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

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How does the Linux kernel initialize console graphics?

Observation: I switch on a Linux box Boot loader displays its output on screen Boot starts with first output messages Screen goes blank, and never comes back on. Note: this is about the console, ...
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1answer
111 views

Kernel ATA Exception after resume from suspend to RAM

After resuming from suspend to RAM, my Arch Linux system freezes and becomes permanently unresponsive. However, I managed to pull the following kernel log: kernel: sas: Enter sas_scsi_recover_host ...
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1answer
27 views

NAS: 100% system (kernel) cpu usage

I have a single core NAS My Live Duo. It runs Debian lenny release. I found via htop utility that it constantly use 100% of red cpu without any noticeable process to eat it. Than I checked via iostat ...
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2answers
290 views

Library routines in linux kernel

In the linux kernel, there is a section "Library routines" with a snippet shown below: Library routines ---> <M> CRC-CCITT functions <M> CRC ITU-T V.41 functions <M> CRC7 ...
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1answer
5k views

How to get back from “testing” to “stable” - Kernel downgrade

currently I am having lot's of fun with apt-get - and the bad thing is, it was my own fault. I had enabled the testing packages in /etc/apt/sources.list to install a certain package. And I told my ...
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Linux Kernel Version >=3.14 Obliterates Wi-Fi Dongle!

I own a TP-LINK WN725N, and any linux distro with the kernel version before 3.14 works fine, but past 3.14, the dongle cannot hold a speed of over 10 kb/s for more than 10 seconds. Reconnecting solves ...
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1answer
15k views

Kernel inotify watch limit reached

I'm currently facing a problem on a linux box where as root I have commands returning error because inotify watch limit has been reached. # tail -f /var/log/messages [...] tail: cannot watch ...
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111 views

Corrupt LVM metadata header after kernel update

I'm running Debian Wheezy (Linux wheezy3.2.0-4-amd64 #1 SMP Debian 3.2.63-2+deb7u1 x86_64 GNU/Linux) as an encrypted LVM with hardware raid 1 (Adaptec 6405E) on a supermicro server. I was encounting ...
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2answers
3k views

How to know which firmware is loaded by kernel?

I have an Intel wireless card driven by iwlwifi, and I can see the following message in dmesg: iwlwifi 0000:03:00.0: loaded firmware version 17.168.5.3 build 42301 But how do I know which firmware ...
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2answers
71 views

Log message “Disabling IRQ”: what does it mean?

This message appears in my dropdown terminal at seemingly random times when no processes is running in that terminal: andreas@debianator:~$ Message from syslogd@debianator at Feb 24 18:57:58 ... ...
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33 views

Do dracut handles boot parameters mentioned in dracut.cmdline (7)

If I understand correctly, in boot time the kernel will mount initramfs and then calls /sbin/init from it(which is a symbolic link to /lib/systemd/systemd on Fedora/RHEL systems) and dracut itself ...
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4answers
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Why some operating systems event handling is written in asm instead of c?

My question is why nowadays some operating system event handling is still written in assembly language instead of a higher level language such as C, when the kernel itself is written mostly in C?
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1answer
441 views

Can the 25 years of development of the Linux kernel be qualified or abstracted in layman's terms? [closed]

The Linux kernel is almost 25 years old. If I had to come up with the short version on the development history of the Linux kernel since 1991(its inception date), and in partcular since 1994 (1.0.0) ...
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14 views

insert module to kernel

I installed latest version of IPCOP, I've the correct module of my wireless card (htc_9271.fw): put it to /lib/firmware/ there is not any insmod/rmmod but only modprobe: modprobe htc_9271 FATAL: ...
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1answer
96 views

RTC time synchronization not working (CONFIG_RTC_SYSTOHC)

I have the option CONFIG_RTC_SYSTOHC enabled in my kernel: Device Drivers ---> [*] Real Time Clock ---> [*] Set the RTC time based on NTP synchronization The help says: ...
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34 views

Print list of bad blocks in NAND flash from user space

Is there any user space tool that can retrieve and dump the list of bad blocks in a NAND flash device? I've checked the mtdinfo command line utility, and also searched /proc and /sys, but couldn't ...
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1answer
61 views

Few questions about system calls and kernel modules (kernel services in parallel)

I have few questions about system calls and kernel modules. Let's assume we have two applications (A and B) and each of them is running on a different core. (A-CPU 0, B-CPU 1) When two applications ...
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1answer
64 views

Enabling ethernet over usb support in Linux Kernel

How to enable Ethernet over USB support in linux kernel. Which driver(like CONFIG_USB_USBNET) is related to this support. Is EEM (Ethernet Emulation) regarding this support or not..???
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18 views

Slow graphics when using kernel without module unloading support

If this is the wrong place for this question, please let me know. I didn't know where to ask, so here we go: Initially I wanted to disable module loading support for my linux kernel because I know ...
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0answers
60 views

Is it safe to disable Frequency Scaling and CPU idle Power Management support for Real Time purposes?

I'm using a Raspberry Pi board and I would like to build a real time system. During the kernel configuration, I found the CONFIG_CPU_FREQ option, which (from the help section) allows you to change ...
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1answer
396 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 ...
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174 views

update kernel without restart

Recently Linux got a new feature called Live Kernel Patching, which you means you dont have to restart your system to update kernel. Is there any other kernel which has this feature already or Linux ...
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251 views

dmesg: pci BAR 7: can't assign io

I have VMware virtual machine running Debian Wheezy. I have compiled my own kernel 3.14. I have noticed dmesg is flooded with messages pci BAR 7: can't assign io (size 0x1000). I have no idea what ...
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39 views

Boot partition was unmounted during kernel update

So, I updated the kernel from 3.18.5-Arch to 3.18.6 and without mounting my boot partition. Now, no usb device (vfat not recognized) can be mounted and no network connection (no interface except lo) ...
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7answers
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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 ...
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How to instruct RHEL6.5 Linux to save/starts states before crush or restart

I have multiple Workspaces, each responsible for different revisions of the same software. Not to have to recreate all Worspaces and open all tools/windows, I'm wondering how can I instruct Linux to ...
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2answers
40 views

Kernel panic if LUKS password is bad x times

Q: Is it normal if a RHEL 6.5 machine kernel panics if I type the LUKS password a few times wrong?
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1answer
97 views

lsof: measure I/O rate of a socket fd

I'm writing a script that parses the output of lsof to show a list of what processes have sockets open (similar to what netstat shows). lsof also gives me a file descriptor. What I want to do now is ...
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0answers
41 views

USB keyboard is disconecting automatically (without being unplugged)

In my log, I see following message: kernel: usb 1-1.6: USB disconnect, device number 5 acpid: input device has been disconnected, fd 7 acpid: input device has been disconnected, fd 8 I have not ...
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0answers
62 views

cannot locate header while making buildworld in custom kernel source

I'm trying to install a custom kernel in freebsd and here's step I followed: install freebsd 9.1 on vm from the image get the source from hardenedBSD (branch hardened/9/kernsep) execute "make ...
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47 views

Why doesn't Linux IPSec implementation support fragmentation before encryption?

I am trying to address an issue where ESP packets are getting fragmented as after adding the ESP header the MTU size is exceeded. The solution—which is what everybody does—is to do the fragmentation ...
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Kernel compilation for minimum program execution

Compiling the Kernel requires me to configure modules. I am unsure how to configure a Kernel which only supports following things: Programs compiled with gcc on other machines (glibc). I want to run ...
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1answer
53 views

What is “fs” short for in kernel function “get_fs()”?

There are two Linux kernel functions: get_ds() and get_fs() According to this article, I know ds is short for data segment. However, I cannot guess what "fs" is short for. Any explanations?
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3answers
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what is pts/0 and (:0.0) in linux by type who am i

When I type the command: [root@degeneration Desktop]# who am i root pts/0 2013-04-12 15:08 (:0.0) What is pts/0 and what is meant by (:0.0)?
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3answers
12k 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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Installing kernel headers (prior to `make install_headers`)

I'm trying to accomplish this make ARCH=x86_64 INSTALL_HDR_PATH=/opt/cross/x86_64-linux headers_install But with the 2.6.9 kernel tarball. It does not support the make target headers_install and ...
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144 views

Debian boot freeze (hard lockup)

I'm using debian sid and during two years i watch the same problem. When I boot from grub my system on the screen appears follow text: Linux kernel in decompress level...Parsing elf and then freeze ...
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2answers
153 views

How do you get hardware info and select drivers to be kept in a kernel compiled from source?

I would like to create a minimal kernel for a web server. When you compile a kernel from source how do you get hardware info and then know what drivers need to be kept in the kernel so the rest can ...
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How do kernel inform OSPF daemon when a physical interface status is down?

When a physical interface status is changed from up to down, there are 3 things related to the computer's current routing table and OSPF. The (connected) network for that interface and remote ...
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1answer
19 views

Kernel config: Is undefined the same as disabled?

Reading the Debian Kernel Handbook I came across the config option CONFIG_DEBUG_INFO. That option isn't in the official debian 3.2 kernel config, so what I'd like to know: If a certain option is not ...
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0answers
29 views

Improve kernel boot time

I am using OMAPL138 and kernel version 2.6.37 and I would like to improve the boot time. By analyzing the kernel boot process I think it is taking a long time at MII PHY CONFIGURATION. The printscreen ...
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2answers
128 views

Why is Linux “Unix-like” if its kernel is monolithic?

As I understand it, part of the Unix identity is that it has a microkernel delegating work to highly modular file processes. So why is Linux still considered "Unix-Like" if it strays from this ...
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Debugging info in linux kernel - how does it work?

I have found that I can compile linux kernel with some flags adding debugging support like CONFIG_DEBUG_INFO. These options while useful in debugging are also required by some utilities like ...
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3answers
57 views

Boot process - Dev sdX name changes

I had a Slack 13.1 machine with 2.6.36 kernel. Then, I updated the kernel to 3.12.1. This machine has connected: a bootable disk with three partions (/dev/sda1 --> Linux OS files..., /dev/sda2 --> ...
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1answer
103 views

Building a minimal linux

I have been following A Minimal Linux System from Scratch in order to build a Linux with a small footprint (10MB or less). I'm fairly certain that there were no errors up until the last point, where ...
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2answers
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How to return 0 if a pattern is matched from a file? [duplicate]

I have a binary that repacks android kernel (not mkbootimg). I'm making a script to automate the process. I don't want any output on the screen. So I have redirected the output to a file named ...
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Can I masquerade a kernel uevent?

What I think happens From my understanding this is what happens when I connect a USB device to my computer: Kernel recognizes that I plugged in a USB device Kernel setups the very low-level things ...
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2answers
6k views

Kernel Panic - not syncing: VFS: Unable to mount root fs after new kernel compile

So I've been at this for a while and have been poking around for an answer for a few days, and figure it's about time to ask for help. I am running Ubuntu 10.10 in VMWare Fusion, and have downloaded ...
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1answer
129 views

Output shutdown messages to multiple consoles

I have configured my system to direct console output on boot to serial and vga using kernel parameters. Serial is the last argument in the kernel parameters and will be the default used for ...
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0answers
644 views

Install rtl8188etv/rtl8188eu driver on Orange-Pi

I'm trying to install the wifi driver on Orange-Pi board. The real chip is rtl8188etv but the driver is the same. I have compiled 3.4.105+ Kernel to have the headers: mkdir ...