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

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How to to insmod a module build with linux-headers-generic?

I have been trying to make a kernel module, but have run into problems due to the non-standard kernel I am using. I cannot find the headers using repositories, and have not yet been able to get help ...
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Dropped in (initramfs) after installing Zorin OS 11

I am trying to install Zorin OS on Fujitsu Lifebook AH530. The installation runs smoothly, but when system reboots, it drops into (initramfs) shell, with the message: ALERT~ /dev/disk/by-uuid/.... ...
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+50

How to Allocate More Space to Swap and Increase its Size Greater than Ram?

Situation: increase swap size (/dev/sda3) greater than Ram (8 GB) when HD 128 GB Motivation: 8 GB RAM is too little; 30 GB free space in my SSD; I want to turn 20 GB to SSD swap Characteristics of ...
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36 views

How to Study Effect of zram on Memory Size and Paging?

Situation: to study the effect of zram's virtual memory compression (wiki) on memory's size and its speed; when swap is not on HDD/SSD; use zswap if you want to have swap on HDD/SSD Motivation: I ...
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1answer
22 views

How does BeagleBone Black Linux bootstrap change when System 5 init is replaced by systemd? [on hold]

We have BBB based custom Linux board running Linux 3.12. We are current using SysV init for boot. I understand that boot happens in following sequence: ROM code looks for boot device based on boot ...
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Unknown symbol usb_register_driver and usbderegister when inserting the kernel module without GPL licensing

I am a newbie to linux kernel modules. I have written a simple usb driver. The problem that I am facing is when I try to add module to the kernel I get the error "unknown symbol in module". in "...
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i want to tranfer a particular image from one screen to another using serial port [closed]

Can I get a Step by Step guidlines .even they are asking use uart port i dont know how to do it cane anyone help me it will be very greatfull
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12 views

How are separate stacks for different threads allocated in kernel mode for a process in Linux Kernel?

If a system call is made for a process and sitting in kernel mode, if 2 threads are created then a)how are the stacks for each thread is created in kernel? b)If one of the thread switch back to ...
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Can initramfs programs access all memory - do they run in real or protected mode?

This is in the context of current 64-bit processors and current linux kernels (I'm using 4.6.4.) Is it possible for me to write a program that during boot can examine base memory, 640k and under, ...
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54 views

Running a program after system startup directly from the linux kernel

I am trying to run my application directly from the linux kernel (without using cron or something similar). I've tried using ./init/init.c, but it runs too early: $ dmesg ... [ 0.605657] TEST!!! ...
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27 views

How to upgrade kernel with all dependencies in Debian?

I tried to select a newer version in aptitude for linux-image-amd64, but it did not upgrade other packages like linux-headers-amd64 which would likely result in broken system. I must be doing ...
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How to prevent access to HDD during Live-CD operation?

I want to safely disable the harddrive / harddisc (HDD) of my computer with boot parameters. I can not physically unplug it. BIOS / UEFI does not provide me an option to disable it. Can I use the ...
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1answer
14 views

Applying RT_PREEMPT

I'm trying to install a kernel with the RT_PREEMPT patch on a Lubuntu 16.04 distro and running into some issues I'm not sure how to deal with. I've downloaded the sources for kernel v4.4.12 (linux-4.4....
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22 views

Is there a definite way to relate a driver's source code in Linux kernel to the device itself?

Linux kernel's source code contains the sources of drivers for plenty of devices under /drivers directory. Sometimes by looking at the source code comment, it's possible to get a hint of the device ...
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Are there technical limitations preventing root=UUID=<filesystem-uuid> support? [closed]

There is no code in kernel-source/init/do_mounts.c for mounting a filesystem by its UUID, however there is code for mounting a filesystem by that filesystem's partition's UUID. Are there any ...
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Why are these printfs behaving differently? [migrated]

I'm practicing threaded programing and found this. When I printf("1"), the output will comes after a few seconds, but when I printf("\n"), the output comes step-by-step. Why? #include<stdio.h>//...
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2answers
251 views

What is zImage, rootfs

I am very much new to Embedded Linux. We use poky build system. We just use bitbake linux-imx command to build the kernel. It generates some files zImage, rootfs, uboot and also a sdcard image. We ...
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Which Kali Linux kernel image should be chosen and why? What is the difference?

Among the following, which Linux kernel should be chosen and why? How does each of them differ from vanilla kernel? What is meaning of grsec, bpo, rt and dbg? What kind of functionality do they add ...
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23 views

After modifing the source code of existing file system (such as ext2), how to rebuild and install it?

I am now learning the source code of ext2. I think the best way to understand it is to play with it, but I never built a Linux kernel before, so I was wondering if somebody could give me some detailed ...
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How do I access USB endpoints with recent Linux kernels?

I am modifying some dated code (from year 2011; see here) that accesses a USB endpoint in the path: /sys/class/usb_endpoint/usbdevBUS.DEVICE_epENDPOINT/device where "BUS", "DEVICE", and "...
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Are source IPs included in Linux's Ephemeral Port Uniqueness?

From http://aleccolocco.blogspot.com/2008/11/ephemeral-ports-problem-and-solution.html (2008) Linux shares the assigned list of ephemeral ports across all local IPs for unconnected sockets. ...
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70 views

Make kernel: recipe for target failed

I'm trying to get into linux kernels and I found a nice book which I wanted to read. Starting requirement is a readily built kernel which I'm trying to achieve for a few days now. As of now I'm ...
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104 views

Attempting to compile any kernel yields a certification error

I'm currently attempting to follow this guide in order to install the 4.5.7 kernel with Grsecurity on my Kali Linux desktop. I am following that list of instructions verbatim, except for the fact ...
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32 views

Linux or Unix for Isp providers? [closed]

For an ISP providers without thinking about cost and which one is open source or close source. Consider only performance!!!! which one is better than another?and why?
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3.10 kernel changed how it handles scsi / udev behavior

This is a nfs booted kernel and custom initramfs to execute code on bootup. Here is dmesg after that piece completes and pivots into the running file system. https://paste.fedoraproject.org/387110/...
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How are Linux kernel bugs being tracked?

What an hour of Googling bring out that mainstream Linux kernel bugs are being logged in two distinct systems: Mailing list This is the Linux kernel development discussion and bug reporting ...
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why skb buffer cannot be queued on two lists at the same time?

why an skb cannot be queued at 2 list at the same time? I have observed kernel panic while queuing skb at another list even if it is queued in at original list. Let me give an example where even ...
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what does dequeue_task_fair() do in linux scheduler [migrated]

this is a function in linux scheduler, in the implementation of COMPLETELY FAIR SCHEDULER which is in the path: root/kernel/sched/fair.c (link to the file) Now I want to know what does this function ...
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30 views

Linux kernel GRUB/boot issue?

I'm working with a specific software package that is only compatible with a older linux kernel version. After installing this older version via the following command $ sudo apt-get install linux-...
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How to unbind a device from kernel space?

How to unbind a device from its driver from kernel space? I'm looking for the equivalent of echo 0000:00:dev > /sys/bus.../unbind but from kernel space itself.
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70 views

Trying to get my system running without an initrd

I've been trying to configure a kernel that will not require an initrd to boot. I haven't succeeded. The filesystem I'm attempting to boot from is ext4, and I have all the extended filesystems ...
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How to convert from virtual address to physical address and back? [migrated]

I'm given a task to write an application that will talk to a device. However this is not a driver since device is still being developed and the application is intended to exercises its first revision. ...
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linux server memory leakage, it grows inactive memory, how to find the process in inactive memory and to kill?

I have a problem with my Linux cent OS server, leakage of memory grows inactive memory, so how to find the process consists with huge memory in inactive memory to kill
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Linux kernel boot parameters: boot, union

I'm trying to put Debian Live onto pendrive. I know I can do it by simply executing dd if=path-to-iso of=/dev/sdX command but I want to do it more "manually" (just to learn how the things work ;) ). ...
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3answers
130 views

How was kernel written? [closed]

Running a program in kernel mode forbids using standard C library because the only thing your program linked to is kernel itself. So I'm allowed to use functions defined in kernel. But kernel itself ...
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1answer
21 views

Configuration file for kernel in VM environment

I downloaded a fresh kernel that I'm planning on using in a VM. In the instructions of the tutorial I'm using, I'm told You will also need to build a new instance of the kernel, and ensure that ...
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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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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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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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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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1answer
68 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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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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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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56 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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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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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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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" ...