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

learn more… | top users | synonyms

266
votes
7answers
23k views

Understanding the Linux kernel source

I am trying to understand how a function, say mkdir, works by looking at the kernel source. This is an attempt to understand the kernel internals and navigate between various functions. I know mkdir ...
23
votes
7answers
13k views

Linux Kernel: Good beginners' tutorial

I'm interested in modifying the kernel internals, applying patches, handling device drivers and modules, for my own personal fun. Is there a comprehensive resource for kernel hacking, intended for ...
9
votes
3answers
241 views

kernel: Namespaces support

I am wondering what exactly the “Namespaces support” feature in the Linux kernel means. I am using kernel 3.11.1 (the newest stable kernel at this time). If I decide to disable it, will I notice any ...
13
votes
3answers
9k views

Linux: How to find the device driver used for a device?

If my target has one device connected and many drivers for that device loaded, how can I understand what device is using which driver?
11
votes
3answers
1k views

Given a git patch id, how to find out which kernel release contains it?

Assume I have some issue that was fixed by a recent patch to the official Linux git repository. I have a work around, but I’d like to undo it when a release happens that contains my the fix. I know ...
7
votes
2answers
201 views

Strange temporary network outage in Linux

I'm facing a very annoying problem that I noticed a week from now and for which I can't find an answer: my network suddenly stops responding, usually coming back exactly 25 seconds later. I was using ...
5
votes
1answer
422 views

What are the main differences between Unix and Linux kernels today?

I know that many of the same programs run flawlessly on top of both kernels. I know that historically, the two kernels came from different origins. I know philosophically too that they stood for ...
5
votes
1answer
114 views

Linux: What is a tainted kernel?

Under certain conditions, the Linux kernel may become tainted. For example, loading a proprietary video driver into the kernel taints the kernel. This condition may be visible in system logs, kernel ...
3
votes
2answers
6k views

What does “INFO: task XXX blocked for more than 120 seconds” exactly mean on Linux?

I had this message in my kernel log : INFO: task XXX blocked for more than 120 seconds. I would like to know what it means technically: under what conditions does the kernel display this message about ...
3
votes
2answers
1k views

Linux kernel is not finding the initrd correctly

I had compiled a linux kernel and I wanted to debug it in QEMU. I created a file to boot from by doing the commands $ qemu-img create -f raw disk.img 200M $ mkfs.ext2 -F disk.img # mkdir /mnt/rootfs ...
2
votes
1answer
853 views

Running bzImage in QEMU

I compiled the kernel by doing make menuconfig and make. I was trying to run the bzImage in qemu, by doing qemu -kernel bzImage but it didn't work out: How can I fix it? How can I run the bzImage ...
0
votes
2answers
748 views

After removing linux Grub error

I have a dual boot Windows & Linux system. I removed the Linux partition, but after that I am not able to go in to Windows XP. It is not booting. It gives me a GRUB error.
-2
votes
2answers
560 views

Entry point of linux kernel [closed]

In the linux kernel is there a file that I can start to add my code, ex. load libraries? thanks
7
votes
1answer
12k views

Enabling IOMMU in the kernel for graphics card pass-through

Short question: How can I turn on the intel_iommu setting in the Linux kernel? I run a Debian host, using the grub2 bootloader. Documentation I've seen says to edit /boot/grub/menu.lst, which seems ...
23
votes
1answer
2k views

High CPU usage with CFS?

I asked a previous question to try and isolate the source of an increase in CPU usage when moving an application from RHEL 5 to RHEL 6. The analysis that I did for that seems to indicate that it is ...
11
votes
3answers
678 views

How to tell Linux Kernel > 3.0 to completely ignore a failing disk?

I am asking this question here in the hope that some Linux-kernel guru can have an answer. This question has been asked on AskUbuntu and on SuperUser without answers: thinking better, it is really ...
7
votes
1answer
298 views

How is nice working?

sched_setscheduler says : All scheduling is preemptive: if a process with a higher static priority becomes ready to run, the currently running process will be preempted and ...
5
votes
2answers
294 views

mount options shown in /proc/mounts

IIRC then the mount options shown in /proc/mounts have changed. Some time ago acl and user_xattr were shown, now it seems that only noacl and nouser_xattr are shown if these features are turned off. ...
14
votes
2answers
1k views

The UEFI & SecureBoot impact, how severe?

I'm planning to buy a new laptop in the coming days, and I'm quite impressed with new, cool Ultrabooks. As a long-time GNU/Linux user, I'll of course install a distro of my choice on it. Chances are ...
6
votes
1answer
2k views

Load Linux bzImage in QEMU?

I compiled a Linux by doing make menuconfig then make and now I have compiled the most recent version of Linux. How can I load the kernel into QEMU?
8
votes
1answer
3k views

Isolating cause of higher CPU usage on RHEL 6 vs RHEL 5

I'm currently looking to move our system from RHEL 5 to RHEL 6, but I've run into a snag with unexpectedly high CPU usage on the RHEL 6 machines. It appears that this may be due at least in some part ...
5
votes
4answers
2k views

Are FIFO, pipe & Unix domain socket the same thing in Linux kernel?

I heard that FIFOs are named pipes. And they have exactly the same semantics. On the other hand, I think Unix domain socket is quite similar to pipe (although I've never made use of it). So I wonder ...
5
votes
2answers
790 views

How is a Linux kernel capable of accessing its assigned initramfs/initrd?

I'm trying to understand the boot process of a machine as a whole from the time you hit the power button. There's this one piece from bootloader to initramfs stage I don't quite understand among some ...
5
votes
1answer
3k views

Why does Linux show both more and less memory than I physically have installed?

I know about swap - this question isn't about that. In dmesg, the Linux (x86-64) kernel tells me this about how much memory I have: [ 0.000000] Memory: 3890880k/4915200k available (6073k kernel ...
3
votes
2answers
251 views

How can I know if the current kernel was compiled with a certain option enabled?

Is there a way to know if the kernel was compiled with a certain option activated (i.e. CONFIG_PROC_EVENTS=y) without having to pull out the kernel sources package and looking in the config file?
3
votes
1answer
1k views

Is it possible to run any distro from RAM from within an .iso saved on an NTFS file system?

Running entirely from RAM been done on various distros such as Slax, DamnSmallLinux, and newer Ubuntu versions, and since I have 8GB it seems reasonable that I could run many distros entirely from RAM ...
2
votes
1answer
261 views

Compile the Ubuntu “Raring” Kernel with the Intel Compiler

Of course, the first question is: why I'm doing this. Just for fun! I'm learning more about Linux kernels and I have a virtual machine that I can replace in 15 minutes. Getting to business, I don't ...
2
votes
1answer
224 views

Address types used in Linux

I am trying to understand the Memory address types used by the Linux kernel, which are User virtual address Physical address Bus address Kernel logical address Kernel virtual address I understood ...
2
votes
1answer
1k views

Unpacking kernel-source rpm off-system (OpenSuse)?

I'm using OpenSuse 11.2 from a LiveUSB USB flash/stick, which arguably has not much place on it. I need to get the Linux sources for this version of OpenSuse, as they are needed to build a driver for ...
6
votes
2answers
1k views

An oom killer thats baffling me

I am not able to understand why would kernel issue this oom killer when I see enough memory is available: Also why are there so many kernel cache pages allocated? I say enough memory is available ...
3
votes
2answers
763 views

Where can I find the Linux driver for headphones in the kernel tree?

I have headphones with three buttons on them which allow me to control my music player with my phone. I want to write a driver for my headphones to make it control my music player on my pc (Ubuntu ...
2
votes
2answers
77 views

What is the difference between a patch which reverts a commit and a “reversed patch”?

Before May 6th, 2013, the fs/eventpoll.c file in the Linux kernel had the following line #1605: if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS)) On May 6th, a commit changes this to ...
1
vote
3answers
53 views

Enabling IP forwarding at kernel compile time

I am compiling a kernel for a router. I know a way to enable IP forwarding in an existing Linux system. At compile time, CONFIG_IP_FORWARD is said to do the same task. I am configuring version ...
1
vote
1answer
170 views

system went unresponsive and had to hard reboot

without not much load on the machine, it suddenly went busy and went unresponsive. it could not respond to keyboard or mouse movement or neither would move to another other tty's. there is some log ...
1
vote
2answers
817 views

Running Linux kernel in Virtualbox

I just built a Linux kernel on Ubuntu and now I want to make it run on VirtualBox. I wanted it to be in an img format. I created a hard drive image by doing the commands: $ qemu-img create disk.img ...
1
vote
2answers
195 views

loading python when the linux kernel boots

I was reading This and I was wondering if I could write an API in python or have python load in an init script. If this were to be possible would I need to edit the kernel's makefile?
0
votes
1answer
404 views

OS errors : kernel: EDAC k8 MC0: extended error code: ECC chipkill x4 [duplicate]

We noticed the server crashes with below errors. Not sure it is related to any defected piece of the hardware or totally not related to Server detail:Red Hat Enterprise Linux ES release 4 (Nahant ...