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

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psmouse sync issues!

I have Compaq CQ61-420US (64-bit AMD) laptop with Synaptics touchpad checked using $ egrep -i 'synap' /proc/bus/input/devices N: Name="SynPS/2 Synaptics TouchPad" But recently after Arch Linux ...
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2answers
787 views

Asus X101H - Touchpad not recognized (want to disable while typing)

I have been struggling with this issue for a while and have done an exhaustive search for answers here and elsewhere before posting this question. On my Asus X101H, the touchpad is not recognized as ...
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1answer
43 views

crypto kernel module not available on Raspberry pi 2 (linux 3.18.11)

I'm trying to use dm-crypt on my Raspberry Pi 2 with Raspbian (debian) to open a trueCrypt volume, but i get Required kernel crypto interface not available. Ensure you have algif_skcipher kernel ...
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Having problems with negative monitor channel, intimidated!

When I try this command: aireplay-ng -1 0 mon0 -a xx:xx:xx:xx:xx:xx I get this output: No source MAC (-h) specified. Using the device MAC (xx:xx:xx:xx:xx:xx) 17:51:23 Waiting for beacon frame ...
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How is a process state updated to blocked state (TASK_INTERRUPTABLE)? [migrated]

When a process is waiting for IO, how is the task state updated to TASK_INTERRUPTABLE (that is, blocked)? Imagine this case, a process issues an IO request to a block device. According to my ...
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2answers
2k views

How to know if a network interface is tap, tun, bridge or physical?

As far as i know, there are 4 main types of network interfaces in linux: tun, tap, bridge and physical. When i'm doing sys admin on machines running KVM, i usually come accross tap, bridge and ...
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Kernel problem after editing filesystem.squashfs

I use Kali Live linux (which is based on Debian), today I tried to edit filesystem.squashfs file which is located at /live/filesystem.squashfs using squashfs-tools. First I extracted this file using ...
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1answer
43 views

Relationship between IO scheduler and cpu/process scheduler?

The concepts of IO scheduler and CPU scheduler confuse me. Below are my understanding: Linux uses CFS scheduler + nice values by default to schedule processes. Each process has an IO queue. There ...
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1answer
144 views

Which file in /proc gets read by the kernel during the boot up process?

Which file in /proc gets read by the kernel during the boot up process? This was a question on my LPIC 101 test that I think I might have answered wrong. I searched on google and some other places but ...
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2answers
338 views

How to measure PCI-Express bus usage?

I'm looking for a way to find out if PCIe bus is the bottleneck or not. It's not a problem to measure how much bytes was transferred through any particular NIC: Is there a way to find how much ...
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shm.h header file not found in Linux 3.13.3 [migrated]

I am new to for Linux. I have downloaded Linux 3.13.3 and I am trying to make a system call for shared memory. I have created a "hello world" system call and it runs perfectly. When I compile my ...
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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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1answer
64 views

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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1answer
50 views

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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2answers
353 views

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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1answer
2k views

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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2answers
72 views

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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1answer
3k views

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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2answers
75 views

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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4answers
781 views

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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1answer
49 views

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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2answers
72 views

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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1answer
48 views

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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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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2answers
38 views

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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179 views

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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1answer
1k views

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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2answers
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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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1answer
504 views

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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4answers
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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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1answer
187 views

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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1answer
14k views

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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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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1answer
108 views

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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1answer
58 views

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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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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2answers
33 views

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 , ...
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1answer
65 views

Error: you do not appear to have the sources for the 2.6.32-042stab102.9 kernel installed

I've just bought a new VPS with Cent OS 6.6 installed. I'm attempting to install Asterisk 11 on this VPS via command line remotely. I've used the directions here however I get this error: you do not ...
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2answers
253 views

ubuntu Kernel panic while installing CentOS 7 in VirtualBox

I have a laptop with Xubuntu desktop 14.10 , and I installed VirtualBox and updated it to the latest version . I'm trying to install CentOS 7 (source downloaded from the official site) as a VM, ...
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80 views

U-Boot Bootup error

I'm running a Debian Linux on a Cubietruck, running off a SD card. When I power on, I get the following error: Booting kernel from Legacy Image at 46000000 ... ...
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1answer
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Is the PTTY inside the Kernel or Userspace?

I read, that drivers are a way to expand the Kernels abilities to communicate with hardware devices, since there are so many and will be even more the Kernel has to be expandable. In order to ...