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
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Recognizing GPT partition table created with different logical sector size

I have a 3TB drive which I have partitioned using GPT: $ sudo sgdisk -p /dev/sdg Disk /dev/sdg: 5860533168 sectors, 2.7 TiB Logical sector size: 512 bytes Disk identifier (GUID): ...
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20 views

Centos 7 not starting anymore [on hold]

My Centos 7 VPS is just crashed and not starting anymore. I get several errors when starting and is not responding anymore. Errors (random on rebooting) Unable to handle kernel paging request ...
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1answer
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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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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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What does kernel refer to load modules at boot time? [on hold]

lsmod is command to list loaded modules and I referred man page of lsmod that shows it refers to /proc/modules file. In terms of my os platform, Ubuntu, almost available modules are in /lib/module ...
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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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35 views

Debian wheezy, 3.19, problem keyboard and mouse on dekstop environment

I am running Debian Wheezy on a BananaPi. I just compiled the kernel and the keyboard was working in terminal(if it's called that way). However, after I installed a dekstop interface using "apt-get ...
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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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Strange return type of __get_free_pages [migrated]

Why does it return unsigned long? Why not void* or char*? unsigned long __get_free_pages(unsigned int gfp_mask, unsigned int order) I guess it returns an adress, or have I misunderstood that ...
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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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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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Centos 7 boot up with custom kernel problem

I have installed centos 7 on virtualbox machine which has kernel-3.10.0-123.20.1.el7.x86_64. I am trying to build Linux kernel from kernel sources. I downloaded the kernel source files from: ...
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40 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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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
38 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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1answer
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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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setting (system-wide) CPU affinities for running processes on a Linux platform

I am conducting a kind of research in that I schedule multiple parallel applications (e.g., OpenMP/pthreaded applications) and execute the applications on specific (partitioned) cores on Linux-based ...
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Why is does proc_create mode argument 0 correspond to 0444 [migrated]

I am a newbie to kernel programming and am trying to userstand procfs. I have googled several examples and they all use: proc_create("hello",0,NULL,&proc_fops); where the second argument is the ...
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1answer
27 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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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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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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Compiling kernel, MODPOST 0 modules

Building modules, stage 2. MODPOST 0 modules I am trying to compile a linux-sunxi kernel for my Banana pi. Using this link: http://sunxi.org/Linux_Kernel#Compilation Unfortanately I am getting ...
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63 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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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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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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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
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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
45 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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21 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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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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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 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
73 views

How to disable core dump generation in Centos (cPanel Server)?

I want to disable core dump generation, How can I disable it ? One of the website keeps generating core dumps every second and eats up all the disk space. OS Details: CentOs cPanel Server ...
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1answer
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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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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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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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1answer
25 views

How to see kernel time variables without using adjtimex?

The man page for adjtimex says Anyone may print out the time variables, but only the superuser may change them. How do I see the value shown by adjtimex -p as the tick variable without using ...
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61 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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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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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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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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2answers
105 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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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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3answers
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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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220 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 ...
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0answers
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View syscalls/kernel activity for I/O from a running process

I'd like to be able to view syscalls or kernel activity for a process...I'm not actually sure of the terminology I need here! Specifically I'm looking for the difference between I/O going to local ...
2
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1answer
39 views

What is /proc/filesystems supposed to be and why is it different from /lib/modules/linux_ver/kernel/fs?

The very little documentation about /proc/filesystems says it is a "list of supported file systems". I see a lot of file system modules in /lib/modules/linux_ver/kernel/fs, most of which do not appear ...