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

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Why does my process take too long to die?

Basically I'm using Linux 2.6.34 on PowerPC (Freescale e500mc). I have a process (a kind of Virtual Machine that was developed in-house) that uses about 2.25 G of mlocked VM. When I kill it, I notice ...
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23 views

How to determine if the kernel sources are installed?

I just bought a USB 3.0 Gigabit ethernet adapter. It uses an ASIX ax88179_178a driver. I need to build the driver and the readme says: ...you need the Linux kernel sources installed on the build ...
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8 views

How to catch my bluetooth service events

I have usb bluetooth device which is using btusb 0.6 module (driver). The thing is I am interested to know is: how is the systemctl start bluetooth.service event invoked? I was looking info about ...
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13 views

How does rootfs.ext3 image file work?

I have a FriendlyARM mini6410 device and I have just hardly make it boot from sdcard. Now my sdcard uses "u-boot for mini" (u-boot.bin), "linux2.6.38 kernel" (zImage) and "rootfs qtopia fs" ...
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78 views

What is a Kernel Routine ?

In another answer I met a short overview of the sections of the man pages: commands for $-User system call, that means evoking a function from the Kernel library call, that means evoking a function ...
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1answer
23 views

4G modem on an embedded 2.6.32.9 kernel on a Parrot AR Drone 2.0

I am attempting to compile support for a Huawei E3276 usb LTE modem for an embedded Linux/BusyBox installation on a Parrot AR Drone 2.0, which is based on kernel 2.6.32; however, I am running into ...
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1answer
533 views

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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5answers
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Why isn't Linux embraced as the official GNU kernel?

While I knew for quite some time the existence of Hurd, and its mission as the official GNU Operating System kernel, I was wondering how come Linux is not embraced as the official GNU kernel over the ...
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43 views

Can a kernel preemption happen in the process context with `TASK_INTERRUPTIBLE` state?

If a process sets itself to the sate of TASK_INTERRUPTIBLE, can it be preempted by other kernel components? If it does, I think this process maybe lost wake-up chance due to failed to check the ...
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3answers
61 views

Legal status of an embedded Linux case

I wanted to find the source code of embedded Linux that is used in Shenzhen Apexis Electronic Co.,Ltd products. For example in this page: http://apexis.com.cn/productsdetails_244.html You see they ...
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1answer
22 views

How To Induce RO To Linux FS

I've read in several places that during I/O error to system log file most linux distributions go to read only mode. Followed by how to recover from it. This is all fine, but I'm looking for a way to ...
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1answer
23 views

How to get kernel messages on serial console on a systemd system?

I'm trying to set up an A20-OLinuXino-LIME2 as a headless fileserver with a Debian 8 image from Igor Pečovnik's builds. I would like the system to output its kernel messages to the serial console ...
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24 views

Unknown symbol in module

I have a kernel module which is was probably written for kernel version 2.6xx. Now currently I want to plug that module onto kernel version 3.1x and above. I have tweaked and change the code and ...
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1answer
41 views

Linux process - messages from kernel [closed]

I have been learning about different IPC mechanisms present in Linux, for communication between user space processes. I want to ask what are various ways in Linux for the kernel to communicate with ...
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1answer
29 views

Booting encrypted disk kernel error: Cannot initialize device-mapper

I have Ubuntu 15.04 with a default full disk encryption installed on my chromebook Pixel with linux-samus kernel patch and everything is working fine. I've just tried compiling a newer version of the ...
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0answers
18 views

APEI Generic Hardware Error : PCIe error with ATTO SAS HBA

Recently we upgraded a remote server to a new Dell PowerEdge T630 with dual CPUs (so all PCIe slots are active). It had been running for several weeks fine before we added an IBM LTO5 tape drive that ...
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0answers
10 views

SystemTap log output to file

I want to log output from my SystemTap script to a file. But when I try to use the -o option like: stap -r $PWD --remote user@hostname -o test.txt -S 1 ./test.stp I can't find the log file. If I ...
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1answer
578 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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1answer
70 views

Changing the TCP RTO value in Linux

I will like to alter the TCP RTO (retransmission timeout) value for a connection, and some reading I have done suggests that I could do this, but I don’t where and how. I have looked at the ...
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1answer
99 views

Understand Linux kernel virtual bridge port numbering

I have a Linux kernel virtual bridge which contains interfaces eth1 and tap0: # brctl show br0 bridge name bridge id STP enabled interfaces br0 8000.00016c404fa3 ...
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0answers
311 views

Can I make the boot even more verbose than loglevel=7 using kernel parameters?

I have an error when booting on a machine, my machine is stuck with the error message: Booting a command list. I can see this message when I add loglevel=7 and only if I delete the quiet in the ...
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2answers
663 views

No build scripts available when compiling module outside of Linux source tree

I am attempting to build a basic module outside of the Linux source tree (3.18.0-rc6). When I build it, I get an error saying it couldn't find scripts/... My directory setup looks like this ...
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163 views

Can't get Kernel image

I am trying to write the kernel image in my ARM, I am using an ARMStone a9 here is the information about this board: http://www.fs-net.de/en/products/armstone/armstonea9/ The problem is that I am ...
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1answer
2k views

How to fix make error “No rule to make target 'menuconfig'” when building a kernel for Beagleboard?

The aim is to build and install the USB Video Class (UVC) module, via make modules_install. I'm trying to configure the kernel via make menuconfig on Angstrom distribution, running on BeagleBoard-xM. ...
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1answer
27 views

What is the register %gs used for?

All I was able to find out about the %gs register is, that it seems to be a free to use register on >32bit x86 architectures. It seems that a gs_change is executed before any system-call. Can someone ...
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1answer
36 views

What is the impact on system performance when kernel debug info is enabled?

In order to debug kernel or use tools like stap (https://en.wikipedia.org/wiki/SystemTap) kernel must be compiled with full debugging information included - namely option CONFIG_DEBUG_INFO has to be ...
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1answer
15 views

Case study of virtual memory management

Need help in understanding virtual memory concept. When a process requesting for 2GB mapping onto the virutal memory in Linux environment of 4GB ( 1GB Kernel : 3GB Userspace), when already another ...
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2answers
47 views

Telling Linux kernel *not* to use certain CPUs

I'm trying to run some benchmarks on a multicore machine and I'd like to tell the Linux kernel to simply avoid certain cores unless explicitly told to use them. The idea is that I could set aside a ...
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1answer
20 views

bluetooth - btusb module remove stops bluetooth service

I just faced a strange issue; Every time after suspend the btusb module is kicked out the RAM (for some reason but its OK cause I can reinit it manually) but as a result the bluetooth.service must be ...
2
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1answer
30 views

How does the kernel decides what pages commit to swap?

If RAM usage is higher than the level written in «swapiness», kernel will use SWAP. Ok. But how does the kernel «order» programs? Is it «first come, first served» for RAM? Or biggest programs in ...
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1answer
43 views

Kernel memory leak detection [closed]

How are memory leaks identified in Kernel. Not sure if Valgrind can be used in this case.
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Linux Angstrom can't start without serial cable plugged

I'm using the Altera Cyclone V Soc dev Kit and Linux Angstrom provides by rocketboards (http://rocketboards.org/foswiki/Documentation/GSRD141) Kernel is : 3.10 LTSI Linux can't start if any serial ...
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1answer
594 views

Enable kernel's net_key, inet_esp, crypto_hmac modules for to use in a VPN

I'm trying to turn on modules for VPN so I followed this tutorial to compile new ubuntu kernel 3.8.6 . But the features I've turned on using make menuconfig seem not to be enabled. (the features I ...
3
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1answer
42 views

How do I detect that my system has auto-rebooted after a kernel panic?

I'm using Linux in embedded systems, and want to configure the system to automatically reboot after a kernel panic. However, when the system comes back up, it's important for me to detect and log the ...
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1answer
46 views

routing table “220” in Linux kernel 3.2.0-23-generic

I have a Linux machine with kernel 3.2.0-23-generic and it has rule with priority 220 in RPDB which points to routing table named "220": T42:~# ip rule show 0: from all lookup local 220: ...
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5answers
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Why is the Linux kernel called an “image”?

I often hear people refer to the Linux kernel as the Linux kernel image and I can't seem to find an answers on any search engines as to why its called an image. When I think of an image I can only ...
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2answers
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Error while installing wireless-bcm43142-dkms-6.20.55.19: dependency linux-headers is not satisfiable

I have to install a .deb file with the firmware for the wifi card (This is the name of the file: wireless-bcm43142-dkms-6.20.55.19_amd64.deb; I've downloaded the file from here: ...
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1answer
575 views

Determine whether kernel built-in driver supports a device

I'm trying to find a way to accurately determine whether all the hardware on some system has a valid driver installed either via a kernel module or built-in to the kernel. I'm working with RHEL 5.5 ...
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1answer
47 views

routing cache in latest Linux kernels

As I understand, routing cache was removed since Linux kernel 3.6. In systems with older Linux kernel one could view the content of the routing cache with ip route show cache command and routing ...
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3answers
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What does the Windows flag in the Linux logo of kernel 3.11 mean?

I've just installed kernel-3.11.0-1.fc20 for my Fedora 19 installation. During the rebooting progress, I saw the Linux logo with a Windows flag in it, what does it mean? The Fedora 19 is installed ...
11
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4answers
738 views

Using real time kernel headers to compile userspace code vs default headers

Per customer requirements, I installed CentOS 5.6 with the default kernel. With this kernel installed, the time.h file includes the #define CLOCK_MONOTONIC. Now, a real-time kernel was installed ...
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2answers
3k views

Where kernel configuration file is stored?

I currently run Angstrom Linux 2.6.32. I intend to upgrade linux kernel from 2.6.32 to 3.0.7. For this reason, I had to configure kernel 3.0.7 running make menuconfig. Now, I want to compare the new ...
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1answer
21 views

Trace kernel object calls

We have strace to trace programs, ltrace for dynamic libraries, and others. Is there any equivalent for kernel objects, as in tracing just like strace but for a specific .ko? Thanks
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High %sy cpu usage , server is very slow

On one of the server we are noticing high %sy usage due to which server is very slow. Below is strace count for syscall. What will be the reason for high %sy usage. % time seconds usecs/call ...
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2answers
91 views

Looking for a Distro for a beginner in kernel hacking [closed]

I'm currently trying to learn the basics of the linux kernel via Linux Kernel in a Nutshell and Linux Kernel Development books, the problem is that when using Ubuntu, there are a lot redundant ...
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Arch very long boot-time after kernel downgrade

I just downgraded my arch kernel from 4.x to 3.17.x for the sake of being able to use shared folders feature in vmware. Right now, everything is fine and it boots up too. But boot-time has greatly ...
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2answers
885 views

SIOCSIFADDR: File exists after upgrading kernel

Since upgrading my (Gentoo) kernel from 2.6.38 to 3.3.8 (via oldconfig), I can't get the network on eth0 up anymore. It reports "SIOCSIFADDR: File exists" with a number of other SIOCSIF* errors that ...
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1answer
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what does it mean 'fork()' will copy address space of original process

I'm studying 'operation system concepts' on my own and I'm studying the chp3. process part. There is an example where the 'fork()' function is called and depending of the returned pid value like the ...
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19 views

Minimum required packages for a LFS/DIY-Linux system?

I am trying to make a super-minimal linux system, as a base for experimentation, and just for the experience. I have built DIY Linux (similar to Linux from Scratch) before, but I was wondering how ...
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how to find which linux kernel commit made its way to exactly which kernel version [duplicate]

We have a problem that started appearing in kernel-uek-3.8.13-68.1.2.el6uek.x86_64. Symptoms and description matches exactly this linux kernel developers description ...