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

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How does GUI works different from the shell CLI?

For example if I want to remove a file I would write rm command in my shell CLI. But when I delete a file using GUI how does the process works ? For shell it would find the filesystem for rm program ...
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114 views

“rcu_preempt detected stalls on CPUs / tasks” message appears to continue

My board continues to display the message below. The terminal does not have any input. What is it with the following message, which I know? (T, g, c, q ...) What is the cause of this phenomenon? ...
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281 views

Linux Kernel - Wacom Tablet (CTL-490DW-S) - Lockout

I'm a bit of a beginner with Linux and after trying to fix this over the last few days I've finally given up and need your help. I'm trying to use my new Wacom (CTL-490DW-S (Intuos DRAW)) drawing ...
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47 views

Copy the Linux kernel config file to another distribution

I am installing new Linux distro (gentoo) and I want to copy the linux kernel config I have here in the linux mint live USB to the Gentoo system. The way Mint has the kernel config file is ...
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Problem with xv6 on qemu

I was doing the assignment on this link --> http://zoo.cs.yale.edu/classes/cs422/2013/lec/l2-hw After running make qemu the assignment document says A separate window should appear ...
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50 views

change size of devtmpfs /dev/

My new kernel has CONFIG_DEVTMPFS enabled, and thus my /dev is mounted as devtmpfs. My old kernel was not using CONFIG_DEVTMPFS, and /dev used to be mounted as plain tmpfs. Now I have noticed, the ...
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81 views

cannot read key “net.ipv6.conf.all.stable_secret” in sysctl?

I am running kernel version as followings on an Arch Linux computer: [root@router ~ ]$ uname -a Linux router 4.2.5-1-ARCH #1 SMP PREEMPT Tue Oct 27 08:13:28 CET 2015 and I noticed that every time ...
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95 views

No /dev/mmcblk0 during boot

I am trying to install CentOS-6 on an eMMC drive. Since the supported 2.6.xx kernel from CentOS-6 doesn't support mmc, I compiled a newer kernel (4.2.6) which has updated mmc drivers. I tried booting ...
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89 views

Different Debian versions from two different commands

This might be silly, but I'm new to Linux. I wanted to check my current Debian version so I typed uname -a and it gave me some stuff including Debian 3.2.73. But Then I found this command cat ...
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31 views

How to enable auto upgrade of kernel-devel package when kernel version is upgraded?

I have a USB wireless adapter for which I need to re-install a kernel module every time the kernel gets upgraded to a new version. But for installing this kernel module again, I need to download and ...
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Error while building Linux kernel for versatile board

I'm trying to build the 2.6.32.69 version of Linux Kernel for versatile board but I got this error during the build step init/mounts.o: In function `tty_port_users': ...
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How the terminal can run programs and show its output? [closed]

I'm slowly creating a mental model of how linux works, and I've tried to simplify the most, my model of how linux works. Let's assume that the kernel boots and inits the only software it's gonna run: ...
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My SLES 11 uses 6 GB RAM while nothing is running. How can I find out what is needing it? [closed]

Can anybody tell me what is consuming that much memory on my SLES 11 SP3 server? I suspect a serious bug in the kernel that it does not release memory allocated by an application once it quits. This ...
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24 views

vmlinuz damaged

Hello everyone I am new here. I recently purchased Ubuntu 14.04 LTS DVD from a retailer store. Then I burned the iso into my pendrive and configured the file isolinux.cfg. The file was alright. ...
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28 views

Change the parameters a kernel module loads with

When I plug in an SD card in Ubuntu, the module mmc_block loads with the value of mmcblk.perdev_minors set to 8. I am pretty sure this is the default value coded into the module. What file might I ...
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new kernel compile - error on bootup - Could not find overlay

I was compiling the kernel using slackware-current, the latest version of the kernel, 4.3.3, also tried 4.4-rc5, and ran into this error on bootup Could not find overlay #6 ### dt-test ### of ...
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1answer
43 views

Create serial console on plug in USB serial device

I have a CentOS 7 headless system with no serial ports. I sometimes want to access the server using a serial cable, so I plug in a USB serial cable (to my laptop's serial port) but I can't get a ...
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1answer
47 views

how do i know if the kernel changed

i have a scenario where i need to recompile my display drivers after kernel updates. i'm trying to shome how automate it with bash scripts during boot time. so i need some sort of a way to know that ...
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479 views

Xorg on skylake graphics hangs

I've bought msi gs40 that has intel i7 6700HQ which means integrated graphics hd 530. After a day of struggling I was able to start xorg with HD530. For this I addes i915 to initramfs and ...
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How can I upgrade my debian kernel to 4.3.2?

I am experiencing wireless stability issues and I'd like to upgrade my debian kernel So I'd like to know how can I upgrade my current kernel to the latest stable kernel on kernel.org ? (4.3.2)
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1answer
812 views

How can Linux 4.2.5 boot on a Skylake CPU when they are supported from 4.3+

I bought a Dell XPS 13 2016 with a i7-6500u (SkyLake). This notebook is not officially linux-supported but I found a few articles on how to get it up and running. But I cannot find an answer to this ...
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How can Wireshark see packets dropped by iptables?

I recently installed my hard drive in a new computer and after some fiddling around I noticed my iptables rules were dropping DNS responses for some reason, turns out they were configured to allow ...
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QT application doesn't receive udp broadcast since linux kernel 3.13.0-70

I'm developing a QT application on Ubuntu and suddenly had problems because QT app doesn't receive UDP broadcast messages. They are visible in Wireshark on that machine, but never received in QT. ...
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Bridging two interfaces with iproute2 doesn't work

I'm trying to create a bridge between eth0 and eth1 with iproute2, but there's always the error: RTNETLINK answers: Operation not supported when I use the command:ip link add name br0 type bridge. ...
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33 views

After my system crashed and I run crash, but I get the following error: not a supported file format

My system crashed and even though I haven't been able to know what caused the crash after going through the usual logs: messages, dmesg, secure, etc. There's nothing valuable I have seen on them so I ...
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ip link add gives me an error that it's not supported

I would like to set up a bridge with iproute2 like this: Adding bridge : ip link add name br0 type bridge Bringing bridge UP : ip link set dev br0 up Adding interface to bridge : ip link set dev eth1 ...
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45 views

Having a bad time installing Ubuntu

So, I recently upgraded my motherboard and processor. Windows was a real pain to me so I decided to go with Ubuntu. However, I ran into more than a few problems with my installation: When I tried ...
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34 views

DKMS modules never installed properly on kernel upgrade

I have multiple DKMS modules installed on my system, some of them mine, and some of them belonging to pretty major maintained packages such as Oracle's VirtualBox 5. What I've found is that on every ...
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28 views

Ubuntu DMA Auto Activate Optimization Flag

I have two NAS devices, which differ in architecture. They are connected to the same SATA disks and one of them shows better read and write performances. Okay, there could be many reasons for such ...
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69 views

Install Debian kernel header files 3.4.90+ via terminal for ARMHF

I am trying to install the kernel header files on Debian via the terminal, but it does not seem to exist in apt-get. The reason I need the kernel header files is because I need to install WiFi ...
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Assign virtual core number to specific real core

Is there any way to assign ''linux core numbers'' to specific real cores? I'm working with an asymmetric architecture, so not all cores are the same, and I want to assign specific cores number to ...
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99 views

building kernel cause dependency cycle error

I was trying to compile latest kernel with some edits. while doing sudo make modules_install INSTALL virt/lib/irqbypass.ko DEPMOD 4.4.0-rc1+ depmod: WARNING: found 2 modules in dependency ...
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What can interrupt execution of threads which are pinned to cores?

I do low-latency application development and I use isocpu and set thread affinity to reduce (eliminate?) context switching during my critical threads. However, I am unsure what other types of ...
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52 views

View current kernel parameters?

I saw in my syslog kernel.perf_event_max_sample_rate get changed. I was wondering if I could write a quick script to log this variable every few minutes. Currently it is: sysctl -a | grep ...
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38 views

Why are there module options AND driver options - e.g. for the i915 module?

The i915 Kernel module has several "module options" like the infamous enable_rc6. However, for the xorg config file, there are further options such as TearFree. I was wondering - why are there two ...
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Diagnosing regular crashes with data loss?

I'm on Kubuntu 15.04 on a HP zBook 14. Every few days, my computer locks up completely - screen stays on, sound get stuck and plays the last few tenths of a second of what ever was playing over and ...
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184 views

Installing Linux onto Teclast X80H x86 tablet

I'm trying to install Linux (any linux, but preferrably Ubuntu Mate) onto my cheap tablet Teclast X80H, which came preinstalled with WIN8/Android x86. Main specs are: CPU: Intel Bay Trail, 1830 MHz, ...
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70 views

Why cgroup cpu items are miss in Debian 8

the kernel version for debian 8 use 3.10. But under /sys/fs/cgroup/cpu, miss a lot of cpu items. vagrant@debian-jessie:/sys/fs/cgroup/cpu$ ls -1 . cgroup.clone_children cgroup.procs ...
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no bios, black screen on laptop after kernel upgrade and hibernation

I am running dual boot Windows 7 and Linux Mint 17.2 on an ASUS K56. I upgraded the kernel to 4.2 the other day. Reboot and everything worked just fine. Tested browser, music player etc. Then I leave ...
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sysfs alternative to /proc/acpi/button/lid/LID/state

As you probably know ACPI procfs is deprecated in new kernel versions and with sysfs I don't know of a clean way of reading the state of the lid button. The only way I've come up with is hooking up ...
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How do I configure a systemd service to execute simple /bin/echo “Hello world” command to show the output on the console?

I am trying to boot up a vm with qemu-system-ppc64(similar to lkvm). I am using the following command: qemu-system-ppc64 --enable-kvm -vga none -nographic -nodefaults -chardev stdio,id=id1 ...
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786 views

When will Debian switch to Linux 4.x?

Wikipedia says that current Debian 8.2 Jessie is based on kernel 3.16.0, so I was wondering when a native version based on kernel 4.x would be released and if the live kernel patching will be there as ...
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32 views

How to find hugepage size on system?

I am getting following two different result. which one i should consider for Hugepage? [root@server ~]# getconf PAGESIZE 4096 [root@server ~]# grep -i hugepagesize /proc/meminfo Hugepagesize: ...
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1answer
69 views

Appending files to initramfs image - reliable?

I'm modifying a bunch of initramfs archives from different Linux distros in which normally only one file is being changed. I would like to automate the process without switching to root user to ...
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Unable to view printk output

I have been trying to debug my kernel code with printk statements. But the messages does not show up on the console. cat /proc/sys/kernel/printk gives 7 4 1 7. What could be the reason?
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Why number of dirty pages is always 0 on 2.6?

In /usr/src/linux/Documentation/filesystems/proc.txt i've found the string: Table 1-3: Contents of the statm files (as of 2.6.8-rc3) ...
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Map non-standard hid reports to scancodes for Logitech G105 Gaming Keyboard

So, I've recently purchased the named keyboard and have been doing some reverse engineering as to how the Logitech Gaming Software does things with it. In this process I've discovered that a few magic ...
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32 views

Only booting to GRUB automatically

I installed Elementary OS earlier as the sole OS on my machine. When I boot now, GRUB is displayed on the screen (with a message about minimal bash being available). I can boot to Elementary OS by ...
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Automated kernel recompilation on security patches?

I'm on Ubuntu 14.04 and really enjoy the fact that I get automatic kernel security updates. When a kernel security problem is patched, a new package will be shipped with the new version. My machine is ...
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Microkernel (e.g. GNU Hurd) more secure than monolithic kernel (Linux)? [duplicate]

I would like to understand (in relatively layman's terms) if and how a microkernel such as the Mach-based GNU Hurd is more secure than a monolithic kernel such a Linux. Additionally, does a ...