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

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init 0 process is not starting

Yesterday I have encountered one problem, when I turn on my PC it took a long time to boot. After booting it reached to command line with <initramfs> (It is unknown to me what it is) I thought ...
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2answers
83 views

Find or create kernel configuration of kernel binary

I've downloaded a kernel binary which I am using now. In order to use the watchdog on my system I must recompile the kernel with watchdog support. Is it possible to obtain the current kernel ...
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1answer
447 views

Kernel module blacklist not working

I'm trying to figure out how to blacklist modules, and I'm trying it on the usb storage. Unfortunatelly it seems ot have no effect, and I get the module in even if it's not used (apparently). My ...
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1answer
96 views

Booting failing in different Debian and Debian derivated distros?

I've tried Ubuntu, Linux Mint and Debian, even though all have worked great for me I'm keeping with Ubuntu, I tested 12.04, 12.10 and even 13.04. The 12.04 LTS is the one I work with. There's one ...
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3answers
109k views

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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148 views

Virtual address of Global variables in Kernel code

If my understanding is not wrong, every process has a Kernel Address space associated with it (which is typically 1GB). As far as local variables are concerned, they are assigned on the kernel stack ...
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1answer
14k views

What is difference between User space and Kernel space?

Is Kernel space used when Kernel is executing on the behalf of the user program i.e. System Call? Or is it the address space for all the Kernel threads (for example scheduler)? If it is the first ...
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2answers
1k 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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645 views

Kernel Panic after Fedora 19 Update

After installing updates on Fedora 19 (kernel 10.3.7-200.fc19.x86_64) the DE freezes whenever I log in. Using the virtual consoles doesn't work. One time I even got this kernel panic: ...
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1answer
437 views

Is “zero-copy networking” implemented by default on Linux?

I saw this article: http://lwn.net/2001/0419/kernel.php3 Zero-copy networking will be in 2.4.4. This patch, by David Miller, Alexey Kuznetsov, and others, has been in development and testing ...
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309 views

How to build my own kernel ? Where should I start? [closed]

I have completed my graduation recently. And I have only basic knowledge in C. But I would like to work on the Linux Kernel, and customize it according to my needs. Not only customize I would also ...
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1answer
405 views

How to enable VESA framebuffer as default in NetBSD 6.1

When booting NetBSD, the old Tecra 720CDT that I have, works quite nicely in 1024x768x15 mode with vesa fb. I always have to activate VESA when booting the system: > vesa on > vesa 0x116 > ...
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2answers
171 views

Linux Kernel limit access to root with a button?

Is it possible to limit the access to a root account from within the kernel? I mean that if I press a button then the system detects the button being pressed and then allows access to the root ...
5
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1answer
105 views

Upgrade kernel for linux system without upgrading user apps/libs?

I built a custom Linux "recovery-cd" image that consists of a compressed initrd and boots via bcdedit (like Ubuntu Wubi) instead of a physical CD. It has various recovery tools for partition editing, ...
2
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1answer
5k views

Messages from syslogd, what do they mean and what do I do?

Recently, these messages started popping up straight into my prompt when I'm connected to the OpenSUSE system in question via PuTTY: Message from syslogd@host at Aug 5 11:04:03 ... kernel:[ ...
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3answers
709 views

Intentional kernel panic under Linux?

Is there any way to cause a kernel panic under Linux? I've heard of echo c > /proc/sysrq-trigger but it seems to just freeze, and I'm not sure it's a kernel panic. Is there any C program I can ...
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384 views

Linux distro with PREEMPT_RT patch

I want to know if there is any Linux distribution with PREEMPT_RT kernel patch? If not, is there any good tutorial on how to patch and compile a kernel with RT patch and how can I create kind of a ...
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199 views

Linux server crash (kernel NULL pointer dereference + soft lockup - CPU#1 stuck)

I have a Linux 3.2.0-4-amd64 #1 SMP Debian 3.2.46-1 x86_64 GNU/Linux server that keeps crashing, usually once every 24-72 hours. I'm running lighttpd, mysql, haproxy and a couple of always-running ...
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2answers
694 views

Why CONFIG_NO_HZ is not set by default

In the Linux Kernel CONFIG_NO_HZ is not set. But an initial reading suggests that setting that option would be nice from a performance point of view. But reading some posts like this made me think ...
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1answer
176 views

Efficiency of Linux Kernel [closed]

In a documentary, Linus Torvalds says that even in the future, if anyone wishes to make a new OS from the scratch, they could use the Kernel which he wrote. It was very inspiring. Is it true that ...
2
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1answer
2k views

Running make with vermagic kernel string with parentheses causes /bin/sh syntax error

I am on Ubuntu Server 12.04 x86_64 and I need to build Android CyanogenMod 7.2 kernel module. My phone has custom ROM and a patched kernel: adb shell cat /proc/version yields Linux version ...
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1answer
175 views

proc/sys/vm/flush_mmap_pages missing in 3.9 kernel, how to get it?

There was an option in redHat 5.2 called flush_mmap_pages, I could set this to zero and that would turn of writing dirty pages from a mapped memory file (so I can do it myself when I want to). However ...
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3answers
2k views

How can I create my own distro and include a custom kernel & packages? [closed]

I wanted to know how to add packages to the Linux kernel and then package it to a ISO or CD for friends. Thanks in advance and please don't point me to LFS - Linux From Scratch!
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1answer
368 views

DD-WRT on WZR-HP-AG300H: Want XFS support; what firmware has kernel 3.8.13-1?

I installed latest DD-WRT firmware to my wifi router WZR-HP-AG300H. I got the firmware from here (05-27-2013-r21676). I'm currently trying to install XFS file system support because my USB hard disk ...
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88 views

Contents of stack area of a process

I've been going through some Unix text books and I can't have a clear picture on the contents of the stack area of the process. Can anyone please explain or point out some references?
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247 views

Why there are so many problems with the overheating and fan speed when installing Linux? [closed]

I don't understand it. Almost every 10th or 20th question is about fan or overheating or that the fan is too loud and the speed too big etc. And these questions are not only about laptops but often ...
3
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1answer
247 views

Linux signals logger

I'm looking for a signals logger for the Linux kernel, without patching of kernel. I found many articles with patching, but I am not interested in that. I'm running default Ubuntu 13.04. # uname -a ...
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1answer
326 views

How are drivers for peripheral hardware installed in Linux?

I have acquired a new wireless keyboard, and I've tested it out on both a Windows and a Linux box. It worked on both, but with an initial difference - Windows took a minute or two, to look up the ...
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1answer
72 views

Significance of certain folders in linux kernel tree

While going through Linux Kernel Source tree, found certain folders, explanation of which was not seen in the popular sites. Could someone tell why these folders are there like: block - This is not ...
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1answer
555 views

removing kernel modules not working for some modules [closed]

unfortunately i couldnt install a machine with minimal installation as a virtual machine ,so i am trying to prevent loading of unwanted modules from kernel using blacklist file. Added following to ...
2
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1answer
1k 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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69 views

configure allowed_tcp_congestion_control via config files in linux kernel

I am trying to come up with a custom set of TCP congestion control variants as part of the tcp_allowed_congestion_control. I do have multiple variants on my tcp_available_congestion_control list but ...
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1answer
149 views

what is the linux boot param “memmap” equivalent in freebsd

In linux kernel, there is an option to reserve a portion of system ram i.e memmap=512M$2G (boot param) Here 512M starting from 2G would be reserved and not available to OS What is the equivalent in ...
2
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1answer
193 views

apt-get purge <packages> works fine, aptitude still has <packages> marked as installed and reinstalls them

I've created a Rubygem to help with removing old kernels that have built up over years and are eating disk space. (My laptop had 19 kernels on it alone, and on a small SSD...) I want to use apt-get ...
5
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2answers
102 views

Making a process read a different file for the same filename

I have an application that reads a file. Let's call it processname and the file ~/.configuration. When processname runs it always reads ~/.configuration and can't be configured differently. There are ...
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1answer
264 views

How do I prevent system information from being displayed on a terminal?

I'm working on a curses GUI that is supposed to start up automatically on boot-up in the default linux terminal (I have no X server installed). I have this working great, but I have a problem where ...
6
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2answers
685 views

My process was killed but I cannot understand the kernel notice

I have a custom application running on an embedded x86 setup (built using buildroot and uClibc). The application has been running fine but this morning when I returned to work I discovered my process ...
0
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1answer
143 views

How are username, date and time are registered in kernel

How is the date and time of kernel compilation registered in kernel image? cat /proc/sys/kernel/version #35~precise1-Ubuntu SMP Fri Jan 25 17:15:33 UTC 2013
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2k views

Change the size of my memory pages?

I would like to change my kernel's page size from 4KB to 4MB as I have had a large addition of RAM to my computer and I am never running out of anymore. The idea is that programs requiring large ...
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2answers
4k views

ulimit & rlimit in Linux, are they the same thing?

I see people use the terms ulimit & rlimit interchangeably, can I say they are referring to the same thing?
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110 views

Download the Complete Linux Kernel Collection

I am wanting to download EVERY version of the Linux kernel as source code, Debian files, and RPM files. Where can I find a single site where I can download them all at once? If that is not possible, I ...
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2answers
792 views

Enabling UTS Namespaces in the Linux Kernel

When configuring the Linux kernel, what are the advantages and disadvantages of enabling UTS namespaces? Would the new system be harmed if UTS namespaces were disabled?
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1answer
6k views

Understanding RCU when Configuring the Linux Kernel

I am configuring the Linux kernel version 3.9.4. I am being asked questions about RCU (seen below). Specifically, what are each of these and what are the advantages and disadvantages of enabling or ...
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1answer
1k views

Why does building an Android kernel need a toolchain, but compiling the entire source does not?

As seen here, compiling the Android kernel requires a prebuilt GCC toolchain (or the equivalent from the Android NDK). Cross-compilation makes sense; we are compiling code for a device with a ...
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3answers
1k views

cant compile install and Configure any linux kernel in debian 7

I followed these steps from the link: (http://www.howopensource.com/2011/08/how-to-compile-and-install-linux-kernel-3-0-in-ubuntu-11-04-10-10-and-10-04/) but these commands don't work: sudo make ...
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337 views

init: is it a user thread or a kernel thread?

init is the first task executed after kernel is loaded, right? Then who is its owner. also I can see [swapper/0] [swapper/1] ..... [swapper/7] having pid 0 PID PPID CPU TASK ST %MEM ...
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1answer
471 views

Cannot mount eCryptfs

I tried to install eCryptfs on my server to open an eCryptfs I did on my home computer. I got these errors. $ sudo mount -t ecryptfs /home/(place)/enc/ /home/(place)/enc/ Unable to get the ...
5
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1answer
345 views

What does the “00:00:00” timestamp mean in kern.log?

I'm looking for causes of a particular problem in kern.log. There are many entries with a 00:00:00 timestamp: Jun 11 00:00:00 mymachine kernel: [ 0.000000] Initializing cgroup subsys cpusetJun 11 ...
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1answer
440 views

How can I prevent drivers from binding USB devices on a certain bus?

I have a setup with two Logitech Unifying receivers, each receiver has a keyboard bound to it. One of the receiver is to be used by the physical machine to which the devices are connected, the other ...
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1answer
2k views

What is TX status timeout and do I have to worry about it?

Recently, after performing a routine software upgrade, I notice a huge surge in the number of warnings from the kernel that goes like this: warning kern [10839.717480] phy0 -> rt2800usb_txdone: ...