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

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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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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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59 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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57 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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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 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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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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146 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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55 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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313 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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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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31 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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81 views

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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364 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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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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108 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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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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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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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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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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453 views

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, ...
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Noob Kernel Image Question

I'm playing about with CM-FX6 , an iMX6 based SOC. The chip comes with the following: http://www.compulab.co.il/workspace/mediawiki/index.php5/CM-FX6:_Linux:_Kernel **images** uImage-cm-fx6 - ready ...
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Why is there no rootfs file system present on my system?

The linux kernel documentation claims: Rootfs is a special instance of ramfs (or tmpfs, if that's enabled), which is always present in 2.6 systems. You can't unmount rootfs … On all linux ...
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Booting into a kernel image

I have a recently-compiled Linux kernel image (vmlinuz file) and I want to boot into it. I am aware that this won't give me a familiar Linux system, but I am hoping to be able to at least run some ...
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1k views

Linux freezing guess: keyboard & mouse (Archlinux and Ubuntu)

Linux on my PC is freezing a few seconds after startup. I am unable to use the mouse / keyboard. Neither Ubuntu nor Arch do anything after a few seconds. Windows has been running fine for years now. ...
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455 views

Linux: Is there a IPv6 equivalent to the IPv4 kernel option accept_local?

Since linux kernel >= 2.6.33 the kernel option "accept_local" can be modified: /proc/sys/net/ipv4/conf/${interfaceID}/ accept_local - BOOLEAN Accept packets with local source addresses. ...
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913 views

Why kernel 3.6.2 is so much less energy efficient than 3.6.1 on Mint 13?

I noticed, that the power consumption in my ASUS P53E notebook is doubled (from 10W to 20W) when I change from kernel 3.6.1 to 3.6.2 (or later). I use Ubuntu Quantal mainline kernel from ...
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How to install/make the kernel section 9 manpages which document its functions and data structures?

The kernel sources contain functions and data structures which are documented, for instance in panic.c: /** * panic - halt the system * @fmt: The text string to print * * Display a message, ...
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249 views

How do I compile the linux kernel version 3.16.1 to run in Slackware 14.1?

Could someone teach me or give me some tutorial? How do I compile the linux kernel version 3.16.1 to run in Slackware 14.1.
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LVM2 Mirror Support Missing from Kernel after System Migration

I had a system that was running on a small netbook that had LVM2 set up to group two external USB hard drives into a volume group, and to use that volume group to create a mirrored logical volume. ...
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What is the difference between the following kernel Makefile terms: vmlinux, vmlinuz, vmlinux.bin, zimage & bzimage?

While browsing through the Kernel Makefiles, i found these terms. So i would like to know what is the difference between vmlinux, vmlinuz, vmlinux.bin, zimage & bzimage?
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After upgrading the kernel, the sound no longer works

I have updated the Linux kernel on my system to Linux 3.11-2-amd64 #1 SMP Debian 3.11.10-1 (2013-12-04) x86_64 GNU/Linux. Having done that, the sound no longer works. Distribution Info(cat ...
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Detecting kernel thread on pre-3.0 kernels

Looking at the proc man page (http://man7.org/linux/man-pages/man5/proc.5.html) it is possible to detect which processes are kernel threads in /proc/<pid>/stat by looking at the flags value ...
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Generate what a GRUB2 kernel line would look like

In GRUB 0.97 we were able to see what the kernel line/options would look like by just viewing /boot/grub/grub.conf. Now the only way I know how to check the next boot kernel options/kernel version ...
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55 views

sysrq-trigger doesn't accept parameter 'g'

I'm trying to debug the kernel. But I couldn't trigger kgdb with echo g > /proc/sysrq-trigger, it just prints help message. I have enabled kernel debugging, kgdb over serial, frame pointer etc. ...
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Kexec immediately after Kickstart install (where is cmdline?)

I used to be able to kexec into a new kernel immediately after a kickstart (anaconda) install via pxe. I was able to do this by figuring out the current kernel version, and grabbing cmdline options ...
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Warning for kernel “make config” command without sudo

while trying to configure kernel before compile, when I give this command without sudo privileges: make config I get these: /boot/config-3.2.0-4-amd64:488:warning: symbol value 'm' invalid for ...
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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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Installing a new OpenBSD kernel “safely”: why does `make install` go through these extra hoops?

After building a new OpenBSD kernel, the install target of the kernel Makefile does the following: rm -f /obsd ln /bsd /obsd cp bsd /nbsd mv /nbsd /bsd I understand that the first two lines remove ...
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“disagrees about version” message

I get a message "disagrees about version" on boot time, after compiling kernel and modules with KGDB. Why should this happen ? Is there any problem with KGDB ? This is the relevant log at boot: ...
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Resume from Suspend/Hibernate issues

I have a peculiar problem while trying to resume from both suspend and hibernate. I believe the problem to be within the kernel itself since I have tried different distros (Ubuntu, Suse, Mageia) on ...
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/lib/modules/2.6.37.6/build missing in linux puppy? what should I do?

I am new to linux as of yesterday. I'm using linux puppy to try to get the most out of a 10 year old, slow laptop. I installed it fine, no problems there, but as soon as I try to use my usb dongle's ...
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479 views

What happened to `vga=ask` in newer kernels?

I used to activate framebuffer mode in the "older" kernels with vga=ask, and later setting it to a value, once I've figured out which one works best for me. Now, this option seems to be gone, the ...
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How to boot on a ramdisk?

I'm working on a linux embedded for a custom board with a ARM9 processor. My kernel version is : 2.6.33 I'm trying to boot on a ramdisk, kernel correctly mount the file system but failed to execute ...
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856 views

Apt-Get Install Unmet Dependencies

My debian computer will not install the new kernel. It says I have unmet dependencies, and those dependencies say they have unmet dependencies. Many of these dependencies are already installed ...
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What does __ prefix before some kernel api's convey?

Why do some function calls in kernel specially have this prefix __ example: __init initialization(void) is __init a macro? What does this convey? Are these a special class of function calls inside ...