The kernel of operating systems popularly known as Linux, or sometimes GNU/Linux.

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Are there sandboxing concepts for proprietary binary kernel modules in linux?

Quite a lot has been going on to advance inter-process security (UID the same) and priveledge dropping in userland, yet it is common that proprietary linux kernel components are used (it seems that ...
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1answer
99 views

Is it possible to get the information for a device tree using /sys of a running kernel?

Commonly for arm systems, device trees supply hardware information to the kernel (Linux). These device trees exist as dts (device tree source) files that are compiled and loaded to the kernel. Problem ...
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111 views

Unable to boot after kernel upgrade

My PC triple boot Windows 10, Ubuntu 15.10 and Kali 2016.1. It boots from Ubuntu Grub. Everything worked fine until yesterday. Yesterday Kali released version 4.4 of the kernel and I installed it. ...
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2answers
110 views

Why does it take so long to detect an usb stick?

I'm writing an initramfs-script and want to detect usb-sticks as fast as possible. When I insert an usb 2.0 stick, the detection of idVendor, idProduct and USB class happens within 100 ms. But the ...
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0answers
61 views

Extremely high shmem usage

I'm trying to debug the issue that's periodically taking down my work machine. It's an OOM-type problem, and based on this /proc/meminfo output: Total: 32902608 kB MemFree: 4054100 kB ...
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5answers
416 views

Build Linux kernel to boot to Terminal

I am just getting started in Kernel hacking and want to build a kernel that will not launch an OS GUI but instead just go to a terminal command prompt. This is an attempt to debug an issue I'm having. ...
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0answers
70 views

CentOS 7 unable to cleanly umount a bind mount using rbind and rslave

The following sequence of commands will fail on CentOS 7 (kernel version: 3.10.0-327.10.1.el7.x86_64): [hidden]$ mkdir -p A B/a C/b [hidden]$ sudo mount --bind A B/a [hidden]$ sudo mount --rbind B ...
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1answer
61 views

why process running in kernel mode cannot be preempted [duplicate]

I read that user mode process are preemptive but why not kernel mode process?
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1answer
25 views

Is the kernel module made before or after a new system call? [closed]

I'm trying to incorporate a new system call in the kernel source. However, on checking some resources over the web, I cam across this term called "kernel module". I am confused how to go about it : ...
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1answer
85 views

Raspberry Pi 2 Custom Kernel with initramfs

I'm desperately trying to get a self-compiled kernel running together with an initramfs. It worked on the old raspberry, but somehow I can't get it to run. What I'm trying to do exactly: Load kernel, ...
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1answer
52 views

Unmount a rbind mount without affecting the original mount

Asked on serverfault but didn't get enough attention, so reposted here, with the hope some people here know the answer. There is another question discussing about umounting rbind mounts, but the ...
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1answer
211 views

How to resolve 'netlink: 12 bytes leftover after parsing attributes.' in syslog on Red Hat Enterprise Linux 6.5?

When I install customized RHEL 6.5 with no GUI, on the Virtualized Platform like Esx Server. I am constantly getting, kernel message netlink: 12 bytes leftover after parsing attributes.. And this ...
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1answer
39 views

/boot symlinks do not match current kernel version

I'm a bit puzzled on the following: I have a multi-kernel system, with a default one set by grub.conf, which is the 3.6 ; what I don't understand is why when I list the files in /boot/ I see the ...
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1answer
35 views

How do I find out how my currently Linux kernel was configured [duplicate]

I'm getting no core dumps, and core(5) says the problem might be that my kernel might be configured with CONFIG_COREDUMP, how do I find out if it is true? I'm on Mint 17.3 (uname -a: Linux laptop ...
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1answer
131 views

Installing linux kernel 4.4.0-trunk-amd64 crashes X server

I have installed Debian 8 and xfce. My machine is Lenovo Ideapad 500S. There's no information for this machine on how to properly use Debian on it. When I install linux-image-4.4.0-trunk-amd64 and ...
2
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1answer
26 views

How do I check if a specific fix in the Linux kernel has been included in a longterm kernel?

I'm specifically wondering if the patch for this bug has been included in the 4.1 longterm tree, or if it hasn't I'd like to know how best to keep tabs on when/if it does get included. The relevant ...
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0answers
57 views

FIPS mode, signature verification failed

I am building a kernel with FIPS mode on. I followed most of the procedures described on Red Hat documentation here. I also created a hmac signed .vmlinuz file. After installing dracut-fips and ...
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0answers
109 views

Please explain “kobject” [closed]

Hey I'm new into Linux and just started reading Linux Kernel Architecture by Wolfgang Maurer. Right in the beginning of the book he makes a note and tries to explain what kobjects are and their ...
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1answer
36 views

How to dump the dmesg AKA Kernel logs to a single .txt file from the kernel boot?

I am trying to understand the SATA Host-Device Communication and for that I have put a lot of debug messages in the kernel driver code. Now messages are in such a huge amount that I am not able to see ...
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1answer
103 views

Linux file system corruption due to improper shutdown (fs ext4)?

I have been managing many Linux servers, It is very easy to play with Linux servers than any other OS. But Sometime I encounter a problem with Linux OS is that, The file system corruption. This ...
3
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3answers
49 views

kernel configs and dependencies

When a particular kernel config is turned on, e.g. CONFIG_CRYPTO_FIPS=y a bunch of other dependencies (CONFIG_XXX_YYYY) get turned on during compilation. Is there a way to know all the dependencies ...
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0answers
24 views

embedded linux- to check uart in raspberry pi

Checking whether the Pi is sending and receiving UART data by installing the tool Minicom. Pi is sending serial data but is not receiving data. Whatever I type in Pi minicom is received to PC ...
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0answers
29 views

Why I can not update Linux core in dockers?

When I run apt-get update && apt-get upgrade in container, the core is not starting to update. Yes, I know, containers use the kernel of host machine and can not execute some ...
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1answer
40 views

Help in building Yocto(open embedded) projects using cluster computing in Linux

I need to reduce project build time in Yocto (open embedded) in Linux platform. So I decided to cluster computers for the best performance for compilation and building. My question: Is there any MPI ...
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0answers
21 views

How connected are kernel modules to kernel version?

I'm wondering how custom ROMs port new versions of Android (particularly the Linux kernel) to old phones. As I understand, Linux allows closed source kernel modules. If so, then when the phone ...
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1answer
132 views

Linux kernel, missing '__fentry__' symbol

Trying to build the EtherCAT master driver (realtime I/O driver) on a RT Linux (SL6.3) I keep bumping into a missing symbol issue when building the EtherCAT kernel modules: # make modules make -C ...
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104 views

Attach UVC camera to non-V4l2 Android device without rooting

The main issue is arising when I am trying to connect UVC compliant camera having CMOS sensor OV6612, to an Android device having kernel 3.0.x and OS 4.0.x, not having v4l2 driver. And no streamed ...
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2answers
167 views

Troubleshooting new linux system keeps freezing

I just built a new computer and installed centos7 (RHEL based) and I also tried mint 17.3 (Ubuntu based). Installation goes without any problems. The operating system runs smooth and everything is ...
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0answers
30 views

Where in Ubuntu SPI pins are configured?

I'm running Ubuntu on a custom embedded system. The SPI bus master is spi-pxa2xx. I've tried my code on several other systems and it worked fine. But on this system all I see is CS activity while I'm ...
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3answers
543 views

What prevents distributions from using the latest Linux kernel? [closed]

Most Linux distributions ship with a certain kernel version and only update it on point releases (x.y.z to x.y.(z+1)) and for security updates. On the other hand, I know that Linux has a very strict ...
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0answers
11 views

Remotely use a platform device

I have a linux/android device with a certain hardware module (lets call this pc A), and a driver which uses the hardware as a platform device. Because of testing/os restrictions I'd like to be able ...
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2answers
151 views

Is there any way to hide kernel threads from ps command results?

When I type ps -ef , there are lots of special kernel thread processes showing. I am not interested in kernel threads; I am only interested in user process/thread. Is there a way that I can hide the ...
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How much control do concrete file systems have over the VFS inode cache and the buffer cache?

I want to make sure I'm understanding how VFS inodes and file system inodes working together. A file system's inodes are stored on the block device and that is where they live. When an operation is ...
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0answers
45 views

Booting into linux kernel 4.1.3 using qemu

I am trying to boot into a compiled Linux 4.1.3 bzImage (disabled modules, so I only had to make bzImage). Correspondingly, I installed ubuntu 15.10 (with Upstart, not systemd) on a qemu cow2 image ...
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3answers
87 views

how to monitor a unix directory and if any new file in directory it will be copied to another directory

I want to monitor a unix(Solaris 10) directory and if there is any new file i want to copy immediately. Tried: I have shown inotifywait and incron package in linux for it but i don't know whether it ...
3
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1answer
54 views

Does the O_DIRECT flag bypass the Linux page cache when accessing block devices too?

I am running a lot of KVM virtual machines, which open the hard disk image with the O_DIRECT flag. I understand, according to the open() man page, that using O_DIRECT will try to bypass the Linux ...
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0answers
36 views

Dereferencing string pointer in ftrace event filter

I'm currently trying to create an ftrace event filter for the event sys_enter_open which is filtering by the filename argument. Looking at the format definition of it I can see there's a filename ...
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1answer
50 views

make + bash: setting environment variables on command line doesn't work

I am trying to build the kernel for Raspberry-pi on my Debian-8 host machine. I passed the following commands to build the kernel make ARCH=arm KERNEL=kernel CROSS_COMPILE=arm-liux-gnueabihf- ...
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1answer
120 views

Linux not using all memory

I have a PC with Fedora 23 OS with 4 GB RAM, but usable memory is 2 GB. When I tried to check memory: # dmesg | grep Memory [ 0.000000] Memory: 1753008K/1816676K available (7670K kernel code, ...
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2answers
60 views

Booting stops at Loading initial ramdisk

I have installed Arch Linux on 40GB HDD on ga-g4mt-s2p1 Motherboard ( Intel Core 2 multi-core,2Gb of Ram) I have made 4 Partitions: /boot 100Mib Swap 4Gib / 20Gib /home The rest of the disk It ...
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0answers
14 views

init & System V IPC in kernel

Does it affect init if System V IPC is not compiled into a kernel? Does init require System V IPC?
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32 views

Add a module to linux kernel source code statically [closed]

I am new to linux kernel programming. I have explored that there are two ways of adding modules to linux. One way is by dynamically linking the modules with the running kernel using insmod and another ...
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0answers
22 views

Why are there no LSM hooks in the POSIX IPC APIs?

As I understand it, the Linux Security Module (LSM) framework has many hooks which are callbacks for security modules to register functions performing additional security checks before ...
3
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1answer
58 views

Can the kernel symbols' addresses be influenced? consequences?

tl;dr: in my distros linux 3.08 kernel using cat /proc/kallsyms I can find out that for instance the _commit_creds function/symbol is located at address 0xc1073fe0. When either: building my kernel ...
4
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1answer
126 views

how to eject/unmount usb dongle logically?

We've bought a commercial application who just work only if their dongle usb is connected to the server. However sometimes the application can not recognize the dongle, so it doesn't work, but if ...
2
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1answer
56 views

Why does Linux have a maximum number of sound cards? [closed]

I'm specifically asking about CONFIG_SND_MAX_CARDS in the kernel. From the code using this config, for example in sound/usb/card.c for USB cards, soundcards are stored in plain arrays which are ...
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0answers
50 views

Linux kernel running only with use of physical address

Is it theoretically possible to make Linux which for its own kernel (include modules) uses only physical addresses? (it means it completely omits MMU) For processes how would you know if there was ...
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0answers
18 views

Changing the Retransmisson Timeout (RTO) estimation in Fedora

Retransmission Timeout(RTO) in a TCP plays a vital role in the internet. There are many algorithms proposed for calculating the Retransmission timeout. RFC 6298 is used for the estimation of RTO. I ...
2
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1answer
262 views

256 colors in console (tty)

Suppose, I have a system without X server. I can only log in from the console. It seems, by default linux console supports only 8 colors: # tput colors 8 Is it possible to use 256 colors in the ...
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0answers
48 views

Need help determining why a usb device works in Ubuntu but not ChromeOS

I am troubleshooting a problem with an Epson Brightlight 536wi projector. When you plug a USB cable from the projector into a Windows or Linux computer there is a driver built-in to both Operating ...