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

learn more… | top users | synonyms

19
votes
1answer
2k views

Configuring, compiling and installing a custom Linux kernel

I'd like to try using a kernel other than the one provided by my distro -- either from somewhere else, or as customized by me. Is this difficult or dangerous? Where do I start?
296
votes
7answers
26k views

How can I find the implementations of Linux kernel system calls?

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 ...
11
votes
3answers
1k 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 ...
5
votes
2answers
606 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. ...
31
votes
7answers
20k views

Linux Kernel: Good beginners' tutorial [closed]

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 ...
3
votes
5answers
5k views

Kernel can't find /dev/sda file during boot

I configured a gentoo kernel (kernel-2.6.36-gentoo-r5), but when I boot it can't mount /dev/sda1: ALERT! /dev/sda1 does not exist . Dropping to a shell . I use the shell to go to the /dev ...
21
votes
2answers
26k 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?
18
votes
3answers
3k 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 ...
15
votes
5answers
11k views

Is it possible to install the linux kernel alone?

I'm just curious if it's possible to install the linux kernel alone, or if you need to use one of the flavours. If it were possible, how would you do it? I don't need a detailed tutorial. I just want ...
13
votes
3answers
2k 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 ...
4
votes
4answers
5k views

cp vs. cat to copy a file

cp a b and cat a > b, what's the difference? In x86 install script of linux kernel's source tree (arch/x86/boot/install.sh), both are used: cat $2 > $4/vmlinuz cp $3 $4/System.map Why don't ...
5
votes
2answers
3k views

How to build a custom kernel? [duplicate]

I want to test an (upstream) custom kernel on Fedora. The plan so far is: use a recent fedora config as starting point, e.g. /boot/config-3.6.6-1.fc17.x86_64 lookup build dependencies lookup right ...
13
votes
1answer
6k 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 ...
7
votes
2answers
353 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 ...
6
votes
1answer
494 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 ...
4
votes
2answers
1k views

Change kernel parameters at runtime

While trying to fix an obscure hardware bug, it was suggested that adding a couple of parameters to the kernel might resolve the issue. I can of course do that, but I was wondering whether I can make ...
4
votes
3answers
14k 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 ...
6
votes
2answers
4k 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 ...
4
votes
1answer
1k 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 ...
3
votes
1answer
271 views

Which Debian kernel should I install?

I've started installing Debian testing on amd64 and I've come to a screen asking me to install a kernel. It gives me a choice between linux-image-3.16-2-amd64, linux-image-amd64, and none. What is ...
1
vote
1answer
394 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 ...
0
votes
2answers
925 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
876 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
11
votes
5answers
23k 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 ...
16
votes
6answers
4k views

Can ps display only non kernel processes on Linux?

How can I ask ps to display only user processes and not kernel threads? See this question to see what I mean...
24
votes
1answer
3k 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 ...
8
votes
1answer
1k 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 ...
11
votes
2answers
1k views

What does a niceness value of (-) mean?

According to the man page, and wikipedia; nice ranges from -20 to 20. Yet when I run the following command, I find some processes have a non numerical value such as (-). See the sixth column from ...
13
votes
1answer
8k views

Setting CPU governor to on demand or conservative

I'm struggling with cpupower on ArchLinux. I want to set governor to ondemand or even to conservative. First if I do $ sudo cpupower frequency-info --governors, I only get performance powersave. So ...
9
votes
1answer
3k 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?
15
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 ...
11
votes
4answers
7k 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 ...
7
votes
2answers
1k 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?
7
votes
2answers
3k views

How to set OOM killer adjustments for daemons permanently?

Running some Linux servers with single or just a few vital system service daemons, I would like to adjust the OOM killer for those daemonized processes in case something odd happens. For example, ...
5
votes
1answer
3k 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 ...
4
votes
3answers
982 views

How to tell of whether the kernel parameter [passed at command line] is a valid kernel parameter?

In the grub.conf configuration file I can specify command line parameters that the kernel will use, i.e.: kernel /boot/kernel-3-2-1-gentoo root=/dev/sda1 vga=791 plasticDuck After booting up a ...
3
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 ...
9
votes
1answer
4k 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 ...
8
votes
3answers
5k views

Can vmlinux be used instead of uImage?

I want to use an uncompressed kernel image and boot the BeagleBoard. Generally I use uImage to boot the kernel which is in compressed format. How do I use an uncompressed kernel image?
6
votes
2answers
302 views

Linux kernel manual build: resulting binary is 10 times larger than precompiled binaries

I'm using Linux Mint 13 MATE 32bit, I'm trying to build the kernel (primarily for experience and for fun). For now, I like to build it with the same configuration as precompiled kernel, so firstly ...
6
votes
2answers
1k 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 ...
6
votes
1answer
4k 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 ...
4
votes
3answers
331 views

System calls supported in running Kernel

Is there a way to get the number of or list of system calls supported by currently running Linux Kernel? So I want to find a way to 'read' the syscall table of a running kernel.
3
votes
1answer
2k views

How to make EDID

I read the post here and I tried to make do with what I understood from the post but here are some questions: Where is the /lib/firmware located in for example /usr/src/linux/lib/firmware or ...
3
votes
1answer
9k views

/proc/sys/kernel/hung_task_timeout_secs error

I am building a CentOS 6.2 webserver on a Hyper-V Cluster and have hit a major issue. The current setup is this: Operating System: CentOS 6.2. Minimal Server Install Installed software includes: ...
3
votes
2answers
1k 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
1answer
996 views

“Package 'linux-headers-3.13.0-27-generic' has no installation candidate”

I'm trying to resolve an issue that I posted here. I'm basically trying to successfully run this script. To do that, I believe (and I its very possible that I'm wrong) I need to install the ...
2
votes
1answer
654 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
472 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 ...
1
vote
0answers
75 views

Decreasing mouse sensitivity at kernel level

I have developed a custom-GUI Server, which runs on virtual console of Linux.For mouse-handling purpose, it reads the mouse device file /dev/input/mice and retrieves the event data and updates ...