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

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How is kstkesp determined for each process? [migrated]

I'm working on a tool that sometimes hijacks application execution, including working in a different stack. I'm trying to get the kernel to always see the application stack when performing certain ...
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how to get 32 bit kernel headers in 64 bit debian jessie installation [duplicate]

aptitude search linux-headers provides this: p linux-headers-3.16.0-4-all - All header files for Linux 3.16 (meta-pack p linux-headers-3.16.0-4-all-amd6 - All header files for Linux 3.16 ...
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Why is the Linux kernel called an “image”?

I often hear people refer to the Linux kernel as the Linux kernel image and I can't seem to find an answers on any search engines as to why its called an image. When I think of an image I can only ...
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linux kernel module building prerequisites

The "How to Build External Modules" section of the kernel.org kbuild documentation ( https://www.kernel.org/doc/Documentation/kbuild/modules.txt ) says: To build external modules, you must have a ...
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Difference in execution of init with embedded vs. external initramfs?

I'm building a very minimal linux system that just consists of the kernel (v4.1-rc5) and an initramfs populated with busybox (v1.23.2). It works fine for the most part, but I observe a difference in ...
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Linux kernel: meaning of source-tree, in-tree and out-of-tree

What do the terms "in-tree" and "out-of-tree" exactly mean? Also, does "source tree" specifically refer to the official kernel released from / maintained at kernel.org or is it a more general term ...
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What does the Windows flag in the Linux logo of kernel 3.11 mean?

I've just installed kernel-3.11.0-1.fc20 for my Fedora 19 installation. During the rebooting progress, I saw the Linux logo with a Windows flag in it, what does it mean? The Fedora 19 is installed ...
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How can I prevent a module from flooding my kernel log with useless output?

I'm using the atmel_mxt_ts module, and it floods my kernel log with useless status messages, about 10 per second. I'm worried this will make my journal massive and cause unnecessary writes to my SSD. ...
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How to explain strange kernel messages?

I have a server running on Debian Wheezy 3.2.68-1+deb7u1 x86_64. Lately strange records in /var/log/messages appeared. First messages of this log starts just after server reboot. 6.222.18 LEN=44 ...
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516 views

Why system call hooking produces different result everytime in Linux/Android 2.6.29?

I have implemented system call hooking for Android 2.6.29 kernel through a LKM module. I am tracing down one Android app for system calls. But interestingly, it returns different results every time I ...
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Is the Linux kernel affected by paging?

Is the whole kernel always loaded to RAM whatever the size of the RAM? In other words, can the Linux kernel be affected by paging (some part of kernel reside in virtual memory)?
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SIOCSIFADDR: File exists after upgrading kernel

Since upgrading my (Gentoo) kernel from 2.6.38 to 3.3.8 (via oldconfig), I can't get the network on eth0 up anymore. It reports "SIOCSIFADDR: File exists" with a number of other SIOCSIF* errors that ...
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593 views

psmouse sync issues!

I have Compaq CQ61-420US (64-bit AMD) laptop with Synaptics touchpad checked using $ egrep -i 'synap' /proc/bus/input/devices N: Name="SynPS/2 Synaptics TouchPad" But recently after Arch Linux ...
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How to debug freeze at start, output of syslog

Every now and then, my computer freezes while starting. I can see some "Oops" in /var/log/syslog, but from there I am not sure what to do to try and fix the problem. Jun 5 12:47:40 fulla kernel: [ ...
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How does the Linux kernel initialize console graphics?

Observation: I switch on a Linux box Boot loader displays its output on screen Boot starts with first output messages Screen goes blank, and never comes back on. Note: this is about the console, ...
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how to make LVMs at available boot? kernel panic - dracut cannot find logical volumes after kernel upgrade in CentOS 6.6

I have a centoOS 6.6 vmware vm that I ran yum update on which upgraded the kernel after reboot, I started getting this: dracut Warning: No root device "block:/dev/vg_myhost/lv_root" found dracut ...
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Qemu Linux(kernel with debugging symbols) and ARM

I'm looking for a Linux ARM kernel, disk image and initrd that is compiled with debugging symbols. I'm looking to debug the kernel using the qemu and gdb. Could you point me to an arm linux image that ...
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Kernel booting stops right after “Uncompressing Linux…”

I'm trying to bring up an ARM-based board. I've got U-Boot working but can't seem to get the kernel to load. Most of the time it only goes as far as: Starting kernel ... Uncompressing Linux... A ...
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1answer
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Linux kernel patches: can I skip some?

I have the source of Linux 3.4.0 to which I added some modifications. I know that here (ftp://ftp.kernel.org/pub/linux/kernel/v3.x/) I can find all the 107 patches that need to be applied to my source ...
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2answers
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Asus X101H - Touchpad not recognized (want to disable while typing)

I have been struggling with this issue for a while and have done an exhaustive search for answers here and elsewhere before posting this question. On my Asus X101H, the touchpad is not recognized as ...
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System accounting misbehaviour on MacOS X (Yosemite)?

On all my Unixes (CentOS, FreeBSD, MacOS X) I activate the system accounting as a basic security rule. On MacOS X (Yosemite, 10.10.3) I see a misbehaviour I am investigating to fix. Everytime I run ...
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Ping IP works, nslookup fails. New Kernel

I am compiling my own 3.14 kernel. I fear I may have left out some important networking feature to get DNS working. I can't resolve domain names. I can ping my DNS server. I can resolve using that ...
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disable transparent hugepages

We are installing SAP HANA in a RAID machine. As part of the installation step, it is mentioned that, To disable the usage of transparent hugepages set the kernel settings at runtime with echo ...
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How to add more /dev/loop* devices on Fedora 19

How to add more /dev/loop* devices on Fedora 19? I do: # uname -r 3.11.2-201.fc19.x86_64 # lsmod |grep loop # ls /dev/loop* /dev/loop0 /dev/loop1 /dev/loop2 /dev/loop3 /dev/loop4 /dev/loop5 ...
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High read/write system call time

I am facing a weird problem with one of process taking more processing time in one system comparing to other systems. Most of the time is spending on read and write system call on problem host. I am ...
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Triggering hardware interrupts by connecting parallel port pins 9 and 10 does not work

I want to trigger hardware interrupts as described in the book Linux Device Drivers by connecting pins 9 and 10 with a wire. I tried that but apparently there's no interrupt beeing triggered: cat ...
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Driver install, kernel source not found

I am trying to install a NVidia Cuda driver on a Amazon EC2. GPU instance (Amazon Linux AMI (HVM) 2013.09.2 - ami-e9a18d80) following the instructions laid out in a blog. It worked for the last two ...
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“Argument list too long”: How do I deal with it, without changing my command?

When I run a command like ls */*/*/*/*.jpg, I get the error -bash: /bin/ls: Argument list too long I know why this happens: it is because there is a kernel limit on the amount of space for ...
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Book for understanding latest Linux kernel [closed]

I want to understand the Linux kernel. For this I have the book "UnderStanding the Linux Kernel, 3e". Inside the book I have found that the book has written based on Linux kernel 2.6. But as my ...
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How to disable core dump generation in Centos (cPanel Server)?

I want to disable core dump generation, How can I disable it ? One of the website keeps generating core dumps every second and eats up all the disk space. OS Details: CentOs cPanel Server ...
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What are the programs/commands which the magic SysRq key invoke?

From Magic SysRq key The magic SysRq key is a key combination understood by the Linux kernel, which allows the user to perform various low level commands regardless of the system's state. It ...
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How do you install the FreeBSD10 kernel sources?

I am trying to run an update of freebsd10 and I am being asked for the kernel sources ===>>> Launching child to update lsof-4.89.b,8 to lsof-4.89.d,8 ===>>> All >> ...
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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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Prevent claiming of novelty usb device by usbhid so I can control it with libusb?

I have a USB rocket launcher that I wish to experiment with through libusb. However, libusb cannot claim the interface; presumably because the output of usb-devices lists 'usbhid' as the driver for ...
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Where is routing table stored internally in the Linux kernel?

When I execute route -n, from where exactly (from which structs) is the information displayed retrieved? I tried executing strace route -n but I didn't help me finding the right place it's stored.
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Why there is PPPd instead of all PPP software in kernel?

Are there any reasons why the need of PPP software separation from kernel and process (PPPd)?
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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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how to untar file in linux red hat?

I am compiling linux red hat stable kernel on red hat linux and the error which I am facing is as below
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394 views

Kernel Backport for Debian Jessie?

I installed the 32 bit version of Debian Jessie (8.0) on an Asus X205TA. The Asus X205TA laptop is quirky like a lot of Intel Baytrail Atom laptops/tablets in that it has 32 bit EFI but a 64 bit ...
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Using dkms to patch kernel

I need to apply a kernel patch(https://lkml.org/lkml/2015/3/31/929) to get my touch-pad working properly. I am thinking that I should be using dkms, to do this. Most of the stuff I am reading is about ...
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1answer
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bdl_pos_adj: set IRQ timing workaround for hda-intel

I get following errors in my logs: kernel: snd_hda_intel 0000:00:1b.0: IRQ timing workaround is activated for card #0. Suggest a bigger bdl_pos_adj Google found some old posts here and ...
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Delayed write scenario

I was reading "The Design of the UNIX Operating System" by Maurice J. Bach and had a confusion. Suppose a process requests for a buffer for disk block number 18. The kernel searches for a free buffer ...
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Kernel modules for compiled kernel

I cannot find kernel-headers. For the first time I compiled and installed the latest kernel (4.0.3) on my Debian Wheezy, and now I am trying to install ndiswrapper using module assistant. For that, ...
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Why does user mode linux spawn 4 processes?

If I start User Mode Linux with this command: ./kernel32-3.19.8 ubda=./Debian-Wheezy-x86-root_fs mem=128m On Debian GNU/Linux 8 (jessie) with one CPU core, why do I see 4 processes in top: 1608 ...
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Linux Driver for USB “reverse” mass storage device

I'm developing a USB device that I want to read and write in virtual filesystems that are in my computer. Basically the device needs to be able to read, write and get the virtual filesystem size. Some ...
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how to check a kernel version which was used when building package

I use apt when downloading packages from Ubuntu repositories. How can I check which kernel version was used when building package? When it is important (kernel version of the build server vs. kernel ...
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Not able to reinstall the kernel or to use the latest version

On a ubuntu server, I try to di "sudo modprob" and I have this error : $ sudo depmod [sudo] password for deployer: depmod: ERROR: could not open directory /lib/modules/3.8.0-38-generic: No such file ...
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READ DMA Error after Installing CentOS 7

I have been trying to install CentOS7. After I installed it, I see the following message sporadically. ata2.00: exception Emask 0x10 SAct 0x0 SErr 0x4050000 action 0xe frozen ata2.00: irq_stat ...
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Downgrade Debian kernel

I have a requirement to install Debian kernel 3.2.65-1+deb7u2. I cannot seem to find the kernel. I have taken the following steps: Installed kernel 3.2.68-1+deb7u1. Downgraded the kernel to ...
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why do some network cards need to load external firmware?

I have read this question/answer, but I still do not understand why some network cards work perfectly well without any additional firmware, whereas others need to load firmware to work. As a specific ...