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

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File (products) of a kernel cross compilation

When the kernel is cross compiled (example. make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi-), what are the newly created files and their meanings? I'm not looking for a detailed explanation of each ...
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How can I compile minix when I make changes in libraries

I am looking for a way to compile minix. The make hdboot command seems to do nothing with the directories under /usr/src/lib. I changed only one .c file in syslib. Do I have to do make world for this ...
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Fedora 14 root missing capability

I am trying to run a process that performs a clone() operation using a set of flags (CLONE_NEWIPC, CLONE_NEWNET, ...) that require CAP_SYS_ADMIN capability. This should not be a problem since I am ...
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1answer
258 views

“unknown partition table” - misconfigured kernel

I was compiling a custom linux kernel for a newly installed machine, and after booting into the new kernel (3.12), the init process fails to find a root device, which I traced to the system getting an ...
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USB disk doesn't work on the new kernel

I just install the latest linux kernel (3.12.6) on my laptop(Lenovo). My system is Ubuntu 12.04. I just use the old configuration file in the old system which is "config-3.2.0-58-generic". Everything ...
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API with no system calls

The book 'Understanding Linux Kernel' says that 'for something abstract such as math functions, there may be no reason to make system calls'. Can any one please explain how is a system call not ...
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3k views

mount.cifs : mount error(12) : Cannot allocate memory

I encountered this problem a while ago when upgrading my kernel but put off upgrading until now. On my system I can happily mount network shares using CIFS running kernel 3.7.10, however when I've ...
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49 views

What software allows the change of runtime-environment, while keeping the same kernel running?

I know that with a GNU/Linux distribution you can switch between different distributions at runtime when they use the same kernel or the kernel is compatible between 2 or more different distributions; ...
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Location of the kernel binary (when not in /boot)?

I failed to find the kernel binary in the standard location in /boot. I've also searched the whole file system for vmlinux or bzimage find / -iname vmlin* find / -iname bzimage However, this is an ...
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258 views

GRUB2 Insert additional kernel modules

GRUB2 doesn't have the menu.lst file. How do I configure a boot script. During boot, I hit E on the kernel image that I want to modify and make my modifications. But I would prefer to make the ...
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340 views

What would I get when sudo a kernel-destructive program?

It suddenly comes to me how easy it will be for a sudoer to crash the kernel, so I tried something like this: #include<stdio.h> int main(){ printf("hello world"); int a; ...
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158 views

What is the maximum allowed number of TTY, is it defined anywhere in kernel headers?

What's the maximum allowed number of TTYs? I found pty.max, but is there anything similar for TTYs? Or is it defined as a fixed value in kernel headers, I couldn't find that
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945 views

After upgrading the kernel, the sound no longer works

I have updated the Linux kernel on my system to Linux 3.11-2-amd64 #1 SMP Debian 3.11.10-1 (2013-12-04) x86_64 GNU/Linux. Having done that, the sound no longer works. Distribution Info(cat ...
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191 views

How can I run gdb in one machine and run kgdb kernel in another machine?

I want to run two machine: debugged machine: compiled kernel with kgdb option. debugger machine: for running gdb How can I debug machine 1 from machine 2?
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How to fake a filesystem that cannot be mounted by others

I'm currently working on a project. There's an Ubuntu Linux system installed on a disk, DA, mounting the other disk, DB. What it requires is that DB can be only mounted by DA in order to prevent data ...
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234 views

what's the format spec for `ss -D `?

Background of the question: I am trying to sum up the total bandwidth, but ss -i cleverly converted numbers to more readable format like Kbps/s or Mbps/s, which is not accurate. So does ss -o with ...
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HDD indicator blinks when I run out of memory, but I have no swap configured [duplicate]

I'm running Arch Linux, with 8 GB memory and no swap defined. Sometimes it ran out of memory, then my system get a little bit stuck, and I can see the HDD indicator blinking. Then I restart X, which ...
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4answers
560 views

Is it necessary to reboot after a kernel upgrade (via APT)?

I have been wondering this for quite a while. Let's say that you have a Debian server that you keep updated via APT. Usually (every 1-2 months) there are some kernel updates, which will update the ...
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Qemu: No file system could mount root (unable to mount roofs)

In Linux, I've created the root file system (rootfs) by following commands: dd if=/dev/zero of=ramdisk.img bs=1M count=4 mkfs.ext2 ramdisk.img sudo mount -o loop ramdisk.img rootfs sudo cp init ...
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Kernel IPsec SA database: FIFO instead of LIFO

When processing an IP packet, the kernel looks into the security policy (SP) database to determine whether it is to be protected with IPsec. If the identifiers of the packet (e.g. IP addresses, etc.) ...
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1k views

Given a kernel ATA exception, how to determine which physical disk is affected?

I woke up this morning to a notification email with some rather disturbing system log entries. Dec 2 04:27:01 yeono kernel: [459438.816058] ata2.00: exception Emask 0x0 SAct 0xf SErr 0x0 action 0x6 ...
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when update kernels do they close bugs?

I'm not an expert in linux but when I upgrade my kernel to latest stable one which is 3.12.2, does it close all security bugs? How linux security bugs be closed? by installing newer kernel or how ...
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Capturing key input from events device and mapping it (toggle TouchPad key is unmapped)

I have a Lenovo IdeaPad Yoga 13 with Ubuntu 13.10 Installed. The device has a "Toggle TouchPad" button on the keyboard (F5). The keyboard's F* buttons are reversed (so to get F5, I need to press Fn + ...
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Where in the linux kernel sources can I find a list of the different keyboard scancodes?

I was looking for a list of keyboard scancodes in the linux kernel sources, but I did not find anything. Does someone know where to find these? Especially the USB scancodes would be interesting.
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Mainline kernel supported Raspberry Pi competitor? (no GPU needed)

The Raspberry Pi uses its own kernel fork. For a headless server (no GPU needed), is there a device with similar specs, performance-wise, that can use the vanilla mainline kernel from kernel.org?
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Debian driver needed for Intel ICH7M SouthBridge I/O controller

I am using a motherboard based on this architecture. http://www.intel.com/content/www/us/en/intelligent-systems/navy-pier/embedded-intel-atom-n270-with-mobile-intel-945gse-express-chipset.html I ...
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Doubt when compiling USB/IP drivers

I need to install a USB 3G modem to a Windows virtual machine (running on OVM). The modem will be plugged on a Linux host. (Would Windows be easier?) I don't understand what the following README file ...
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PPPD hangs, running over console port

I am trying to run the PPP daemon on the console port of my board which has p2020 processor with Linux kernel 2.6.32. After running ppp interface ppp0 is not coming up and I get an error pppd blocked ...
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154 views

How to measure PCI-Express bus usage?

I'm looking for a way to find out if PCIe bus is the bottleneck or not. It's not a problem to measure how much bytes was transferred through any particular NIC: Is there a way to find how much ...
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1k views

bnx2: Can't load firmware file “bnx2/bnx2-mips-09-6.2.1b.fw”

I just compile the kernel 3.10.19 from kernel.org Support for bnx2 is enable. On my server when I try to start the eth0 interface I got the following error : bnx2: Can't load firmware file ...
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If computers start counting at 0, why does the init process have a pid of 1?

Not much to put here in the body, the question is self explanatory.
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what is a Kernel? [closed]

I'm learning Unix from the Unix Architecture book by Maurice J Bach. So if my question seems too stupid, please do bear with it. I read a few related questions but I would like a more simple ...
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431 views

CentOS 6.4 Kickstart bootloader problem

I am installing CentOS 6.4 via a kick start file that looks like this in my build: # install the bootloader (GRUB) bootloader --location=mbr --driveorder=sda --append="crashkernel=auto" After the ...
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I/O brings a machine to its knees [closed]

Why, on every Linux I've used, when a program is really I/O bound, it bogs the machine down? It just happened when I (accidentally) tried to make gcc compile a (valid!) 50Mb C file. GCC was so I/O ...
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579 views

“Kernel panic - not syncing” after building Centos-6/elrepo 3.10.19 kernel from source

I need to rebuild the Centos-6 / elrepo 3.10.19 kernel from source. Background: the GVision touch screen drivers are incompatible with kernels > 3.8 and require source code patches to add code to ...
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How do I enable kernel option MMC_UNSAFE_RESUME

I am trying sleep and wake up my Kobo Mini ebook reader manually by using the command rtcwake. The reader is using busybox. cat /proc/version gives me this output: Linux version 2.6.35.3-850-gbc67621+ ...
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auditctl reports “File system watches not supported” on a very old system

When I run auditctl -l I got: # auditctl -l No rules File system watches not supported And I've already have AUDITSYSCALL enable in kernel, # zgrep AUDIT /proc/config.gz CONFIG_AUDIT_ARCH=y ...
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72 views

What kernel for ARM architechture, Linux or BSD? [closed]

I'm a computer sciences student and recently started a project with the engineering department that involves an onboard ARM processor, the question is what sort of operating system, kernel and ...
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417 views

How can I check my kernel preemption configuration?

I want to check if my Linux kernel is preemptive or non-preemptive. How can I check this using a command, something such as uname -a?
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Can the kernel be moved to a different mtd while the system is running?

I am attempting to do a full update on a mobile Linux Arm device. I have successfully pivoted my file system root and have been able to flash a new file system to that mtd. What I would like to ...
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302 views

Ubuntu 12.04.1 LTS - /boot is using 98.4% of 193MB

I have a problem. I have noticed that my VPS is saying : => /boot is using 98.4% of 193MB Looks like something went wrong, doesn't it? I have tried to run dpkg -l | grep linux to check what's ...
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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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What is the language that appears on the first line of a script? [duplicate]

Bash scripts start with the following line #!/bin/bash # Rest of script below ... In bash the # character is the start of a comment, but #!/bin/bash is definitely not a comment, therefore it isn't ...
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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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Can I list the filesystems a running kernel can support?

I'm trying to detect what filesystems a kernel can support. Ideally in a little list of their names but I'll take anything you've got. Note that I don't mean the current filesystems in use, just ones ...
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2k views

Building example device driver error: insmod invalid module format

I am following the tutorial @ http://www.embeddedsystemonline.com/home/embedded-system/embedded_linux/lab3-linux-device-driver on step #7 of this tutorial, $ cd ...
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Suse nVidia Driver Problems on 650M + Intel i915

Has anyone succesfully gotten the proprietary nVidia drivers to work on a system with a GT650M and an integrated Intel GPU? I don't need graphics switching, just the discrete GPU. (This is on a ...
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Enabling GPIO in kernel not working

I have tried to enable the GPIO pins for my system through the Kernel but I am not able to get them to work. When I try this: echo 1 > /sys/class/gpio/export The terminal window just closes. ...
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249 views

“kernel driver” in “lspci” output

I often use lspci -v to check the LKM in use for particular hardware device. LKMs are listed as "Kernel modules" and can be seen with lsmod. However, what is a "Kernel driver"? For example here: Is ...
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How much RAM does the kernel use?

This question is motivated by my shock when I discovered that Mac OS X kernel uses 750MB of RAM. I have been using Linux for 20 years, and I always "knew" that the kernel RAM usage is dwarfed by X ...