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

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Missing `/dev/sda` when building a minimal kernel for VMware

I'm trying to build a minimal Linux kernel using buildroot that I want to run on VMware, among other platforms. However, when I boot the kernel it doesn't recognize the hard drive (i.e., no /dev/sda). ...
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1answer
42 views

How to find out which Linux kernel versions are the most prevalent?

I am gearing up to do some scientific experiments that involve modifying the linux kernel to collect data on the internal runtime states of certain modules. We want to do the experiments over a ...
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40 views

How to determine if a custom kernel improves system performance?

In addition to measuring boot time and kernel size before and after re-compilation, what are some other useful metrics for determining if a custom-compiled kernel improves system performance? I know ...
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kernel: hpet1: lost 19 rtc interrupts

I have this error that flooding my syslog every day. As a solution on arch linux forum is hpet=disable in kernel command line, but I think it is a bad idea and I searching for another solution. Is ...
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35 views

Linux:how java applications having 1000 threads are managed by 2 CPU's os?

Linux: 2CPU's, 16gb ram Let's say, for example, tomcat having 1000 threads. How this application threads will be shared between two CPU's, and what is the value of run queue length? In my case when ...
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1answer
27 views

Can module loading be globally disabled on modern Linux kernels?

Once upon a time (before kernel 2.6.25), one could use /proc/sys/kernel/cap-bound to drop CAP_SYS_MODULE system-wide, and be assured that the set of code that was presently loaded into kernel space ...
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19 views

Linux: Relation between run queue length and load average [duplicate]

Is there any relation between run queue length and load average?. references appreciated
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12 views

Files backing loop devices opened without O_EXCL

Loop devices are the primary way (and perhaps the only way) to treat normal files as block devices in Linux. It's strange that backing files aren't protected by O_EXCL flag. Why is that? Why nobody ...
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49 views

MT7601 WiFi drivers on uClinux

I have an ARM based board running uClinux on it. It had a working ra0 interface (MT7601 WiFi module) before I recompiled and installed new kernel on it. Before writing new kernel and filesystem to it, ...
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1answer
50 views

what is the difference between vmlinuz vs zImage?

What I know (please correct if my understanding is wrong): vmlinuz: is a compressed, self-extracting, bootable Linux image. Always ELF? Generated how? zImage (or bzImage): are compressed, self-...
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230 views

NVMe PCIe disk power cycling

I want to test a NVMe SSD that is connected to a PCIe slot of my motherboard. The test procedure is a specific algorithm that writes workloads to the SSD, while the SSD is exposed to radiations (e.g. ...
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1answer
39 views

How to block drivers built-into Kernel, i.e. drivers who are not a module

I configured and compiled Linux kernel with nouveau driver built-into kernel, i.e. with <*> as opposed to <M> when doing make menuconfig inside Linux kernel source directory. Now, I ...
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70 views

Is it safe to mount same ext4 filesystem at different mount points?

I know there is option "--bind" for multiple mount operation to handle such case. But ext4 can be directly mounted at different mount points, without option "--bind". So, I wonder whether it is safe ...
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132 views

Add TCP congestion control variant to Linux Ubuntu

I want to test different variants of TCP in Linux Ubuntu. I have Ubuntu 14.04 LTS with Kernel version 3.14. When I check the available congestion control algorithm using the following command sysctl ...
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0answers
33 views

How to play a beep/sound file from the u-boot for Panda-board?

I want to play a Beep/Sound file during the boot up from the u-boot on the speakers connected to panda-board. As this functionality is there in PC ,How to replicate the same on the embedded platform ...
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0answers
132 views

How to compile custom kernel for Raspberry Pi

I'm trying to run the Ubuntu 14 Raspberry Pi ARM image in QEMU, and for that I need the kernel that matches the version used in the image. If I mount the image and run file vmlinuz I see: vmlinuz: ...
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0answers
135 views

switch_root with systemd: “Too many levels of symbolic links”

I'm trying to boot a proprietary kernel build and OS after an upgrade to libc and numerous other tools. I'm booting using an initramfs in the 3.2.0 kernel with some utilities, like busybox. However, ...
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3answers
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On Linux, when does “uptime” start counting from?

My computer says: $ uptime 10:20:35 up 1:46, 3 users, load average: 0,03, 0,10, 0,13 And if I check last I see: reboot system boot 3.19.0-51-generi Tue Apr 12 08:34 - 10:20 (01:45) ...
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2answers
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Saving time while compiling Kernel

I have to demonstrate a practical where I have to make my own module, add this module to a kernel's source and implement the system call. I'm using 3.16 kernel on Ubuntu but it takes around 2 hours to ...
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2answers
1k views

Linux/compiler-gcc5.h: No such file or directory

I run into problem compiling a kernel scheduler for testing the compiling error linux-2.6.32-rc3/include/linux/compiler-gcc.h:86:30: fatal error: linux/compiler-gcc5.h: No such file or directory ...
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1answer
22 views

Finding digest of kernel mailing list

I am looking for the digest of the LKML. The Dell site doesn't seem to have it, even though several places link to it. Additionally, googling just comes up with old links. Does the "digest mode" ...
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23 views

who has loaded an identity mapped page table?

I want to understand Linux x86_64 's startup steps, after reading some articles and linux-3.14.65/Documentation/x86/boot.txt, and almost know that the first instruction to run in vmlinux is ...
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44 views

m2c : Command not found

I want to experiment on DCTCP protocol. For that I am trying to compile linux kernel version 3.2.18 and include a dctcp patch for that. I am following the directions given here. While I am compiling ...
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31 views

minimum time between two consecutive UDP packets

I am interested in developing a C application which sends UDP packets with minimum delay between two consecutive packets. Is it possible to "book" the UDP stack with the NIC hardware from user space ...
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1answer
40 views

How to upgrade from Fedora 21 to higher stable version with the highest convenience and safety?

I am still working on a Fedora 21 Linux. I know Fedora 22, 23 and 24 already are around. However being a newbie in Linux systems and given the fact that my friend helped me to install Fedora 21 back ...
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1answer
74 views

How do I enable memory zone reclaim mode on the Linux kernel?

I am running Gentoo Linux Hardened using kernel 4.3.3-hardened-r4 on an AMD A4-5300 APU. To troubleshoot a memory problem I have with my system I need to enable sysctl vm.zone_reclaim_mode=1, but ...
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87 views

Show kernel routing exception entries (FIB)

Linux 3.6 removed the ipv4 routing cache (commit). Changelog says: Remove the ipv4 routing cache. Now lookups go directly into the FIB trie and use prebuilt routes cached there. According to ...
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3answers
475 views

I need a specific kernel version. How do I get the corresponding Debian iso?

Say I need a Debian with Kernel 3.2.63-2+deb7u1 i686. How do I find the corresponding Debian Version? I assume it would be Debian 7 because this document states that Debian 7 has Kernel version 3.2. ...
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34 views

How the file “.vmlinux.lds.cmd” is produced?

Recently, I want to know how vmlinux.lds is produced, I found a file called .vmlinux.lds.cmd which has: cmd_arch/x86/kernel/vmlinux.lds := gcc -E -Wp,-MD,arch/x86/kernel/.vmlinux.lds.d -nostdinc -...
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1answer
259 views

How to compile kernel module for different kernel version?

I have the following kernel installed: [root@localhost ~]# uname -r 2.6.32-573.el6.x86_64 And the following kernel source: linux-2.6.32-573.1.1.el6.x86_64 I am trying to compile a kernel module ...
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Can I install a .vmlinuz-<version>.hmac for an installed kernel after the fact?

I installed a kernel from elrepo on my asus ux501jw, centos7 os. I have tried the 4.5.0 and the 4.4.6 versions. Both of them do not install the hmac file /boot/.vmlinuz-.hmac file. Concequently the ...
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Install GUI :Red Hat Enterprise Linux Server release 7.0 (Maipo)

I am trying to install GUI of Red Hat Enterprise Linux Server release 7.0 (Maipo) as i follow this web page install-gnome-gui-on-rhel-7-linux-server to install GUI but when i run first command ...
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1answer
162 views

Avoiding a buggy kernel version with “Oops” in radeon module

I have exactly the same problem as described here. I can find the same "Oops" messages in /var/log/kern.log. I also have an older Radeon HD (so I have to use the free driver). I downloaded the current ...
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0answers
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cpupower can't be unable to call hardware when it tries to get the current cpu frequency

I tried cpupower on Archlinux, but it always was unable to call hardware when it tries to get the current cpu frequency. # cpupower frequncy-info analyzing CPU 0: driver: intel_pstate CPUs which ...
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Error occured with USB modem

I have MPC8309 Tower Board and connected USB Modem to it and then established Async PPP on Modem, now I started applying ping from different terminal from my laptop by applying nat commands and ...
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0answers
31 views

Invalid module format

I try to install a module using this command: sudo insmod mymod.ko [arg1] [arg2] but I get this error while loading the module: insmod: error inserting 'mymod.ko': -1 Invalid module format my ...
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1answer
38 views

iptables REJECT icmp-admin-prohibited

The iptables man page says: Using icmp-admin-prohibited with kernels that do not support it will result in a plain DROP instead of REJECT I have been unsuccessful at finding out at which kernel ...
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Linux kernel root= parameter

I'm trying to make a portable distro of linux on a 16MB SD card. I have a 2.4 kernel and extlinux as a bootloader. How can I pass the root= parameter to the kernel that the distro would be still ...
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Intermediate programmer seeks comprehensible info on which blobs are included in the Linux kernel, 4.2

I am specifically asking about the kernel included in Ubuntu 15.10 and my technical skills are meek-I can code in C, make system calls, use XCB. I barely know make, don't comprehend GIT. I cannot ...
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42 views

How to let kernel not run the printk with KERN_DEBUG

I noticed that kernel has different console levels for the printk. I also noticed this post [1]. I understand that we can change the /proc/sys/kernel/printk to change the printk level for the ...
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33 views

How to trace the life cycle of kernel threads by following creation and switching?

How to trace the life cycle of kernel threads by following creation and switching ? kernel_thread() and schedule() are the 2 functions I know that but have no idea how to implement it..
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0answers
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Cannot create 16-bit LDT segments on kernel 3.8.11

Running Crossover, I get the warning, Your system does not allow creation of 16-bit LDT segments. I am aware that this was a problem around kernel 3.1.x, but I am on 3.8.11. Also, the fix suggested in ...
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2answers
118 views

How to get the absolute position (x, y coordinates) of a finger on a touchpad?

Main question: How to get the absolute finger position on the touchpad? I would like to get the absolute position (x, y coordinates) of a finger on a touchpad? I believe it is possible to extract it ...
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0answers
76 views

what exactly is the role of device driver in the bluetooth stack (bluez or bluedroid)

I have a bluetooth USB dongle and I wish to get a grasp of what the USB device driver that will be assigned to the bluetooth USB dongle will do and which part of the bluetooth stack it will cover. I ...
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142 views

using cpu.cfs_quota_us and cpu.cfs_period_us to limit CPU usage

There are 32 cores in a system (2 cpus each 16 cores) and I want to limit a user to use only 4 cores (100% usage for that 4 cores). There are two kernel parameter for that according to the manuals: ...
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How to call a device's power management methods in another way than during suspend to ram?

Let us consider the e1000e driver for an Ethernet card. This driver provide two power management methods .suspend and .resume to respectively turn off and turn on the card. Those methods are naturally ...
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47 views

Virtual serial ports /dev/pts

I'm trying to create virtual ports using GSM cmux. It creates virtual ports in /dev/chn 1 2 & 3. Which is linked to /dev/pts 0 1 & 2. But when I list dev directory there is no pts folder and ...
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1answer
102 views

Why do the Linux kernel headers contain references to nonexistent headers?

I'm trying to build IBCS (source here) on Ubuntu 15.10 (Linux 4.2.35). This module is obviously pretty old, because its CONFIG.i386 file gives gcc an option -m486, which doesn't exist anymore, but ...
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3answers
356 views

Do tmpfs and devtmpfs share the same memory region?

My system disk usage is like this: # df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/rhel-root 50G 39G 12G 77% / devtmpfs 5.8G 0 5.8G 0% /dev ...
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1answer
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How to map Linux hard drive identifiers like “sd 3:0:0:0:” to ones like “ata8:”? [duplicate]

In my kernel log, I can see entries like: [ 0.765510] sd 3:0:0:0: [sdb] 3907029168 512-byte logical blocks: (2.00 TB/1.81 TiB) and when something fails, it's usually something like: [ ...