Questions tagged [kernel]
Everything about UNIX kernels: development, configuration, compilation, design, etc.
2,287 questions
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How to additional public keys to .secondary_trusted_keys?
I am trying to add additional keys to .secondary_trusted_keys. Documentation says, to do so the additional keys has to be signed by a key which is already a resident in either .builtin_trusted_keys or ...
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0answers
31 views
How can you write to the kernel memory? [on hold]
During boot the kernel is loaded into memory and also in-memory filesystems like /proc or /sys are created.
How can you change values in those filesystems? Or how could you change the dmesg output, ...
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0answers
13 views
How does Linux actually perform protocol data unit (PDU) encapsulation?
I understand that as data goes from the upper layers (Application Layer) to the lower layers (Physical/Link Layer(s)), the data is encapsulated. When it goes back up the layers, it is decapsulated.
...
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0answers
20 views
RBP 3+ Stuck at rainbow screen after LUKS encryption
I'm trying to create a raspberry pi with kali linux that is encrypted with a key that is located on a USB device, so it doesn't boot without the USB device plugged in. I followed this guide: https://...
0
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1answer
48 views
Keyboard issue console terminal
I have an issue on my Debian computer with Intel Stick.
Link to screenshot =>
I have extra character in console tty like ^[
This issue is only with supperior 4.11.12 kernel
Debian kernel and 4.11....
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0answers
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Can I generate a single device tree dts file from all the files in my device kernel?
I need to fix a driver that is using a node in the device tree, the problem is that the node and it's aliases are all over the place, separated through few different files with few overrides and it is ...
0
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1answer
58 views
how to acheive: minimum kernel processes and minimum userland processes?
Basically, I want to have an embedded-linux to run a single application, but with minimum kernel process and minimum userland process:
I don't really care the size of kernel or root file system. (...
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7 views
Communicating between userland and kernel space (KEXT) on MacOS
In order to make it easier to develop a kernel module, I am considering Loadable kernel modules (LKMs) on MacOS. This way you have a base kernel module and your main kernel module which is an LKM ...
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1answer
19 views
How to log every instruction and change in memory in any process
I read here this:
Falco depends on a kernel module that taps into the stream of system calls on a machine and passes those system calls to user space.
(Emphasis mine).
That hints at the ...
-1
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0answers
17 views
The things that can run in kernel-land [closed]
I learned that you can write device drivers that run in kernel land, and am now wondering what other sorts of (major/important) things you can do at the kernel level that you can't do at the user-...
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0answers
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How to get notified of a USB plugin and manually specify the driver to use
I am trying to get at the bottom of how to intercept when a USB is plugged in, so that you can completely customize the experience of plugging it in and using it. Without anything else happening. That ...
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0answers
16 views
add intel driver module to initram for pxeboot
I'm triying to boot system-rescue-cd via pxe.
The Problem on the actual system is, the driver for the network card (intel 82574L) e1000e is not in the initram.igz file, so the system can boot the ...
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1answer
41 views
How to disable retpoline?
I need to disable retpoline for a use case. I tried adding noretpoline to the boot parameter but it doesn't seem to work.
The output after adding noretpoline param:
$ cat /sys/devices/system/cpu/...
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0answers
56 views
+100
How to verify a kernel module signature?
When you compile a kernel source, you can choose to sign kernel modules using the CONFIG_MODULE_SIG* options. The modinfo tool should handle the task of verifying the module signature, but there has ...
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0answers
19 views
data race within ptr_ring code implementation
I am implementing single-producer,single-consumer ptr_ring buffers. Are there really data races within this linux driver code ?
I asked this because ThreadSanitizer gives me error and my system ...
3
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2answers
80 views
How can I avoid my boot and kernel partitions getting out of sync?
I apparently screwed up my Arch Linux system by inadvertently updating the kernel, but not the boot partition. So, for example:
pacman -Q linux -> results in 4.20.arch1-1
uname -a -> results ...
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2answers
38 views
Rootfs versus kernel confusion [closed]
I know that they are two different entities. Rootfs is a file system which describes how to store and access data. The kernel is actual code which executes.
However, isn't the kernel code stored ...
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1answer
27 views
A procedure of caching data in linux kernel, especially on LLC
I wonder how kernel puts data on LLC or L3 caches in detail. I have been searching the information about using cache in kernel but many results talk about page cache or buffered cache but in this ...
2
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1answer
21 views
Access grab state of evdev device
I need to retrieved the grab state of an evdev device in a program. More specifically, I need to retrieve the state of the grab pointer in the evdev struct seen here: https://elixir.bootlin.com/linux/...
0
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1answer
92 views
Compiled kernel 4.19 will not boot: “Kernel panic not syncing : System is deadlocked on memory”
I am compiling kernel 4.19 on Ubuntu 14.04 because I have a assignment to add a system call, but when I try to boot this kernel there's a error:
Kernel panic - not syncing: System is deadlocked on ...
1
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1answer
22 views
Have to rmmod and modprobe every time I start up
I have got a raspberry pi and I've installed it correctly the 8821cu module for my Wi-Fi Dongle and it works ok.
But every time I reboot the pi I have to sudo rmmod 8821cu && modprobe 8821cu ...
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36 views
Unable to read SD cards linux
I'm unable to read any SD card from Linux. I already tried both SD cards that I have here in different machines (windows and Linux) and they work flawlessly, I also booted from a live USB (the same ...
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0answers
20 views
Reduce used display size for both X server and console
I have the situation that I have a LCD display that I would like to use but I want to have a "black unused frame" around the displayed content. Is there a kernel setting which controls the used ...
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0answers
37 views
“make xconfig” raises a Qt error
When I call make xconfig in my linux kernel source directory, I get the following error
scripts/kconfig/qconf Kconfig
Gtk-Message: Failed to load module "canberra-gtk-module"
Qt: Session management ...
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0answers
28 views
Can not Mount “/dev/hdb on /cdrom” on Carrier i-Vu CCN
I had to replace a hard drive in a Carrier I-VU HVAC Control server for a nursing home with no heat. I am not a HVAC guy but am trying to get heat back on because repairman could not get it for a week....
3
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0answers
95 views
How differently from Linux kernel does a typical Unix kernel (System V, Free BSD, …) implement processes and threads?
In my previous post, about the Linux kernel,
the structure task_struct represents threads i.e. light weight processes, but not processes.
processes are not represented by any structure, but by ...
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0answers
37 views
compile and use a realtime kernel on CentOS 7
I would like to compile and use a realtime kernel on CentOS 7. I found a guide on the web:
http://jensd.be/589/linux/complile-and-use-a-realtime-kernel-on-centos-7-or-rhel-7
When I try to use it I ...
2
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0answers
68 views
Are .text sections shared between loaded ELF executables?
If one program, for example grep, is curretly running, and a user executes another instance, do the two instances share the read-only .text sections between them to save memory? Would the sharing of ...
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2answers
33 views
kdump in CentOS 7
I wanted to migrate to CentOS 7.5 from CentOS 6.9. during installation I saw an option kdump that i could enable or disable. I wonder what is kdump and disabling it has any bad effect on server? I ...
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0answers
70 views
FIPS integrity test failed on RHEL 7.5 with 4.X kernel
I have a Dell PowerEdge R7425 with Intel NVME P4500/P4510 NVME drives.
On the 3.10 kernel, the NVME drives throw I/O errors very frequently, and these errors have led to a system halt once already.
...
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0answers
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About `page_table_lock` in Linux process address space
I'm reading a tutorial about Linux page table, in the linked page
Each process has its own page tables (threads share them). The pgd field of the memory descriptor points to the process's page ...
6
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1answer
177 views
Kali Linux kernel headers for 4.14.71-v6
I am trying to install kernel headers version 4.14.71-v6 (uname -r) for Kali Linux. I already did the common commands...
apt update
apt upgrade
apt dist-upgrade
apt install linux-headers-generic
alt ...
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0answers
34 views
Kernel panics only with ACPI enabled
I have ubuntu 16.04 on my laptop. It was working good until few days ago.
The system won't boot. It logs ACPI errors and then kernel panics:
ACPI Error: No handler for Region [RAM_] ( (ptrval)...
0
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1answer
29 views
Do rolling release distros like Arch Linux include kernel upgrades as part of their rolling upgrades?
Do fully rolling_release distros like ArchLinux, openSUSE, Alpine and so forth include kernel-upgrades as part of their rolling upgrades?
Or kernel upgrades are a separate issue even within the ...
0
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1answer
84 views
How to Install or Upgrade to Kernel 4.19 in CentOS 6
# lsb_release -a
LSB Version: :base-4.0-amd64:base-4.0-noarch:core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch
Distributor ID: CentOS
...
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2answers
63 views
Why /proc/meminfo shows MemAvailable under Kernel Version 3.10?
I've been using CentOS 7 and its kernel version is 3.10. To check Kernel Version, I typed 'uname -r' and command showed 3.10.0-957.1.3.el7.x86_64
As far as I know, MemAvailable metric was introduced ...
1
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1answer
20 views
Resource locking in interrupts
I have a kernel module with netfilter hooks at different points in the packet route, and the hooks use shared resources. In addition, the module has a char device that may be written to, that also ...
2
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0answers
19 views
What happens to memory that wasn't freed in a kernel module after unloading?
Suppose I called kmalloc and didn't free that memory before rmmod was called on the module, what happens to that memory? Is it a memory leak and it is completely unusable until restart, or does the ...
0
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1answer
26 views
mismatch between kernel version and kernel header
I use an embedded with a bit old kernel 2.6.37.
Now we need to update rootfs with more update gcc than the one used on building the image (Instead of 4.3 need to use 5.1, because it will support c++11,...
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0answers
26 views
GUI won't boot after package update: Restoring Resolver State [closed]
Linux Mint Rosa dual boot with windows 10
Nvidia GTX 870M
Suddenly can't get to Linux Mint gui after running a package update to upgrade python. Everytime I login it kicks me back out. flashing this ...
1
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2answers
42 views
Can kernel upgrades be done with configuration management (CM) tools for above-OS software?
I use various Linux Distros, mostly Debian-based, usually all default (I change nothing in the kernel/shell or internal-utilities (utilities that come with the distro). I usually install Apache, MySQL ...
0
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1answer
31 views
Linux kernel module development buildroot
I have build a linux kernel for the beaglebone black using buildroot. Now I would like to develop a hello world linux kernel module application:
#include <linux/init.h>
#include <linux/...
1
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1answer
61 views
When the operating system shuts down, how does a service manager know that it should sends SIGTERM and SIGKILL to its services?
Reading one of Stephen's excellent replies,
When the operating system shuts down, processes are shut down using SIGTERM and SIGKILL, but those signals don’t come from the kernel (or not directly — ...
2
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2answers
694 views
What is the difference between “when the operating system shuts down” and “when the kernel shuts down”?
Reading one of Stephen's excellent replies, I was wondering what differences are between
When the operating system shuts down. ...
and
When the kernel shuts down, ... (... I’m considering that ...
1
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1answer
26 views
What are the benefits of using longer/shorter periods in cpu.cfs_period_us?
When you want to limit CPU time per process, you can do it via cgroups. There are two parameters that can do the job: cpu.cfs_period_us and cpu.cfs_quota_us.
There's some info on the parameters here:
...
1
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1answer
58 views
Elan touchpad: Kernel Config
I'm running Gentoo Linux on an Acer Chromebook 15 (CB5-571 auron_yuna) and I have a minimal kernel configured supporting everything I need except for my Elantech touchpad. I've read a bunch if other ...
1
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1answer
62 views
Lenovo Thinkpad Mute LED Stopped working after update
Updated my packages today on my Lenovo Thinkpad X1 Carbon (6th Gen). I didn't expect anything to happen but it did. The Mute indicator LED's on the F1 and F4 key stopped working.
I actually know this ...
0
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0answers
21 views
Lifespan of blocks in a UNIX block-cache
Recently, I've been getting into OS development and have been experimenting with writing my own small kernel. I've just begun to look understand and implement a block-cache, for caching data read from/...
8
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4answers
823 views
Why does the kernel even bother to send SIGKILL? [duplicate]
If a program is not allowed to handle or ignore SIGKILL and SIGSTOP, and must immediately terminate, why does the kernel even send the signal to the program? Can't the kernel simply evict the program ...
3
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1answer
41 views
Why are du -h / du / df / df -h not refreshing when extracting a large file
I am running tar in the background, eg:
tar xfvz large_file.tar.gz &
It does extract my file, but when I then launch du -h, du, df or df -h, the output remains the same, and I have to wait ...
