views

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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2answers
936 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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1answer
61 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
888 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
179 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
50 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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0answers
112 views

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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1answer
254 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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4answers
59k views

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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4answers
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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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3answers
7k views

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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4answers
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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 ...
5
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1answer
147 views

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
87 views

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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1answer
151 views

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 ...
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2answers
115 views

Install Debian kernel header files 3.4.90+ via terminal for ARMHF

I am trying to install the kernel header files on Debian via the terminal, but it does not seem to exist in apt-get. The reason I need the kernel header files is because I need to install WiFi ...
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0answers
50 views

QT application doesn't receive udp broadcast since linux kernel 3.13.0-70

I'm developing a QT application on Ubuntu and suddenly had problems because QT app doesn't receive UDP broadcast messages. They are visible in Wireshark on that machine, but never received in QT. ...
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0answers
33 views

Bridging two interfaces with iproute2 doesn't work

I'm trying to create a bridge between eth0 and eth1 with iproute2, but there's always the error: RTNETLINK answers: Operation not supported when I use the command:ip link add name br0 type bridge. ...
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1answer
47 views

After my system crashed and I run crash, but I get the following error: not a supported file format

My system crashed and even though I haven't been able to know what caused the crash after going through the usual logs: messages, dmesg, secure, etc. There's nothing valuable I have seen on them so I ...
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5answers
46k views

What are high memory and low memory on Linux?

I'm interested in the difference between Highmem and Lowmem: Why is there such a differentiation? What do we gain by doing so? What features does each have?
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1answer
6k views

Real time processes scheduling in Linux

I have been learning some scheduling concepts. Currently my understanding so far is as below. There are real time processes and non real time processes. Non real time processes can have nice values ...
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0answers
203 views

ip link add gives me an error that it's not supported

I would like to set up a bridge with iproute2 like this: Adding bridge : ip link add name br0 type bridge Bringing bridge UP : ip link set dev br0 up Adding interface to bridge : ip link set dev eth1 ...
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0answers
46 views

Ubuntu DMA Auto Activate Optimization Flag

I have two NAS devices, which differ in architecture. They are connected to the same SATA disks and one of them shows better read and write performances. Okay, there could be many reasons for such ...
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1answer
27k views

What is kernel ip forwarding?

I have seen on many blogs, using this command to enable IP forwarding while using many network security/sniffing tools on linux echo 1 > /proc/sys/net/ipv4/ip_forward Can anyone explain me in ...
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0answers
28 views

Assign virtual core number to specific real core

Is there any way to assign ''linux core numbers'' to specific real cores? I'm working with an asymmetric architecture, so not all cores are the same, and I want to assign specific cores number to ...
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5answers
17k views

Why is kworker consuming so many resources on Linux 3.0.0-12-server?

Last Friday I upgraded my Ubuntu server to 11.10, which now runs with a 3.0.0-12-server kernel. Since then the overall performance has dropped dramatically. Before the upgrade the system load was ...
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2answers
3k views

Automatic kernel configuration tool

Is there any developed automatic linux kernel configuration tool? I have found a method of make localmodconfig, but it is certainly very limited. I have searched the web but unfortunately have not ...