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

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RHEL 5 Kernel Panic

I performed some fdisk operation on vmdisk. After rebooting I got the following error: unmounting old /dev unmounting old /proc unmounting old /sys switchroot: mount failed: No such file or directory ...
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Syn list length increase(backlog queue)?

How does backlog length increase follow way does not affect centos echo "net.ipv4.tcp_max_syn_backlog=1024" >> /etc/sysctl.conf I use centos 6.7
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module issues with kernel

I am currently getting this error message:- iptables v1.4.12: can't initialize iptables table `filter': Table does not exist (do you need to insmod?) Perhaps iptables or your kernel needs to be ...
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Qemu - debug new syscall

as a school project I have to add a syscall to the latest stable linux kernel. I did and recompiled the kernel using make defconfig and make. After going through several tutorials to boot the kernel ...
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What's the Debian way to retain a kernel config change through updates?

I have an embedded system running Debian. It is supposed to auto-update in order to pull in security fixes. But Debian's default kernel lacks a hardware driver that this system needs, so it will need ...
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259 views

Install USB2Lan Driver on Debian 8 (Jessy)

I've installed Debian 8 netinst. get make, gcc, linux-source-3.16 ... Here is the lsusb list: root@Filter:~/smsc7500# lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 005 ...
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system user + kernel time using /proc/stat

user: normal processes executing in user mode nice: niced processes executing in user mode system: processes executing in kernel mode idle: twiddling thumbs iowait: waiting for I/O to complete irq: ...
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108 views

Git “write failed, file system is full fatal: unable to write new_index file”

I am running OpenBSD 5.7 and am modifying the kernel for a university assignment. It's running in a virtual machine. I cloned the repository into '/usr/src' and started to modify 1 file. I went $ ...
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Problem while installing ReviewBoard on Oracle Linux 6.2

I am trying to installing ReviewBoard on Oracle Linux 6.2. For that first of all I have installed a epel-release-latest-6.noarch.rpm provided by Fedora. Then when I am trying to give command yum ...
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Building a kernel

I'm trying to build a custom kernel and I try to build it using make command but I get a No targets specified and no makefile found. Stop. error. Then I searched for the makefile in the folders ...
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220 views

How does FreeBSD allocate memory?

I am aware that this is simplified/generalized explanation, but top(1) utility divides memory in FreeBSD into six pools- Active, Inactive, Wired, Cache, Buffers and Free. Example from top(1) output: ...
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what is left inside the cache even after clearing the page cache data?

I was trying to clear the cache using echo 3 > /proc/sys/vm/drop_caches Even after performing the above operation there remain some space inside the cache? When I check with free -m around it ...
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initramfs kernel panic!

I have seen this problem report a few times but the solution everyone posts is not seeming to work for me and I get the same issues Usage: switch_root [-c /dev/console] NEW_ROOT NEW_INIT [ARGS] ...
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186 views

CentOS installation of new kernel

I have a remote Server with OVH where they have their customized kernel which is causing us a problem while installing our software using CentOS 5.10 While applying the procedure to install the ...
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67 views

Kernel modules still loaded after crash, can't unload them

I've found a funny behaviour in the Linux kernel (version 3.19.0). We were testing a network driver and the system hung completely, it didn't even responded to SysRq commands. After the reboot, the ...
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how do I safely delete old kernel versions in CentOS 7?

I might be encountering odd symptoms resulting from competing kernels in CentOS 7. So how do I safely delete the old kernels? And how do I know which kernel is the newest one? Below is the ...
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Where exactly is page permissions set in fs/binfmt_elf.c?

As I understand that in linux, the ELF loader (binfmt_elf.c) is the one that loads a particular binary into memory. Usually data will be RW and code segment will be RE. But where exactly in the source ...
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Problems compiling Kernel 4.2 Under Debian Linux (Jessie)

This is my first attempt at compiling a Kernel. I have a fresh minamalist Debian Jessie installation, I then... sudo apt-get install git fakeroot build-essential ncurses-dev xz-utils sudo apt-get ...
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Error when booting new kernel - overlays [closed]

I'm trying to boot my first custom kernel from Linus's latest repo: During the decompressing stage I get the following error: Could not find overlay #6 ### dt-test ### of ...
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How can I get the information about the owner of the page [closed]

If have the pointer to structure page i.e. struct page *page how can I use this pointer to get the information about the page i.e. who is the owner of the page, the page belong to which process etc.
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253 views

What type of file is /dev/core or /proc/kcore?

While scanning a filesystem for changes with a shellscript, I forgot to exclude /dev, so core got tested too. Strangely enough, which ever way I test it, it is not consistent for a type: $ if [ -f ...
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96 views

Page cache elimination in Linux kernel

Optimizing the page cache space for less memory utilization in some system where systems don't have swap space and external flash drive or hard disk. Is there any possibility that if we can remove or ...
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5k views

Your kernel headers for kernel 3.10.0-229.el7.x86_64 cannot be found

When I type the command service vboxdrv setup in my CentOS 7 terminal, I get the following error: Your kernel headers for kernel 3.10.0-229.el7.x86_64 cannot be found How can I resolve this ...
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Compiling kernel module Debian 7.9 xillybus

I'm having problems to compile XIllybus kernel module. As this official guide explains (on the top of page 8 of 25) I unpackaged the tar.gz file and compiled the kernel module by typing the make ...
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Filtering bridged packets by IP address

I am using a small Ubuntu 12.04 box as a Wi-Fi Access Point. The box has two interfaces which are bridged together as follows: brctl addbr br0 brctl stp br0 off brctl addif br0 wlan0 brctl addif br0 ...
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67 views

replace new linux kernel with make

Nowdays, I have to compile linux kernel more and more... So : make /home/mohsen/K=kernel menuconfig make /home/mohsen/K=kernel make /home/mohsen/K=kernel modules_install install Question is , ...
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How does a chroot system interact with the kernel

I am trying to debug an OpenGL issue in a piece of closed source software. The software supposedly works in Debian Wheezy and I would like to get it working in Arch. I tried running it in a Debian ...
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Kernel Panic - not syncing : Attempted to kill init

Cloning a hardware image using clonezilla at VM Workstation and getting the following error. I am able to boot the system using rescue CD , but don't know how to proceed.
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What decides which kernel modules are built in the kernel statically during compilation?

I just compiled a new kernel and asked myself: What decides during the compilation process which kernel modules are built in the kernel statically? I then deleted /lib/modules, rebooted and found ...
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85 views

What is the effect of smaller pages?

Does a smaller page size lead to smaller page table(s)? If so, is that good or bad !? I think that this lead to more data handling. Is it possible: to test that within Linux manually or that ...
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Run Linux kernel on Raspberry Pi together with Crosswalk

Is it possible to run the Linux kernel on a system like the RPi and have the Crosswalk runtime on it too. I would like to create an app that runs using Crosswalk on the RPi or any other sytem, but the ...
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646 views

How can I know if my kernel has ExFAT support?

I would like to know if some ExFAT formatted SD card (or pendrive, USB hard disk... etc) will be read by the kernel of my installed Linux distro. I know that, since about 2013, most kernels include ...
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Why kernel modesetting, instead of privilege separation?

Kernel modesetting was kind of painful to get on Linux at first, but now it's pretty awesome to have. I mean, X not need to run as root? High-res hardware accelerated consoles? Cool stuff. Problem ...
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Linux version string config - what should I call my custom kernel release?

Suppose I'm about to ship a smart toaster running SysToast, which is my custom Linux-based high-level system. The kernel is (heavily) based on source version 4.1.6-1-ARCH (I interpret this as: ...
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decrease kernel boot log verbosity level

When my kernel boots, apart from the useful important information, it prints lots of debugging info, such as .... kernel: [0.00000] BIOS-e820: [mem 0x0000000000000000-0x000000000009d3ff] usable ...
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weak-modules from module-init tools directory

I see in module-init directory, files named as weak-modules*. bash # ls /usr/lib/module-init-tools/weak-modules* /usr/lib/module-init-tools/weak-modules /usr/lib/module-init-tools/weak-modules2 ...
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What hardware components do not require driver and why

This is a question that I had in my mind long ago but just now resurfaced back after reading this article. May I know why CPU and memory do not require driver? What other hardware components do not ...
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112 views

Do i need to recompile the whole linux kernel

If I change some part or some subsystem of Linux kernel, do I have to recompile the whole kernel? Is there any way to recompile only that particular subsystem?
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xenix (sysv) file system doesn't support since kernel 2.1.21

xenix filesystem equvalent sysv filesystem, man mount says: Note that,cohorent, sysv and xenix are equvalent and that xenix amd cohorent will be removed at some point in future use sysv instead. ...
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Cpu and memory utilization is high in Aix

Hello everyone, I have problem with my CPU utilization I am using sar command to know my cpu idle % in that idle percentage is null and %sys %usr utilizing more, I am trying to check with ...
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72 views

Can grub load a kernel from HTTP?

Typically the kernel file is loaded via disk. Questions Is it possible to load it via HTTP/HTTPS? If so how?
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Production ready derivative from LFS

I've recently started delving into LFS and have been wondering if there are any popular or well-used distros that have been derived from LFS or BLFS. There are a few of completed projects on Github ...
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What is the command in linux, or a utility to know the current comand status (process status)

For example when I write telnet abc.wtf the telnet session begins saying trying to connect so and so IP, but is there a command that I can type in and know what is the current process happening to ...
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Looking for a distro that has linux kernel 4.0? [closed]

The computer I'm looking to upgrade to linux has a wifi card that isn't supported in linux but I read somewhere that it is supported in the 4.0 kernel. Because of this I can't install an old kernel ...
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lock_kernel declaration

I was trying to get usbip to work on my Mint netbook with Linux 3.2. The repo package doesn't have the require kernel module and the source won't compile. So I set off to fix it. I don't know the ...
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How do I check the running kernel version?

While troubleshooting a problem with my ethernet card, I've found that the driver I'm currently using may have some issues with old kernel versions. What command can I use to check the kernel version ...
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Compiling FreeBSD on OSX

I currently have the source for the FreeBSD kernel. I want to compile it and create an iso image, on my OSX 10.9 computer. Can this be done? Do I need any other tools?
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4.2 kernel build, missing version.h

I have installed a 4.2 vanilla kernel on Kali Linux 2.0 and prepared the kernel source with make clean prepare I then copied the source to the /usr/src/linux-4.2 directory. And this is symlinked to ...
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Is information security less hard in an open source system? [closed]

In the excellent article Why Information Security is Hard - An Economic Perspective, Ross Anderson poses that: ... you can make the security critical part of the system small enough that the bugs ...
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On page fault, how does Unix determine if the faulting address is in swap space?

When a page fault occurs for a virtual address for any process how does the linux/unix operating system determine whether that page (of that virtual address) was swapped previously present in memory ...