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

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Do kernel threads seem to interfere with full tickless mode?

I'm trying to disable local timer interrupts for low latency. I have full tickless mode enabled in the kernel config and I have the boot parameter nohz_full set for the cores in question. However ...
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1answer
19 views

How to find the source of a currently running kernel on my machine?

I have a Linux 3.14.0 kernel(CentOS 6.2) running on my machine, but the source isn't in /usr/src/. Is there any way to find out the source from which it was compiled? The source is most definitely ...
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Why will plymouth not update?

I admit I don't update my kernel very often. I used to everytime a stable release of sys-kernel/gentoo-sources came out so I'm very adept at doing it. This last weekend I attempted to update from ...
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kernel 3.5 is stable one for ubuntu 12.04 or not [on hold]

Actually I am using Ubuntu 12.04 in my laptop. In that, the kernel version is 3.2.0-32-generic. 8GB Ram and harddisk 500GB in the Laptop. Sometimes the laptop hanged. Because of kernel some people are ...
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30 views

Kali Linux - “package has no installation candidate” (also thinkpad-acpi)

I was trying to install the thinkpad-acpi package unsuccesfully, since it had not found the directories needed at all. (no such file or directory response after running the cat ...
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Mount JFFS2 FS in openwrt

I'm trying to mount 1[MB] of flash as JFFS2 FS in openwrt environment, using 128[MB] NAND flash (4 bit ECC). I'm using the following sequence - flash_eraseall -j dev/mtd6 mount -t jffs2 -o noatime ...
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2answers
758 views

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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45 views

Debian stable: Only GNOME classic with custom 3.16

I compiled a custom 3.16.2 today, which works flawlessly except that GNOME only starts in classic mode. Maybe this is due to changes in the drm i915 driver, but how would I debug this? System is a ...
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817 views

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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yum install kernel-devel: “Nothing to do” [SOLVED]

I need the kernel-devel package to compile a program(How to check if USB WiFi-Adapter is not working or router is out of range?), but when I try to install it via yum, this is the only output: yum ...
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17 views

How to recover firmware on a embedded device with corrupted u-boot and kernel image? [closed]

My embedded device is not working after updating firmware. Thus I tried to update firmware using u-boot. I could successfully get u-boot console via serial connection, but updating firmware failed due ...
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46 views

auditctl reports “File system watches not supported” on a very old system

When I run auditctl -l I got: # auditctl -l No rules File system watches not supported And I've already have AUDITSYSCALL enable in kernel, # zgrep AUDIT /proc/config.gz CONFIG_AUDIT_ARCH=y ...
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third party linux auditing software

Linux has a audit system built-in in its kernel and a user space process called auditd reading the system calls intercepted by the kernel. Are there alternate solutions to the Linux Audit system ? I ...
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1answer
80 views

How to check and set “rhash_entries” parameter?

I'm reading this article, and it says: rhash_entries is the size of the hash table. If you don't specify it on the kernel command line, it is computed dynamically based on the memory available on ...
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Linux 3.x init ramdisk embedded in bzImage?

Is the initial ramdisk embedded in to the bzImage? How to load an rootfs.cpio as a ramdisk and switch the root?
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Understanding IRQs usage [migrated]

In the last couple of days, I've trying to implement a simple interrupt handler in C. So far so good, I think I've achieved my initial task. My ultimate goal is to inject some faults in the kernel ...
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Linux 0.0.1 Kernel - Starting Kernel Programming

To start kernel programming, instead of reading the books, the online references suggested to download the linux 0.0.1 source and find bugs. I have downloaded it and I am going through the code with ...
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1k views

SCTP support for Linux kernel 3.3.4-5.fc17.x86_64

I'm using Fedora 17 64-bit version, with Linux kernel version 3.3.4-5.fc17.x86_64. I installed lksctp using yum. sudo yum install lksctp-tools.x86_64 When I try to run sctp_status -H 127.0.0.1 ...
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1answer
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Real-time executive approach, can be run in desktop Linux?

With the real-time executive approach, a small real-time kernel coexists with the Linux kernel. This real-time core uses a simple real-time executive that runs the non-real-time Linux kernel as its ...
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44 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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Patching and Compiling my Kernel

So I have an issue with my USB 2.0 ports and I believe I have found a solution for it, which is in the below link. https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1210858/comments/32 I have ...
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Some questions compiling linux kernel with make-kpkg

I'm doing my first steps compiling the linux kernel and adding a new system call. I've managed to do it, but I still have some questions. For this task, I has set up a Virtual Machine guesting debian ...
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1answer
902 views

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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557 views

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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33 views

strace works for some builtin commands

I'm trying to understand some kernel level concepts in Linux. I was checking on the difference between shell builtin commands and the other executable commands. This wonderful answer clearly tells ...
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340 views

Loading speedstep_centrino kernel module

Because of a noisy fan in my laptop, I need to change CPU frequency and for this task I need to load the appropriate kernel module. The CPU in my laptop Acer TravelMate 4002WLMi is: $ cat ...
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274 views

ixgbe: increase rx performance

I have an Intel 82598EB 10GBE NIC. I need to receive traffic without packet loss. Data rate is 4-5 Gbps, packet size is 1500-9600 bytes. I had already configured smb and irq affinity. I also tried ...
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6k views

Cleaning log files under linux

I am using a kvm ubuntu 10.04 virtual machine to test some features of a kernel module. I grep through the /var/log files to observe the kernel messages about that module. To start from a clean ...
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682 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
2k views

How to get back from “testing” to “stable” - Kernel downgrade

currently I am having lot's of fun with apt-get - and the bad thing is, it was my own fault. I had enabled the testing packages in /etc/apt/sources.list to install a certain package. And I told my ...
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25 views

rebuilding kernel without using apt-get

I am setting up my Macbook Air 6.2 with Debian Jessie. since I do not have any wireless, I need to set it up manually, but all documentation I find how to do it are using apt-get apt-get install ...
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USB Keyboard Hotplug Module not Working

The following module could be compiled and loaded without any error: #include <linux/module.h> #include <linux/kernel.h> #include <linux/usb.h> #include <linux/usb/input.h> ...
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176 views

Compare two kernel config files from the menuconfig perspective?

I have a situation in which i have two kernel config files (for the same kernel source ). Both of them have a part of the functionality that i need (on one, USB works correctly, on other, the second ...
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1k 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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Given a kernel ATA exception, how to determine which physical disk is affected?

I woke up this morning to a notification email with some rather disturbing system log entries. Dec 2 04:27:01 yeono kernel: [459438.816058] ata2.00: exception Emask 0x0 SAct 0xf SErr 0x0 action 0x6 ...
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423 views

modpost.h:12:23: fatal error: elfconfig.h: No such file or directory

I am running Ubuntu: #lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 12.04.4 LTS Release: 12.04 Codename: precise Kernel info: 3.8.0-38-generic ...
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97 views

What does the CONFIG_NLS_UTF8 kernel option do?

The kernel configuration contains an NLS_UTF8 option. It can be found under File systems → Native language support. What does it do? Its description maintains that it is needed for using a FAT or ...
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1k views

After installing a new Kernel in Ubuntu 14.04, rebooting takes me to busybox initramfs. How do I mount a filesystem after that?

I have a virtual machine with Ubuntu 14.04 in it. I recently built and installed linux-3.14.5 kernel on it, and tried to boot into it, but it drops me to BusyBox v1.21.1 built-in shell. Here's what I ...
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1answer
670 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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496 views

Enable kernel module for 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 ...
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398 views

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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2answers
734 views

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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3answers
4k views

mount.cifs : mount error(12) : Cannot allocate memory

I encountered this problem a while ago when upgrading my kernel but put off upgrading until now. On my system I can happily mount network shares using CIFS running kernel 3.7.10, however when I've ...
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2k views

How to fix unreliable Realtek Wireless card on Ubuntu 13.04

I have a Realtek RTL8188CE wireless card and it works fine when I have a strong signal, but if I get even slightly away from the wifi I lose connectivity even though there is a strong Rx signal. I ...
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Why does each process folder under /proc contain the same information?

Under /proc/<PID>/net pseudo-file system each process seems to have files with the same content. For example I use cat /proc/<PID>/net/ip_tables_names to list iptables tables under the ...
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What are the responsibilities of each Pseudo-Terminal (PTY) component (software, master side, slave side)?

I am trying to figure out how a tty works1 (the work-flow and responsibilities of each elements). I have read several interesting articles about it, but there are still some blurry areas. This is ...
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323 views

Kernel headers for VMware tools

I tried to compile VMware tools on my server. I compiled the kernel myself, I didn't use RPM. As VMware tools needs the kernel header files, I executed the following command in my kernel folder ...
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Linux crashes when i attach usb dongle

I have a D-Link Usb dongle the description about it is: $ lsusb | grep D-Link Bus 002 Device 003: ID 07d1:3303 D-Link System DWA-131 802.11n Wireless N Nano Adapter(rev.A1) [Realtek RTL8192SU] My ...
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how to limit dma address to specific range in linux kernel?

I want to limit the dma address the device can access to 0x0100_0000~0x03ff_ffff. But I don't know how to set the dma_mask and coherent_dma_mask. It's easy to set the "dma mask" for a range start ...
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How does bash execute an ELF file?

When I'm on my Linux Box I use bash as a shell. Now I wondered how bash handles the execution of an ELF file, that is when I type ./program and program is an ELF file. I grepped the bash-4.3.tar.gz, ...