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

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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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3k 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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59 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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148 views

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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628 views

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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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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333 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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245 views

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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66 views

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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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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337 views

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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61 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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23 views

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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111 views

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 ...
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70 views

How to find out what distros are using particular Linux version?

Given a distribution and its version, I can find which version of kernel it uses, e.g. for Ubuntu they are listed here, and for currently supported versions of Fedora they are here. In general, ...
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What does raw_spinlock mean? [closed]

I was studying struct raw_spinlock which is in the /usr/src/linux/include/linux/spinlock_types.h was like this: typedef struct raw_spinlock { arch_spinlock_t raw_lock; #ifdef ...
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Is there something like “make localmodconfig” that detects *all* your hardware?

I understand that Linux's "localmodconfig" target looks through all your loaded kernel modules and produces a .config file that enables those modules. This is nice, but what about hardware whose ...
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ABRT report says “irq 19: nobody cared”, but why?

Every couple weeks, I need to reboot my system. When I do, and enter as root in the terminal, the following message (in some variation) appears: ABRT has detected 3 problem(s). For more info run: ...
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Kernel config for HP Stream 13 (booting from emmc disk)

I'm trying to install gentoo on hp stream 13 device and i am unable to boot up system from the emmc hard drive. Before trying gentoo on this device i have successfully installed debian, which clearly ...
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Recompile the kernel changing only one option

I've already built a custom kernel based on the mainline 4.1.6. Now I want to disable CONFIG_ACPI_I2C_OPREGION The kernel build is not very short, so I'd like to rebuild only the parts affected by a ...
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67 views

How can I update the kernel and initrd images in EFI boot loader?

I have successfully installed the EFI boot loader (using ELILO) but I am unsure how to actually keep the kernel images up to date. Can you help me understand the process please? Thanks. ...
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Why is debug_putstr() not being printed during boot?

I'm asking myself why debug_putstr() in arch/x86/boot/compressed/misc.c is not being printed during x86 boot phase, though it is configured to do so with GRUB_CMDLINE_LINUX_DEFAULT="". On other ...
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119 views

check-config errors on Linux 3.19.0 kernel, configured under Ubuntu 15.04 x86-64

I'm new to configuring Linux kernels, and am receiving the following errors when running config-check: check-config: /tmp/tmp.tnqExc0fHn/CONFIGS/amd64-config.flavour.generic: loading config ...
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scripts/checkpatch.pl: Warning: consider using a completion

I'm currently writing a kernel driver that involves moving large amounts data from userspace to or from a peripheral, via a ring of bounce buffers. The buffer completion callback ups a semaphore, and ...
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Best way to approach HID_MAX_USAGES kernel errors?

This is an issue I have for the second time now: basically, an USB based device reports some wrong numbers for "HID_MAX_USAGES", resulting in the kernel giving an error message and the device not ...
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What is “state-object” in cgroups

I am gathering some idea about lxc, kernel name spaces and cgroups. While reading man lxc-cgroup, i find : lxc-cgroup gets or sets the value of a state-object (e.g., 'cpuset.cpus') in the ...
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Stack pointer of the interrupt stack

Linux kernel has separate stacks for user mode and kernel mode process and also some special stacks. One of this special stacks is interrupt stack with the size 16 kilobytes placed in the ...
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57 views

Linux modules take a lot of space [closed]

I'm using the 4.1.2 mainline kernel. The package with image and all modules has 207 MB of installed size. I built a patched 4.1.6 kernel, taking the config from the current kernel and now the drivers ...
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35 views

Does MySQL processes run in user or kernel modes?

I try to count IOPS and I/O size with SystemTap script and use MySQL to be workload. I found mysqld doesn't call systemcall but mysqld has read/write on VFS. So, do MySQL processes run in user or ...
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Error while trying to compile/install kernel, 4.1.6 on Ubuntu 15.04

I'm trying kernel compilation in Linux for the first time. I'm using the guide here to learn the basics. I'm able to pull the source code from the git repository, and can compile it. However, I run ...
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X stopped working after a kernel update

My system is a laptop with Ubuntu 14.04, with an Intel CPU and Intel + Nvidia GPU combo. After one automatic kernel update, the GUI stopped working. It shows a blue loading screen with a spinner, up ...
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What's the philosophy behind delaying writing data to disk?

In Linux, a finished execution of a command such as cp or dd doesn't mean that the data has been written to the device. One has to, for example, call sync, or invoke the "Safely Remove" or "Eject" ...
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how to set i2c bus to soc audio codec

I'm working on an audio codec driver for cs4245 device. It's controlled by i2c. I have 2 hardwares (devel-board), one of the them has the codec attached to i2c-1 and another to i2c-2. The first one is ...
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How to add a system call in linux kernel 4.x

I'm trying to add a system call using linux kernel 4.1.6 but all the documentation I can find is for older versions. Does anyone know how it's done in the newer kernels or have any good references? ...
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how practical the number of cores in Android

I've often wondered how practical the cores usage in Android smartphone. I'm asking here because Android is based on Linux. I'm looking from technical perspective. The articles that I've read so far ...