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

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I need to perform a kernel upgrade on a live system. Best practices?

Steps taken so far: apt-cache search linux-image* apt-get install linux-image-... I was now thinking of rebooting and selecting the new kernel when it appears on the GRUB menu, however: Is it ...
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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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virtualbox can not create new virtual machine

I'm try to make a new virtual machine but virtualbox have this error in end step : Failed to create a new session. Callee RC: NS_ERROR_FACTORY_NOT_REGISTERED (0x80040154) and in terminal this shwn ...
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extract Embedded initramfs

I have a kernel in which one initramfs is embedded. I want to extract it. I got the output x86 boot sector when I do file bzImage I have System.map file for this kernel image. Is there any way to ...
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Continuety of driver support in linux kernel

I am an embedded GNU/Linux learner. I understand with the new Kernel, driver support for most added hardware is coming through Device Tree Structure (DTS). But I have found out that there are still ...
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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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Benefiting of sched_autogroup_enabled on the desktop

I am running a 2.6.37 kernel with sched_autogroup_enabled set to 1. I am not certain that I am seeing the benefits of this patch since: I am launching my applications from the desktop; applications ...
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What are the concepts of “kernel ring buffer”, “user level”, “log level”?

I often saw the words "kernel ring buffer", "user level", "log level" and some other words appear together. e.g. /var/log/dmesg Contains kernel ring buffer information. /var/log/kern.log ...
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Kernel booting stops right after “Uncompressing Linux…”

I'm trying to bring up an ARM-based board. I've got U-Boot working but can't seem to get the kernel to load. Most of the time it only goes as far as: Starting kernel ... Uncompressing Linux... A ...
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Set default kernel in GRUB

How can I pick which kernel GRUB2 should load by default? I recently installed a the linux realtime kernel and now it loads by default. I'd like to load the regular one by default. So far I only ...
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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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Are “kernel mode” and “user mode” hardware features or software features?

I read that there are two modes called “kernel mode” and “user mode” to handle execution of processes. (Understanding the Linux Kernel, 3rd Edition.) Is that a hardware switch (kernel/user) that is ...
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Making Linux read swap back into memory

The Linux kernel swaps out most pages from memory when I run an application that uses most of the 16GB of physical memory. After the application finishes every action (typing commands, switching ...
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How to disable core dump generation in Centos (cPanel Server)?

I want to disable core dump generation, How can I disable it ? One of the website keeps generating core dumps every second and eats up all the disk space. OS Details: CentOs cPanel Server ...
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VMware and kernel 4.0

I'm trying to install VMware in Elementary OS freya updated with kernel 4.0 but it doesn't start. The error suggests incompatibility with kernel 4.0. How can I solve this?
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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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What are the deb files for installing a kernel for?

When installing a kernel in Ubuntu(e.g. http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.0-vivid/), what are the files for respectively: linux-headers-4.0.0-xxx_all.deb ...
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busybox initramfs loop mount

I'm trying to loop mount my root filesystem (a loop file) within a busybox initramfs. I try to run the command: mount /rootfs.raw /root ... which works on my Ubuntu laptop, however, I simply get ...
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How to test modified FreeBSD source code?

I am trying to modify the default congestion control algorithm in FreeBSD (NewReno) by creating a copy of the source file (cc_newreno.c, located in /usr/src/sys/netinet/cc) called cc_newreno_mod.c and ...
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How does ath9k introduce itself to mac80211?

My question is about Linux kernel and ath9k wireless driver: How does ath9k announce itself to the mac80211? How come the mac80211 knows how to configure ath9k? Thanks in advance
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why can't we install application compiled for Ubuntu, on Linux mint, or some other distros with same kernel?

When i try to download some applications like VLC, it shows in download options, various Operating systems which includes Linux mint, Ubuntu etc. Though Linux mint's kernel is from Ubuntu, still they ...
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is THP good or bad for MySQL Server?

Linux kernel new feature called Transparent Huge Pages (THP) which is by default enabled on CentOS 6.x and above OS. Is THP good for MySQL DB machine? I am trying following to disabled THP but seems ...
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quick question about kernel modules [migrated]

I'm very familier with linux (been using it for 2 years, no windows for 1 1/2 years), and i'm finally digging deeper into kernel programming and I'm working a project. So my questions: Will a kernel ...
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Is there any Syscall table just like Interrupt Table?

Are the system calls like fork(), exit() saved in some kind of function pointer table , just like the Interrupt Descriptor Table ? where does my OS go when I call my fork() or exit() ? I guess this ...
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Kernel Firmware for Radeon

I'm building LFS. I was trying to enable Ati radeon drivers in the kernel, but it didn't seem to work, so I did a little Googling and found that the there is something called firmware which the kernel ...
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Debian wheezy, 3.19, problem keyboard and mouse on dekstop environment

I am running Debian Wheezy on a BananaPi. I just compiled the kernel and the keyboard was working in terminal(if it's called that way). However, after I installed a dekstop interface using "apt-get ...
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480 views

Wireless constantly reconnecting on Ideapad running Arch

I just bought a new laptop, a Lenovo IdeaPad U330 touch, and after some struggle (with the Secure Boot stupidity) I have managed to install Arch Linux. I have configured my system, installed all the ...
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How to get ondemand governor on fedora

In Ubuntu 13.10 on my (Dual Core i5 Lenovo G570) laptop, I recently discovered the wonders of indicator-cpufreq, so I can extend my battery life dramatically by setting it to 'ondemand' or 'powersave' ...
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kernel compilation in ubuntu, reboot msg “gave up waiting for root device”

I was trying to compile Linux kernel from source file i.e. 3.19.3 kernel version I ran the following commands for compilation first I extracted tar -xvf linux-3.19.3.tar.xz changed to its ...
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No sound with audio jack

I am using a Debian wheezy on Netbook eeepc 1001px After last kernel update When I plug the audio jack, I can here the electric charge but no sound when I remove it the internal speaker works ...
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Problems with file system

I created a partition with EXT4 file system and when I'm writing in this partition frequently the Kernel return the following error: Jan 01 01:17:54 infobuffer360 kernel: r7:c0561280 Jan 01 01:17:54 ...
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How to change the kernel max PID number? [duplicate]

The default PID max number is 32768. To get this information type: cat /proc/sys/kernel/pid_max 32768 or sysctl kernel.pid_max kernel.pid_max = 32768 Now, I want to change this number... but I ...
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What is the difference between reboot , init 6 and shutdown -r now?

I just want to know difference between in reboot init 6 shutdown -r now and which is the safest and the best?
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Is USB-to-USB data transfer between two Linux OSes possible?

I want to create a USB-to-USB data transfer system in Linux (preferably Ubuntu). For this I want to use no external hardware or switch (except this cable). It's going to be like mounting a USB drive ...
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what does mount -o remount,ro / actually do (under the hood)

To remount a mounted filesystem to read-only, I can use following command: mount -o remount,ro /foo This is used for example in the shutdown sequence, where root filesystem (/) is remounted ...
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How to assign USB driver to device

This question is two-fold: First, how do you manually detach a driver from a USB device and attach a different one? For example, I have a device that when connected automatically uses the ...
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Is that safe to use kfifo (not a _spinlock flavour) in fiq/nmi handlers? [migrated]

Basically need to pass variable-size records to and from FIQ handler (ARM platform). During any get/put operation on kfifo (on the user-space/kernel side only) I am going to disable all IRQs and ...
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How do you empty the buffers and cache on a Linux system?

Prior to doing some benchmarking work how would one free up the memory (RAM) that the Linux Kernel is consuming for its buffers and cache?
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Increase multipathed filesystem journaling threads?

We have some hardware which is utilizing multipath to speak to backend storage. A situation has been observed which some are attributing to too few journaling threads being allocated by the kernel. ...
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What are unimplemented system calls?

I was revising Linux system calls. I found that a few calls are unimplemented system calls. For example: afs_syscall. I don't understand why they are included in man pages if they are not yet ...
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Adding a new System call to Linux 3.2.x with a loadable kernel module [closed]

I want to add a particular new system call in the linux kernel 3.2.x but as a loadable kernel module (as I don't want to recompile the kernel again and again) I read through many posts on internet ...
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How to install/compile module in Debian without using Full Kernel, only by using the already installed kernel headers

I am a newbie in Linux/Debian and searched the internet for a few days but didn't managed to find any good tutorial. Can someone explain step by step how to install a module on a kernel with headers ...
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Kernel Panic dumps no log files

I was playing a game on Steam and all a sudden I got a kernel panic, I manually shutdown the computer and booted back into Linux Mint 17.1 (Cinnamon) 64-bit, and went to go check through my log files ...
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GDM UI screen update is jittery with Kernel 3.4 with N2600 ATOM processor

This is in continuation to my earlier post : Upgrading guidance for Cedarview driver in Debian 6 - 2.6.32 I recently updated my kernel from 2.6 to 3.4 (Just for making N2600 chipset detect my ...
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running kernel on QEMU

I face this message: Failed to execute /initKernel panic - not syncing: no init found. Try passing init=option to kernel. I am using this command line: qemu-system-x86_64 -hda disk.img -kernel ...
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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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Xen Kernel - SCSI_WAIT_SCAN Module

We've recently deployed a HP ProLiant DL180 Gen9 with 12 x Intel 530 SSD Drives. The system is running RAID-10 on top of HP Smart Array P840. Our aim was to use Xen on this server. However, when the ...
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Linux kernel version suffix + CONFIG_LOCALVERSION

On system start up I currently see Linux 4.0.0-rc6yy and 4.0.0-rc6yy.old from the bootloader menu. I'm not certain where they came from. I suspect "yy" is arbitrary but can someone explain the ".old" ...
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Why system call hooking produces different result everytime in Linux/Android 2.6.29?

I have implemented system call hooking for Android 2.6.29 kernel through a LKM module. I am tracing down one Android app for system calls. But interestingly, it returns different results every time I ...
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Which bus drivers to include when compiling freeBSD kernel?

I'm trying to compile a FreeBSD kernel and make it as light as possible. I'm struggling with the configurations on the bus, especially the SCSI Controllers part. there are many modules e.g: ahc, ahd , ...