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

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Wacom Tablet (integrated; X201T) disconnects sporadically

I have an X201 tablet with stylus and finger multitouch running Ubuntu 14.04.4 with the 4.2.0 kernel. For no apparent reason, it seems to have an affinity for not recognizing finger (henceforth ...
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60 views

How to know when I could reactivate HWP (Hardware PStates)

I have a x1 carbon 4gen, and my computer hangs during boot on "HWP enabled" message. For now the solution is to disable HWP (Hardware PStates) with the option intel_pstate=no_hwp on boot. There is a ...
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2answers
13k views

Partition table not recognized by Linux kernel

I experience relatively often that the partition table of a USB stick or SD card is suddenly no longer recognized by the kernel while (g)parted and fdisk still see it, as do other systems. I can even ...
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Kernel make install error for RTAI 3.8 on CentOS 6.5

Before posting I have read almost every similar post I could find on this and other websites but I haven't found an useful answer. I have to install a custom software that needs RTAI 3.8 on top of ...
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62 views

Kconfig (bool/def_bool/tristate)

In a Kconfig file, what are the differences between : bool def_bool tristate Thank you.
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2answers
95 views

How to get the absolute position (x, y coordinates) of a finger on a touchpad?

Main question: How to get the absolute finger position on the touchpad? I would like to get the absolute position (x, y coordinates) of a finger on a touchpad? I believe it is possible to extract it ...
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2answers
738 views

Wireless constantly reconnecting on Ideapad running Arch

I just bought a new laptop, a Lenovo IdeaPad U330 touch, and after some struggle (with the Secure Boot stupidity) I have managed to install Arch Linux. I have configured my system, installed all the ...
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30 views

is there a description for kernel messages?

I use dmesg to output kernel messages, but since I'm new to linux I have no idea what this informations mean. Is there a good tutorial or description so I can understand the messages. for example: ...
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23 views

Mouse button stops working intermittently

I have noticed that I'm not the only one with mouse button problems. This problem seems to affect multiple users on many different Linux versions regardless of Desktop versions (at least in Unity &...
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1answer
66 views

What step am I missing to get my 2.6 ARM kernel running in QEMU?

I am trying to cross-compile and boot a Linux 2.6 kernel for ARM using QEMU. I have basically followed the same instructions that are included in seemingly every single tutorial on the topic. ...
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How to trace the life cycle of kernel threads by following creation and switching?

How to trace the life cycle of kernel threads by following creation and switching ? kernel_thread() and schedule() are the 2 functions I know that but have no idea how to implement it..
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289 views

Why can't I find kernel headers on CentOS 7 when trying to install VirtualBox Guest Additions?

I have a minimal CentOS 7 installation as a VirtualBox 5.0.16 r105871 guest on a Windows 8.1 host. uname -r reports "3.10.0-327.10.1.el7.x86_64". When I try to run VBoxLinuxAdditions.run I get an ...
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Raspbian Kernel Oops at fs/dcache.c

We have a Raspberry Pi 2 running Raspbian 8 Jessie. We are running a simple Python 3 based Flask server to read from GPIO pins and toggle a relay (Externally powered). This system is polled every ...
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18 views

Ubuntu upgrades blocked due to insufficient disk space for linux-image [duplicate]

I am running Ubuntu Server 14.04 LTS on a desktop at my home that I was intending to turn into a server, but I never really did much on it. I then decided to turn it into a send-only SMPT server, but ...
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24 views

GMA500 video chip uses mode that monitor can't sync to (even text mode)

I have a new CentOS7 installation which starts fine (I see the Grub2 menu). If I disable RHGB I can even watch bootup to a point - then all video disappears. The OS is booting to runlevel 1 (text ...
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2answers
130 views

Why can't I run android apps on generic linux? [closed]

I know about projects like archon, and various emulators exist, but it seems strange that I can run windows programs but not android programs under a stock linux kernel.
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Dynamic mdev ifup and ifdown of network interface

Is it possible to have an mdev.conf rule that would run ifup on device creation and ifdown on detach? i.e. eth[0-9] root:root 660 @ifup $MDEV | $ifdown $MDEV
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1answer
189 views

How to install kernel 4.4 on debian testing?

Hello can someone tell me how to install kernel 4.4 on current debian testing ? I have a bug that might be solved by the kernel 4.4 so I want to give it a shot but can't find the name of the package ...
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1answer
672 views

How to troubleshoot high kernel time (high network usage; high interrupts)

I've noticed that I have high kernel time when doing a lot of network traffic in Linux. I also noticed that 45% of my CPU is spent doing interrupts. How can I further troubleshoot this?
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2answers
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How can I activate extra-verbose mode (debugging mode) during Debian boot?

How do I activate extra verbosity during boot, on Debian? I removed the quiet parameter and tried to add debug but it didn't help. My problem is that my keyboard takes 2-3 min to activate so it ...
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153 views

How to interpret perf -e cache-misses:pp?

I find the behavior of perf top -e cache-misses:pp -p <my_pid> quite confusing. I own an Intel i5-3230M, running kernel 4.4.5 64 bit. If I just run that commmand, I get basically no samples ...
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1answer
82 views

What is the difference between micro-kernel and monolithic-kernel? [duplicate]

I heard that Unix/Linux is a monolithic-kernel whereas Hurd is micro-kernel. So, I want to know what is the difference between these kernel type?
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Kernel panic dump analisys

We got a kernel panic today and I think that one scsi device caused it. Can you help me to interpret this output? What does <<EOE>> mean? <0>Kernel panic - not syncing: Watchdog ...
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How can I check my kernel preemption configuration?

I want to check if my Linux kernel is preemptive or non-preemptive. How can I check this using a command, something such as uname -a?
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Build custom EDID with several modelines

I would like to build custom EDID using kernel sources. But I need to use several modelines - more refresh rates for same resolution. Is it possible using method in kernel sources? Could you please ...
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96 views

How to install kernel sources

I 'm running Angstrom distribution (console only) on BeagleBoard-xM. Image was build on Narcissus, with Bootloader Files (x-load/u-boot/scripts) added. I noticed that usr/src directory is empty. I ...
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222 views

I installed linux. And it doesn't recognize usb keyboard and mouse

When I boot computer with kernel 2.6, I can use usb keyboard and mouse. But If I use kernel 3.10, It doesn't work. With kernel 2.6 $ lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root ...
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14k views

Where to download Linux Kernel source code of a specific version?

Is there a resource to download a specific kernel version source? For example, I want to get 2.6.36.2 sources to compare with this package and see what changes were introduced?
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1answer
36 views

How to map Linux hard drive identifiers like “sd 3:0:0:0:” to ones like “ata8:”? [duplicate]

In my kernel log, I can see entries like: [ 0.765510] sd 3:0:0:0: [sdb] 3907029168 512-byte logical blocks: (2.00 TB/1.81 TiB) and when something fails, it's usually something like: [ ...
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1answer
11 views

Add symbols of LKM to kernel

I am trying to get my android kernel working but I have a kernel module that is needed in order to get access to the file system of the device. Unfortunately there is no source code available so there ...
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2answers
158 views

How to make a minimal bootable linux (only with terminal) from kernel source code? [duplicate]

I want to make a very minimal linux os which only have a terminal interface and basic commands/applications (busybox is my choice for commands/apps). I don't want the installation option on my os. I ...
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CPU: 13 PID: 15452 Comm: ssd_blk/0 Tainted: G B I E 3.19.0+ #1

I developed a module which works as an emulator for a block device. When I write into the block device, I get this in dmesg and the module crashes. I cannot get any hint about what is going on? [...
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2answers
2k 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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2answers
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What 4.2 Kernel Optimizations could I make to speed up CR48 netbook?

I have a CR48, had one for years. Love the little grimlin, but it is still a single core machine with the chances of upgrading the processor being slim and none (Even then what looks to be the best ...
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33 views

Loop device support on self compiled kernel doesn't work

I compiled 3.10 kernel, I checked that these configuration lines are not commented CONFIG_BLK_DEV_LOOP=y CONFIG_BLK_DEV_LOOP_MIN_COUNT=8 When i'm trying to mount loop device I get this error # ...
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Error installing kernel from source!

I compiled the latest Linux Kernel (4.5.x) from Linus's git tree. The Kernel compiled perfectly with no errors. After compiling the kernel I installed the modules using sudo make modules_install. That ...
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1answer
67 views

How to spoof uname -rs per process

My ubuntu server returns Linux 3.13.0-63-generic when I run uname -rs. From what I found in internet, uname is also a system call which can't be easily overridden when third party program run this ...
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120 views

How to Downgrade CentOS 7.2 to 7.1 on Linode?

I can change Kernel on Linode Manager page, but I don't know how to Downgrade CentOS 7.2 to 7.1
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ip_local_port_range kernel parameter confusion

On my system we have following setting: [root@voip ~]# cat /proc/sys/net/ipv4/ip_local_port_range 32768 61000 We have asterisk running on it which is using RTP port range 12000-13000 in case we ...
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3answers
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Updating kernel but not packages

I need to update the kernel from version 2.6.30 to 2.6.37. I'm going to just compile the kernel and kernel modules for this architecture and boot it. But also there are a lot of packages installed, ...
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3answers
476 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.
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58 views

What part of TTY subsystem control the active /dev/ttyN (TTY device driver N)? [closed]

TTY subsystem contains TTY driver, line discipline and hardware drivers (keyboard driver, display driver). Let's say I use a virtual terminal/console. So, my current session uses /dev/tty1 (TTY driver ...
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25 views

bash's pseudo terminal master [duplicate]

I learn when we use pts, there is master of pts. Then, when we type the characters on the pts(which is the terminal of bash), not only the output of bash goes to pts but also its master? I confirm ...
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2answers
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how do I safely delete old kernel versions in CentOS 7?

I might be encountering odd symptoms resulting from competing kernels in CentOS 7. So how do I safely delete the old kernels? And how do I know which kernel is the newest one? Below is the ...
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895 views

Removing the rescue image from /boot on fedora

I am trying to upgrade my fedora system (21 → 22) using fedup. I removed all old kernels using package-cleanup but fedup still needs 2MB more on /boot. These are the files in /boot: -rw-r--r--. 1 ...
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1answer
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Cannot compile a linux kernel for an ARM board [closed]

I am trying to compile a linux kernel (2.6.32.70) for an ARM board (versatilepb), it is my first steps in embedded linux. At the end of the compilation, two compressed kernel images are generated ...
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4answers
1k views

What exactly happens when I execute a file in my shell?

So, I thought I had a good understanding of this, but just ran a test (in response to a conversation where I disagreed with someone) and found that my understanding is flawed... In as much detail as ...
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Help debugging a kernel oops

My system has been freezing up for a while, and I keep seeing this particular kernel oops: syslog. Xorg.log Here's another similar crash from a few months ago. syslog Can you help me debug this? How ...
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3answers
678 views

Cannot mount eCryptfs

I tried to install eCryptfs on my server to open an eCryptfs I did on my home computer. I got these errors. $ sudo mount -t ecryptfs /home/(place)/enc/ /home/(place)/enc/ Unable to get the ...