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

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3answers
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Rings and run levels

The question stated below might not be technically correct(misconception) so it would be appreciable if misconception is also addressed. Which ring level do the different *nix run levels operate in? ...
0
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1answer
75 views

How do I verify that the Linux kernel is not freezing when uploading or downloading large data over the ethernet interface?

How to verify if the Linux kernel is doing what it's saying for network interfaces? I have one network interface eth0 which has hardware support to do 1GB full-duplex. I have prepared 2 box. Now ...
3
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2answers
218 views

Why do people call Linux a kernel rather than an OS?

Why do people refer to Linux as a kernel rather than an operating system? To the best of my knowledge, the kernel is one part of the operating system.
1
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1answer
112 views

Kernel pppd task hung after running over serial 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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2answers
950 views

error: “net.inet.ip.fastforwarding” is an unknown key

I've been doing some research into improving performance for OpenVPN and I found out about setting fastforwarding to 1 but when I tried I got the error error: "net.inet.ip.fastforwarding" is an ...
1
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1answer
42 views

Why have a fake LR-WPAN driver?

In the Linux kernel configuration, a fake LR-WPAN driver can be enabled and added to the kernel that will be compiled. Why would someone want a fake LR-WPAN driver? I assume it would be for debugging, ...
6
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2answers
185 views

Are the outputs of /proc/meminfo, /proc/cpuinfo etc always in English?

I am writing code that relies on the output of /proc/meminfo, /proc/cpuinfo etc. Are the file contents always in English? For example, will MemTotal in /proc/meminfo always be MemTotal in all locales? ...
2
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1answer
519 views

How can I install Arch Linux on a Laptop with Intel GMA 4500 MHD?

I would like to install Arch Linux on my Acer TravelMate 5735Z. Sadly, it has a Intel GMA 4500 MHD graphic card. This means, I suffer from Kernel Bug [GM45] black screen at boot (0 backlight?). When ...
4
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1answer
65 views

Is there any difference between these two configuration options?

Is there any actual difference between iptables -P FORWARD DROP and net.ipv4.ip_forward = 0 ? I know that one is a firewall command while the other one is a kernel option. But: I don't know ...
0
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3answers
283 views

Kernel panic after building kernel in Red Hat Linux?

I've been trying to build a new kernel for Red Hat Enterprise Linux virtual installs under VM Ware. I've followed these steps so far: Download the kernel from kernel.org. Extract the downloaded ...
4
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1answer
117 views

why would there be a load of 5 if there are zero processes in the runq?

This doesn't make sense to me, why would there be a load of 5 if there are zero processes in the runq? 12:00:01 AM runq-sz plist-sz ldavg-1 ldavg-5 ldavg-15 12:05:01 AM 0 708 ...
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1answer
301 views

How to specify an ISO as the location of root filesystem for GRUB?

I'm trying to understand the Debian "booting from Hard Disk" installation manual. The process is as follows: I copy a kernel image, a ramdisk initrd and an ISO with installer to the hard drive and ...
1
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1answer
53 views

How can I compile, install and run the tools inside kernel/tools?

There are some tools in side the kernel, <kernel source root directory>/tools perf is one of them. In ubuntu I think the tools inside this folder is available as package linux-tools How ...
3
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1answer
418 views

What happened to `vga=ask` in newer kernels?

I used to activate framebuffer mode in the "older" kernels with vga=ask, and later setting it to a value, once I've figured out which one works best for me. Now, this option seems to be gone, the ...
0
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1answer
69 views

Could the Kernel stack of a process be empty, when a process is swapped out to a disk?

I am just curious to know whether the Kernel stack could be empty when a process is swapped out to a disk or not?
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6answers
2k views

Can Linux “run out of RAM”?

I saw several posts around the web of people apparently complaining about a hosted VPS unexpectedly killing processes because they used too much RAM. How is this possible? I thought all modern OS' ...
0
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1answer
459 views

How can I install perf 3.4.25?

By installing perf using sudo apt-get install linux-tools-common sudo apt-get install linux-tools-3.2.0.23 gave me perf version 3.2.14 How can I install perf 3.4.25? Is it related to kernel ...
3
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1answer
238 views

ACPI Errors/Exeptions, why they spam, how to know and fix it?

I've been having these errors pollute my dmesg: [21720.400079] ACPI Error: [\_TZ_.THRM] Namespace lookup failure, AE_NOT_FOUND (20130328/psargs-359) [21720.400093] ACPI Error: Method parse/execution ...
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2answers
1k views

Linux Mint Debian quits on boot

I just upgraded Linux Mint Debian Edition with the up7 package. The update manager failed initially (can't remember where...) so I ran sudo apt update, sudo apt dist-upgrade, sudo apt upgrade and ...
3
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2answers
143 views

Linux process “scheduling”

I've seen it written many times that the Linux scheduler schedules processes. I'm teaching a course on multithreaded programming, and would like to get my terminology straight. I have one thing I ...
2
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0answers
224 views

TUN/TAP Will not load

I have an OpenVZ server but can't seem to get the tun/tap module to load. I ran modprode tun on the hostnode but when I go under the VM I get: Tue Sep 24 03:08:36 2013 Note: Cannot open TUN/TAP dev ...
0
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1answer
82 views

Confusion with Linux kernel [closed]

I am really confused with the kernel concepts. I came to know that the kernel is between application and hardware, and that the kernel takes input from the applications and it will send the ...
29
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2answers
1k views

What's the difference between a kernel oops and a kernel panic?

I know what a kernel panic is, but I've also seen the term "kernel oops". I'd always thought they were the same, but maybe not. So: What is a kernel oops, and how is it different from a kernel panic? ...
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1answer
2k views

How to fix unreliable Realtek Wireless card on Ubuntu 13.04

I have a Realtek RTL8188CE wireless card and it works fine when I have a strong signal, but if I get even slightly away from the wifi I lose connectivity even though there is a strong Rx signal. I ...
4
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1answer
162 views

What changed between kernels 3.2 and 3.9 that affect MiniDLNA?

I'm using Debian testing, and I've problems with MiniDLNA on kernel > 3.2. The DLNA client works about 30 min, after that it lost the connection with the minidlna server and can't discover the server ...
2
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1answer
582 views

Features that Linux kernel has and Windows does not? [closed]

What are the significant technical features the Linux kernel has that the Windows does not? Something that I might find on a kernel feature list, which is conceptually an advantage, or significantly ...
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2answers
61 views

Is there kernel patch to prevent load files into RAM for LiveCD?

Is there kernel patch to prevent load files into RAM for LiveCD? I mean, if I'm use LiveCD with "boot to Ram" option, there is no needs for kernel to load executable binaries to RAM from RAM. It ...
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2answers
250 views

Linux kernel with absolutely no virtual memory [duplicate]

I am interested in obtaining (or building myself) a version of the Linux kernel that has absolutely no virtual memory and none of its attendant overhead. No swap file, no nothing. What are my ...
2
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1answer
89 views

Server pinning one core

I'm working on a server using Vert.x in Java and I'm noticing some performance problems when running on a dedicated server running Ubuntu 12.04. The server picks up the incoming HTTP requests, does ...
3
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1answer
656 views

How can a user run a program in kernel mode?

Is it possible for a user to run their own program in kernel mode? How could a user accomplish this? What weakness in the system's protection mechanism would they have to bypass? I'm thinking that a ...
9
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2answers
7k views

How to disable USB autosuspend on kernel 3.7.10 or above?

I've updated my HTPC from kernel 3.7.10 to 3.10.7 and it seems CONFIG_USB_SUSPEND is now gone from the kernel options and included in PM. The main problem I'm facing is that I have an external HDD ...
4
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2answers
161 views

What does it mean to install a kernel?

What does it mean to install a new version of the kernel. My Linux box gave me this message when I was updating, NOTE, 3.8.13 was the last maintained maintenance release by Greg Kroah-Hartman. ...
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2answers
162 views

Why should I build a custom kernel? [closed]

Several of my coworkers have been building custom kernels for their workstations and servers. What advantages/disadvantages are there to building a custom kernel? Why should I build a custom kernel? ...
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vote
1answer
123 views

Using qemu to boot OpenSUSE (or any other OS) with custom kernel

I want to run OpenSUSE as guest with a custom kernel image which is on my host machine. I'm trying: $ qemu-system-x86_64 -hda opensuse.img -m 512 -kernel \ ...
4
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2answers
2k views

How does Linux load the 'initrd' image?

I've been trying to understand the booting process, but there's just one thing that is going over my head.. As soon as the Linux kernel has been booted and the root file system (/) mounted, ...
45
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5answers
2k views

How to compile the C compiler from scratch, then compile Unix/Linux from scratch

Let's say I work for a large services organisation outside the US/UK. We use UNIX and Linux servers extensively. Reading through this article it mentions that it would be easy to insert a backdoor ...
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2answers
360 views

Kernel freezes on loading ramdisk. How to find out what's wrong?

I'm using an Ubuntu Server (13.04) Minimal installation (with the Xubuntu Metapackage as a desktop environment, if that matters) on x86_64 on my Samsung notebook. I'm currently forced to use the ...
105
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3answers
7k views

What does the Windows flag in the Linux logo of kernel 3.11 mean?

I've just installed kernel-3.11.0-1.fc20 for my Fedora 19 installation. During the rebooting progress, I saw the Linux logo with a Windows flag in it, what does it mean? The Fedora 19 is installed ...
2
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3answers
866 views

Boot my kernel in a Virtual Machine?

I'm learning now how to compile and boot linux kernels. Is there a way to boot kernels in a virtual machine, rather than messing my system? I use VMWare Workstation on Windows 8. Can I use that to ...
2
votes
1answer
314 views

Some keys keep getting randomnly ignored when typing on my laptop keyboard

Currently, I have Arch Linux 64-bit installed on the Razer Blade Pro laptop. The only problem I have is that some keystrokes get randomly ignored when typing at normal-fast speed (above 5 keys/sec ...
6
votes
2answers
897 views

/proc/sys vs /sys/modules/mod/parameter

I've been wondering for last few days how exactly does it work. We can set kernel runtimes parameters using sysctl or echo boolen 1> /proc/sys/module/exactParameter but in ...
16
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2answers
9k views

Why is swappiness set to 60 by default?

I just read some stuff about swappiness on Linux. I don't understand why the default is set to 60. According to me this parameter should be set to 10 in order to reduce swap. Swap is on my hard ...
0
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1answer
78 views

init 0 process is not starting

Yesterday I have encountered one problem, when I turn on my PC it took a long time to boot. After booting it reached to command line with <initramfs> (It is unknown to me what it is) I thought ...
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2answers
52 views

Find or create kernel configuration of kernel binary

I've downloaded a kernel binary which I am using now. In order to use the watchdog on my system I must recompile the kernel with watchdog support. Is it possible to obtain the current kernel ...
1
vote
1answer
228 views

Kernel module blacklist not working

I'm trying to figure out how to blacklist modules, and I'm trying it on the usb storage. Unfortunatelly it seems ot have no effect, and I get the module in even if it's not used (apparently). My ...
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1answer
67 views

Booting failing in different Debian and Debian derivated distros?

I've tried Ubuntu, Linux Mint and Debian, even though all have worked great for me I'm keeping with Ubuntu, I tested 12.04, 12.10 and even 13.04. The 12.04 LTS is the one I work with. There's one ...
22
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1answer
14k views

How do you empty the buffers and cache on a Linux system?

Prior to doing some benchmarking work how would one free up the memory (RAM) that the Linux Kernel is consuming for its buffers and cache?
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0answers
106 views

Virtual address of Global variables in Kernel code

If my understanding is not wrong, every process has a Kernel Address space associated with it (which is typically 1GB). As far as local variables are concerned, they are assigned on the kernel stack ...
16
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1answer
7k views

What is difference between User space and Kernel space?

Is Kernel space used when Kernel is executing on the behalf of the user program i.e. System Call? Or is it the address space for all the Kernel threads (for example scheduler)? If it is the first ...
2
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2answers
714 views

busybox initramfs loop mount

I'm trying to loop mount my root filesystem (a loop file) within a busybox initramfs. I try to run the command: mount /rootfs.raw /root ... which works on my Ubuntu laptop, however, I simply get ...