The kernel of operating systems popularly known as Linux, or sometimes GNU/Linux.

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Where is the final compiled Linux kernel image located when make vmlinux is ran?

I know this is a rather stupid question, but when I run make vmlinux, where is the final compiled kernel image located? And no, it's not sourcedir/vmlinux (at least for me, neither GRUB nor booting ...
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What Linux kernel configuration options do I have to set to what to support all the hardware of a 13" MacBook Pro Early 2011?

What Linux kernel configuration options do I have to set to support all the hardware of a 13" MacBook Pro Early 2011? I noticed that with all the distributions I tried, none of the FX keys worked (at ...
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What are heap data structures used for (if anything) in the Linux kernel?

Are heap data structures (ordered binary trees) used anywhere in the Linux kernel? If so, what purpose do they serve in the kernel, and which source files and lines can I see their implementation?
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Patching the kernel to allow booting without initrd

The first answer of 'Why does Linux use an Initial Ram Disk at boot?' states that the initrd/initial ram filesystem is used to provide drivers to mount the real root filesystem. It also says that it ...
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How to remove /etc/udev/rules.d/70-persistent-net.rules CentOS

I have a server that we are testing a stretched network failover with VMware Recover Point. When the server moves over to the alternate site, the MAC address changes causing my network interface (...
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Linux kernel hangs at “Starting kernel …”

I have enabled Secure Boot on an embedded device successfully. The problem is that when I am booting in this mode the process seems to get stuck right after the line: Starting kernel ... once U-boot ...
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19 views

Edit sysctl.conf file

Using Red Hat Enterprise Linux Server release 5.11 (Tikanga) but I need to change the values for shmmax & shmall. vi /etc/sysctl.conf # Controls the maximum shared segment size, in bytes kernel....
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23 views

Why does trashing kernel memory result in an instant restart?

Just for fun, I wrote a kernel module that trashes kernel memory starting from 0x7fffffff81000000(for reference, the system call table is at 0x7fffffff81000100) with WP and KASLR disabled. Inserting ...
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5 views

RTSX_USB module loaded but SD card not recognized

I am currently running kernel version 4.6.2-1-ARCH and my integrated SD card reader on my Asus UX31A is not functionning. I have tried loading the module as such sudo modprobe rtsx_usb and then ...
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what is use of put_page and get_page? [on hold]

Linux kernel 3.10.12 Q1)I have two APIs of whcih I am not able to understand the usage. They are:- a) get_page b)put_page EDITED I want the usage of the above functios in tcp_sendmsg.There while ...
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30 views

Fedora Touchpad Stopped Working After Update

So I am on the latest version of Fedora. I have an Acer Aspire E15. I did a dnf update about a week ago (it was probably two weeks out of date at that point) and shutdown. I didn't turn it on again ...
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49 views

Where does a device file come from?

I'm reading through the Linux Kernel Module programming guide and I am a bit onfused about how device drivers work. I tried following along and making a basic device driver, which shows up in /proc/...
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48 views

When does a new system call get added to Linux?

When exposing kernel functionality, there are several alternatives for kernel developers. They can either create a new system call or expose the functionality through /sys, or /proc entries. Is ...
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13 views

Cannot find install-kernel-pkg

I am running Ubuntu 16.04 and am experimenting with building the kernel from source. I am at the step where I want to install the kernel using: new-kernel-pkg --mkinitrd --install --make-default --...
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1answer
44 views

kernel init without 'root=' parameter

From systemd/fstab-generator.c it follows that systemd treats root= as required kernel parameter, the only configuration source for /sysroot mount. However from kernel/init/main.c and kernel/init/...
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8 views

How is the IMQ device positioned in the packet flow of the Linux kernel

I would like to know the exact position of the following device in the packet flow for ingress traffic shaping: IFB: Intermediate Functional Block I would like to better understand how packets are ...
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20 views

How can I learn the purpose of the various kernel processes?

(Related: What do the brackets around processes mean?) I'd like to really understand what I'm looking at better. I'd rather not need to dig through actual kernel source code just for a quick ...
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34 views

How to list the kernel Device Tree

I am using an embedded Arm with a Debian build. How does one list the compiled devices from the device tree? I want to see if a device is already supported. For those reading this, the "Device Tree" ...
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52 views

How does Linux handle drivers when changing systems?

This has always made me wonder but how does Linux handle device drivers from system to system, so say you plug it in on computer A and then move to computer B with completely different specs. In ...
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33 views

Debian 8 crashes once every few days

I'm running Debian 8 on Linode 32 GB and once every few days the system crashes. This server is being used in productions and I need to find a solution ASAP The only server running on Debian is ...
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1answer
45 views

How is the IFB device positioned in the packet flow of the Linux kernel

I would like to know the exact position of the following device in the packet flow for ingress traffic shaping: IFB: Intermediate Functional Block I would like to better understand how packets are ...
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12 views

Build and install kernel module into a defined /lib/module/*kernel directory

I hope someone can help. I had problems with my distribution's kernel, so I built a kernel (same version) to build my modules. My modules would be compatible. However, if I install the modules, the ...
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26 views

How to enable additional audit logging?

We use Auditd to monitor specific changes on Linux systems. Majority of our rules come from CIS Benchmark guidelines and then few are added specifically to monitor certain command executions. We have ...
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Basic mmap implementation [migrated]

I am pretty much new to linux and am writing a custom driver for which I need to use mmap. I have found the sample code in many places as below static int simple_remap_mmap(struct file *filp, struct ...
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22 views

Can't find CONFIG_PCI on menuconfig

I'm trying to enable the CONFIG_PCI option on a custom kernel I work with, but can't find the option. Searching from the menuconfig screen, I see that CONFIG_PCI should be located under the 'Bus ...
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38 views

Round Robin vs FIFO

recently I had to do some reports about scheduling processes in Linux, and to do so, we were asked to turn off all cpu except 0 to show how processes are running for cpu. But there is one thing which ...
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Does linux stops processing related to GUI when we remove the desktop screen from connection from cabinet(CPU box)?

When there is big non interactive software running and if I required more processing power then, after removing the desktop screen does kernel stops processing related to GUI(graphical user interface) ...
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20 views

Does anyone use Netem anymore? Alternatives?

When simulating an IP network you can use Linux built-in network emulator Netem. Together with bridge-utils of course. Simulating packet drop, duplicate packets, jitter et cetera. Is anyone using ...
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What are the differences between Debian Linux Kernel and Linux-libre?

What are the differences between Debian Linux Kernel and Linux-libre in terms of freedom related issues? I know the Debian Linux Kernel can load non-free modules while in Linux-libre they have been ...
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37 views

How to turn off stack protector in linux kernel easily? [duplicate]

I wrote a simple module for the Linux Kernel and it has a stack buffer overflow vulnerability. I want to exploit the module, but I have to turn off the stack protector in the kernel first. How could I ...
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1answer
37 views

How to debug Linux hang?

We are using beagle bone black based custom board, with kernel version 3.12. We are facing system hang during one of the init script,(Which brings up WiFi) this hang happens after random number of ...
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1answer
106 views

check if the Linux kernel my PC runs has been maliciously modified

$ uname -a Linux mypcname 3.16.0-4-686-pae #1 SMP Debian 3.16.7-ckt25-2 (2016-04-08) i686 GNU/Linux I want to check that this ^^ Linux kernel on my PC has not been maliciously tampered with. I have ...
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What is maximum size of any memory segment goes in real life coding?

I'm reading about the x86, In that they have mentioned segment size can go upto 4GB (in 32-bit) architecture. Does anybody knows or experienced the segment size going beyond limit? Or upto what ...
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Pthread scheduler scope variables?

I read that their is 1:1 mapping of user and kernel thread in linux What is the difference between PTHREAD_SCOPE_PROCESS & PTHREAD_SCOPE_SYSTEM in linux if kernel is considering every thread ...
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WCHAN = 0 for a sleeping task?

I am a little confused about the status of a process I have. It looks like this: $ ps -eal | head -n 1 ; ps -eal | grep perf F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD 4 S ...
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22 views

No keyboard input upon boot

I have just finished Linux-from-scratch (7.9). I followed the instructions exactly, and ran into no problems during the build. However, when I booted for the first time, it seemed to boot okay; it got ...
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Is this possible to use a different rootfs that the one kernel comes with?

Here's the situation: I have a compiled zImage that comes with its own rootfs that contains linuxrc. I can extract it using this script. I would like to modify some startup scripts that are part of ...
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Can Linux decapsulate double GRE encapsulation?

For an application when the packets arrive at the receiving host, those packets are double GRE encapsulated (IP Hdr + GRE Hdr + IP Hdr + GRE Hdr + payload packet). I am wondering if Linux kernel in ...
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1answer
53 views

Does linux do outer ip fragmentation

I am looking to understand if Linux has the capability to do fragmentation of the outgoing packets at inner IP or outer IP level? I looked the source code in /net/ipv4/files in Linux kernel source, ...
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1answer
17 views

How to find a specific patch for a kernel file

I've been debugging an issue in my linux kernel and have found a fix for the issue. Checking cross reference, I can see that the fix was applied to that file between kernel version A and kernel ...
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Linux kernel 3.14: Cannot find LILO

I'm trying to compile linux kernel 3.14 on ubuntu 14.04. Before anyone points out, I know newer stable versions of the kernel are available but I have been asked to install 3.14 itself. So, I wrote a ...
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Is there a way to determine compile-time state of a kernel flag from a running system?

I have a running kernel and I'm trying to determine whether it was compiled with support for BTRFS extended attributes. Is there a way to determine a running kernel's compile flags?
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How do Linux kernel modules get enabled in a Linux distro's kernel package?

Although I know how to recompile my kernel to enable a module I want, I'm curious to know how the default Linux kernel modules are chosen in a Linux distribution's kernel package. Taking a comparison ...
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Mint + Kernel 4.5.4: laptop loses suspend state when unplugged

I'm using Linux Mint 17.3 on a newish Asus laptop with Mate desktop. To get the Nvidia graphics and Elan touchpad both to work, I installed the 4.5.4 Linux kernel. I've pretty much got everything ...
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19 views

Strange PFN read from pagemap

I m trying to find the physical page to which a range of virtual addresses are mapped in a piece of C code that I ve written. I m using the /proc/self/pagemap to read the mapping. I ve used the code ...
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Raspberry pi blocks completely after multiple reboots

I have a c++ program running on login on the raspberry pi, this program checks data for multiple devices attached on to it (Arduino Mega 2560 + Modbus RS485), gets inputted data from them and sends ...
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Libraries and linux Kernel 2.6

Which command i can use to see what my current installed software libraries use from the Kernel 2.6? I want to know this so I can check if it would work fine in case I upgraded my Kernel to 3.1.
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psmouse kernel module recompiling

I have a ultrabook and its touchpad doesn't work. Linux mike 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-1 (2016-03-06) x86_64 GNU/Linux touchpad doesn't work and it is also not listed in output of ...