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

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Compiling the kernel with default configurations

Assumptions: The platform: anisha@linux-dopx:~/> uname -a Linux linux-dopx 2.6.34-12-desktop #1 SMP PREEMPT 2010-06-29 02:39:08 +0200 x86_64 x86_64 x86_64 GNU/Linux The kernel downloaded is the ...
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Kernel Panic - Can't find root filesystem / error mounting /dev/root

From here: http://fedoraproject.org/wiki/Common_kernel_problems#Can.27t_find_root_filesystem_.2F_error_mounting_.2Fdev.2Froot A lot of these bugs end up being a broken initrd due to bugs in ...
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critical section for linux

In linux or a library for linux, is there an equivalent to critical section in win32? I am aware of Mutex, but it is not the same as critical section since a critical section uses user-mode spinlock ...
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1answer
371 views

What do the kernel options in braces mean?

I saw a kernel option today in menuconfig that used braces for its checkbox. {*} Button This isn't listed in the legend at the top of the screen. [*] built-in [ ] excluded <M> module &...
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2answers
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Multiple root options in Linux command line

My kernel command line looks like this: root=31:0 ro noinitrd console=ttyS0,115200 root=/dev/mtdblock2 rootfstype=squashfs I think the first root entry identifies a disk by its major and minor ...
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3answers
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How do I tell what version of Gentoo & Linux is running?

Is there a way to tell from Bash what distro version # I'm running and also what Kernel version is included?
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1answer
828 views

Compiling and installing a kernel.org kernel to a custom volume on disk

I want to compile and install a kernel.org kernel on a custom HDD volume, say /dev/sda5, instead of being merged with my current Ubuntu's directories. I can find information about configuration and ...
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1answer
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How does the Linux kernel decide how much bandwidth to allocate to Isochronous USB endpoints?

As far as I'm aware, USB endpoints that use isochronous transfers have a 'wMaxPacketSize' parameter associated with them that is used by the kernel to guarantee a certain amount of bandwidth for the ...
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What does the 'i8042.nomux=1' kernel option do during booting of Ubuntu?

I have a laptop with a multi guesture touchpad. My touchpad never works in any Linux distro such as Ubuntu, Fedora, openSUSE, Linux Mint, Knoppix, Puppy, Slitaz and lots more. I have tried lots of ...
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1answer
916 views

kernel panic error after recompilation

I am completely blocked, but temporarily. I have an Ubuntu 11.10 in good condition, in this one I installed VirtuelBox. I installed on VirtuelBox as Ghest Debian Squeeze with Kernel 2.6.32-5-686. ja '...
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2answers
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How does X map from kernel key scan codes to a keysym?

According to this page there is no direct mapping from udev key mappings to X, it has its own mappings. X has a (quasi) total independent way of mapping keys: X reads the kernel keycode table at ...
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109 views

Is it the process that cleans itself on termination or the kernel?

Recently I found this in a powerpoint presentation: When a program is compiled and linked, the linker inserts some extra code in the program. It is this code that calls the main function about the ...
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4answers
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How can same fd in different processes point to the same file?

Say I have process 1 and process 2. Both have a file descriptor corresponding to the integer 4. In each process however the file descriptor 4 points to a totally different file in the Open File Table ...
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1answer
751 views

System call invokation methods in new kernel

I read that in the newer kernels system calls are invoked using the INT X80 instruction and also using the sysenter instruction. And also the sysenter instruction gives faster invocation as compared ...
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1answer
517 views

Unable to access linux/skbuff.h

I am writing a kernel module where I need to access sk_buff variables. But when I write #include <linux/skbuff.h> Netbeans says it can't locate that header file.
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988 views

Best method for testing android kernel

I would like to test some of the features of android kernel like inserting a module and collecting certain parameters for research purpose. What would you think the best method for that?
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What's a NM thread?

I am studying OCFS2 kernel source code and I found this comment of function dlm_lanuch_thread in file fs/ocfs2/dlm/dlmthread.c: /* Launch the NM thread for the mounted volume */ So what does the "...
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5answers
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Any way to restart a Linux machine via SSH if the root filesystem is not working?

Just as a curiosity; something went wrong with a Linux machine, making the root file system show up as "64Z". A few commands work, like top, df, and kill, but others like reboot come up with "command ...
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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 state,...
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1answer
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Is there any X windows system, which is HTML, CSS, Javascript? Such as Web Browser?

For dacades X windows system is either BASH, C or etc. But is there any X windows system or any wrapper which can interpret HTML, CSS, Javascript to general Windows system? I would like to build this:...
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2answers
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Installing OpenVPN to replace Cisco VPN because Cisco will not work with the kernel I am on or downgrade instead?

I had difficulties installing Cisco5.0 VPN on my Ubuntu 10.04 LTS. I asked for assistance in this question: link to previous question. The answer is that this Cisco program will run on only older ...
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503 views

How is the Linux kernel stack organised for ARM architecture?

Can any one explain how exactly linux kernel stack organisation is handled? When a child process is created using the fork() system call, how is the kernel stack space initialized?
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724 views

Choosing a device name under /dev from the kernel command line

I am booting CentOS via a USB install. The boot method is simply booting the ISO from GRUB2 installed on the USB Key. The USB key always gets the "name" /dev/sda. Can I change that name from the ...
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3answers
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How to install kernel on debian with no internet connection

I'm trying to install a newer kernel version on my Debian (squeeze) machine as I need it to get my wireless card working. I have Debian on one partition of my hard drive, Fedora on the other. I'm ...
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1answer
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What does a kernel source tree contain? Is this related to Linux kernel headers?

In books, I typically read references to the Linux Source Tree at /usr/src/linux with the usual set of subdirectories (arch, block, crypto, ...). I was expecting this tree to contain the binary files ...
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Unable to boot VM: Error 13: Invalid or Unsupported Executable Format

I used VMWare vConverter and everything converted fine, but when I try to boot I get an error: The physical machine boots correctly, so I don't think it is a source machine issue. I am not sure why ...
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469 views

Set Kernel Root to Same Partition as Boot

Running GRUB, I want to set the kernel root parameter to the same partition (or more generically, to a partition on the same device) as the disk with the bootloader. Initially, the install set the ...
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1answer
596 views

What are the main differences between Unix and Linux kernels today?

I know that many of the same programs run flawlessly on top of both kernels. I know that historically, the two kernels came from different origins. I know philosophically too that they stood for ...
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1answer
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Will process ids be recycled? What if you reach the maximal id?

Process IDs are strictly increasing, but if your system runs long enough and there is a lot of processes terminating and starting, you could at some point reach the limit of the underlying integral ...
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How to assign USB driver to device

This question is two-fold: First, how do you manually detach a driver from a USB device and attach a different one? For example, I have a device that when connected automatically uses the usb-...
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1answer
790 views

Kernel can not boot after upgrade on Fedora OS 15

I am using Fedora 15, and want to upgrade to version 16. I followed the official link Upgrading Fedora using yum - FedoraProject to upgrade my OS by the following command: yum update kernel* --...
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Why does initramfs mount the root filesystem read-only

What is the reason for the root filesystem being mounted ro in the initramfs (and in initrd). For example the Gentoo initramfs guide mounts the root filesystem with: mount -o ro /dev/sda1 /mnt/root ...
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Restricting memory area for linux kernel

I am running ltib Linux on P1022RDK (P1022 Core) platform. I have 512 MB = 0x20000000 memory. I want my Linux kernel to use the second half of the board memory (i.e from 256 MB to 512 MB) and want the ...
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Make changes to /sys persistent between boots

I want to make "echo 1 > /sys/kernel/mm/ksm/run" persistent between boots. I know that I can edit /etc/sysctl.conf to make /proc filesystem changes persist, but this doesn't seem to work for /sys. ...
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Problem at boot-time: “Loading user-defined modules [FAIL]”

After I updated my Kernel to version 3.0, i always get this line when my Arch-Linux system is booting up: Loading User-specified Modules [BUSY] [FAIL] I have no idea what could cause this to ...
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How can I know which IRQ is responsible of high CPU usage

I've moved a server from one mainboard to another due a disk controller failure. Since then I've noticed that constantly a 25% of one of the cores goes always to IRQ however I haven't managed myself ...
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Signing/Checksumming the kernel to prevent/detect manipulation

All my partitions are encrypted (/ and /home), but the /boot partition has to remain unencrypted and is open for manipulation. I was thinking about hashing the kernel on bootup and checking the result ...
3
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1answer
3k views

Change the number of generated /dev/tty devices

I'm building an embedded Linux system, based on Gentoo. Using udev, all tty devices are probed with a PROGRAM stanza to determine if they are a modem. Right now the system boots up with 64 /dev/tty*. ...
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1answer
18k views

How to generate Module.symvers?

I recently went through Unpacking kernel-source rpm off-system (OpenSuse)?; and as it took > 10 h on my machine, imagine my surprise that after doing the process described there, I find no Module....
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1answer
836 views

Switching from Debian 6 Squeeze stable to testing version

I had this problem and I asked some friends of mine and their advice was to upgrade from my messed-up Debian Squeeze system to the testing version. So I did it. First I changed the /etc/apt/sources....
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rewrite existing file so that it gets replaced by new version atomically, only once fully written

I vaguely recall reading somewhere that there used to be, in some Unices a way to open an existing file for writing, with a flag that asked the kernel to use the old version (for other processes ...
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1answer
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create a debian installer with custom kernel

First what I need to do is install a debian on a 3300mx computer which is based on a vortex cpu. The problem is the debian installer always crash because the required drivers are in the kernel as ...
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1answer
144 views

Is it possible for grub2 to detect some specific CPU features and choose a proper kernel to boot?

I want to configure grub to check some CPU features on startup and choose a proper kernel to boot (e.g. multiple cores -> kernel with SMP support). Is it possible? If so, then how do I do it?
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Stripped down Kernel for a Laptop

I am a Linux noob, but I am willing to learn. My immediate objective is to compile a small kernel for my laptop without sacrificing usability. I am familiar with the kernel compilation steps (don't ...
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1answer
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Is there a way to increase the 20 multicast group limit per socket?

As the title says, is there a way to increase the limit of 20 multicast groups that you can join on a given socket? Is there some system setting that I am missing or is there some hard limit which ...
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1answer
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libusb_init() returns -99

I have successfully built both libfreenect (driver for Xbox Kinect) and libusb (which is a dependency). However, if I try to open the Kinect using the freenect_init(...) function, it returns -99. I ...
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1answer
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How to update Debian kernel to latest in backports

I have a machine running Debian stable, and I'd like to update the stock kernel to the latest kernel available in the backports repository. There are many kernel-related packages and virtual packages--...
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0answers
191 views

What are the current differences between tuxonice and µswsusp?

I tried to find out what is the current comparation between TOI and µswsusp. Unfortunately I could not find any recent information about the state of hibernation in Linux and how TOI compares to ...
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1answer
2k views

What is the difference between /proc/self/stack and output from pstack?

I have been looking through the documentation for /proc and the "stack" object being a new'ish object in proc, I have also looked through the kernel commit to create it -- however the documentation ...
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1answer
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Debian 6.0 system with 2.6.39 kernel dropping packets, sandy bridge hardware

I recently migrated an existing Debian system to new hardware, a core i3 chip running on an intel sandy bridge motherboard. I’m experiencing a very strange problem; when I ping my router, about 50% of ...