Questions tagged [linux-kernel]
This tag is for questions about the internals of the Linux kernel itself - particularly about use or configuration of kernel modules or drivers.
491
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How to sign a kernel module Ubuntu 18.04
I am new to using Ubuntu. I am trying to install Genymotion so I can have access to an android emulator. In order to use Genymotion, it is required I have VirtualBox. I have VirtualBox installed but ...
- 641
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votes
5
answers
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How to get a list of active drivers that are statically built into the linux kernel?
While I can use lsmod in order to show currently active kernel modules, how can I see which drivers are statically built into the kernel AND currently active?
- 4,968
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votes
5
answers
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Is it possible to make the OOM killer intervent earlier?
I try to tweak my development system to maximal reliability. I disabled swap, because for GUI usage it mostly renders the machine unresponsive in such a way not useable anymore. Nevertheless, if ...
- 1,908
40
votes
2
answers
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39
votes
7
answers
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Unable to install VIrtualbox, `"Specify KERN_DIR=<directory>"` -- installing Virtual Box to Debian?
I am getting this error:
Makefile:181: *** Error: unable to find the sources of your current Linux kernel. Specify KERN_DIR= and run Make again. Stop.
Basically I'm doing:
$ sudo /etc/init.d/...
- 683
35
votes
7
answers
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VirtualBox Ubuntu Guest Additions not installing : modprobe vboxsf failed
I just installed this software off virtual box, i downloaded the ISO off the official ubuntu website, was the lastest LTS.
I attempted to install Guest Additions using the 'Insert Guest Additions CD ...
- 451
34
votes
3
answers
4k
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Why does the Linux SCSI subsystem drive hardware not obviously related to SCSI?
Without knowledge, I would normally expect SATA, SCSI and USB Mass Storage to be driven by different drivers. In Linux however, the SCSI subsystem drives all of them.
Why does Linux use the SCSI ...
- 523
34
votes
5
answers
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What does "sudo -s" actually do?
I am using ubuntu 10.04.
I notice that after I run in terminal:
sudo -s
The prompt changed from:
my_user@my_hostname
to:
root@my_hostname
Seems it changed to root privilege.
But when I check the ...
- 513
32
votes
1
answer
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Enable user namespaces in Debian kernel
I'm trying to figure out how to enable user namespaces capability in my kernel (I think CAP_SYS_USER_NS). I'm using Debian Stretch, kernel 4.6.0-1-amd64.
My assumption is there is a way to turn on ...
- 321
29
votes
1
answer
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Where can I find the Linux kernel file?
Is there any common directory to find kernel file in all Linux distributions?if yes please tell me how to browse to the directory?
Where can I find the Linux file in Ubuntu & RedHat operating ...
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23
votes
7
answers
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How do I uncompress vmlinuz to vmlinux?
I have already tried uncompress, gzip, and all other solutions that come up as google results and these have not worked for me.
To get just the image search for the GZ signature - 1f 8b 08 00.
>...
- 1,014
22
votes
2
answers
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How to check which SysRq functions are enabled?
The file /proc/sys/kernel/sysrq contains a single number, such as:
1 (enable all SysRq commands),
0 (disable all),
or a base-10 positive integer which functions as a binary bitmask, enabling a subset ...
- 3,704
21
votes
4
answers
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How to view all boot messages in Linux after booting?
Relevant questions are:
Where Linux places the messages of boot?
Name of log file where boot process is logged
However, these do not answer this question. This question is concerned with how all ...
17
votes
2
answers
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What is the exact difference between the parameters (pgpgin, pswpin) and (pswpout, pgpgout) in /proc/vmstat?
Please note that this question is specific to linux only. And by swap space, I mean the dedicated swap partition.
I did google a bit on this, and found these definitions:
Paging refers to writing ...
- 585
13
votes
4
answers
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Linux kernel hangs at 'Switching to clocksource tsc" on Pentium 4
Hardware: Dell Dimension 4500S : i845G, Pentium 4, stock + 2GB RAM and latest (circa 2002) BIOS update.
I've been building a Linux system from source, so far it's LFS 7.0 by the book. The first ...
- 272
12
votes
1
answer
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Linux overcommit memory
I've been looking into memory overcommitting in Linux using /proc/sys/vm/overcommit_memory, and I've read a few articles which don't say the same thing.
This doc, under the heading "Going in the ...
- 1,018
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votes
1
answer
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How can I prevent the kernel from limiting TX power as advertised by AP
I am connecting to eduroam over a distance of about 150m using an external 23dBm Antenna and an Ubiquiti SR71-E with an Atheros AR9285 chip. My system is Debian Jessie server - so the connection is ...
- 121
11
votes
5
answers
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Does linux have any measures to protect against fork bombs?
#include <unistd.h>
int main(int argc, char* argv[]) {
while(1)
{
fork();
}
}
I run this program on my linux, nothing outputs on the terminal, the OS seems go dead. Does linux have ...
venus.w
11
votes
1
answer
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How can I get the number of threads running in a process from /proc/[pid]/stat in Linux?
I have the pid of the process. I would like to know the current number of thread running in the process. I know I can read /proc/pid/stat for this information, but I'm not sure how to specifically get ...
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votes
4
answers
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How to search by content on Ubuntu
I'd like to search the entire server by content. (text file)
When I try grep -rl "text here", it freezes.
How would you do it?
And how long does it usually take?
- 225
10
votes
5
answers
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How do I fix Manjaro error hibernation device not found on boot?
After installing updates and restarting I got these errors.
ERROR: resume: hibernation device 'UUID=long number here' not found
ERROR: device '/dev/mapper/ManjaroVG-ManjaroRoot' not found. Skipping ...
- 213
10
votes
2
answers
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how to totally clear the filesytem's cache on linux?
In a performance test, I want to bypass the influence of cache of linux system (including page cache/inode cache and so on).
I have tried O_DIRECT flag, but it's turned out that direct I/O is still "...
tom_cat
10
votes
5
answers
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How do I stop rfkill module from hardblocking my wifi, without rfkill command?
I went into my BIOS the other day, didn't change anything, and rebooted. After this, my wifi was hardblocked. I looked online for solutions, and learned of the rfkill command. But I get
rfkill: ...
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9
votes
1
answer
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What is "modloop" option in Alpine?
I'm trying to understand what is the difference of making Alpine installation medium as read-only type (LiveCD) and as a standard disk mode (where the OS state can be saved). I've seen the modloop ...
8
votes
2
answers
19k
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Linux: Disable loopback interface from kernel
I know it is possible to bring down lo interface by doing ifconfig lo down. But is it possible to configure the kernel that the lo interface will simply not be available? Please note that I don't want ...
- 2,282
8
votes
3
answers
14k
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Not enough host controller resources for new device state
I have a debian mint based system where I plug in 16 usb devices.
The Kernal is: 3.11.0-12-generic
After about 10 or so devices I start to experience problems with connecting new ones.
There error ...
- 183
8
votes
2
answers
2k
views
Compiling the Linux kernel
Just for the learning experience, I have recompiled the Linux kernel with different options, installed and booted from it. It was both instructive and straightforward. However, I was overwhelmed by ...
- 191
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votes
1
answer
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Hairpinning in Linux
I have a router in which I installed a Linux system.
I want my router to support NAT hairpinning.
Does a such feature exists in Kernel Linux? If yes how to activate it? Are there a patch to apply it ...
- 359
7
votes
1
answer
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IPsec in the Linux Kernel
I have some issues (questions) related tot the Linux Kernel implementation of IPsec and it's user-space interface.
The biggest question is which is the actual official project for the Linux Kernel ...
- 259
7
votes
1
answer
10k
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Why is INSTALL_MOD_STRIP not on by default?
I haven't compiled Linux kernels in a couple of years, and now that I started doing so again I discovered that modules are installed with debug symbols by default unless INSTALL_MOD_STRIP=1 is passed ...
- 1,213
6
votes
6
answers
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Where can I find linux-kernel-headers-x.x.x.x for SUSE?
I'm installing VMware Workstation on a SLED 11 SP1, and the installation is blocked by an error message "Kernel headers for version 2.6.32.27-0.2-default were not found". If you installed them in a ...
- 903
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votes
2
answers
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Kernel vs ROOTFS
I think I know but I am a bit confused.
Can someone please explain the difference between Kernel and rootfs in embedded system environment?
- 61
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votes
1
answer
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bash autocompletion is slow, freezing my desktop
sometimes when working with a custom kernel, pressing tab in the bash autocompletes at a horrible pace. It freezes the whole desktop. Then comes back after awhile.
This is the only quirk that I've ...
- 171
5
votes
3
answers
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How to recover the password for a particular user account on my linux pc
I have a linux pc on which several users are configured to login. for the same PC i have the root access (username and password). I have lost one of the user accounts password. How to get back the ...
chaitu
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votes
2
answers
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How to install kernel rc rawhide in Fedora?
I am new to Fedora and I decided to try it on my new laptop instead of Ubuntu. I have an XPS 13 (9343) and the sound is not working. I researched online and found out that people had success ...
- 161
5
votes
1
answer
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Uninstall latest kernel using yum
The latest kernel kernel-3.10.0-229.1.2.el7.x86_64 panics at boot on my CentOS 7 box due to a kernel bug.
Since this kernel is the default in GRUB, if I forget to manually change the kernel selection ...
- 3,424
5
votes
4
answers
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Unmounting Detachable devices (eSATA,USB storage) in Linux
A detachable device like eSATA, USB drive can be abruptly removed (by simply pulling the plug).
If there are open file handles on a partition, then this partitions won't unmount, i.e. the Linux ...
- 51
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votes
3
answers
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Do both lsmod and /proc/modules use the same mechanism to retrieve modules?
I can get a list of modules using either lsmod or cat /proc/modules. Do the two approaches use the same mechanism to retrieve the modules? I want to know this as we could use it to find some hidden ...
- 859
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votes
1
answer
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How does WSL[2] pose limitations on a guest linux system?
As soon as I got WSL2 on my Windows PC, I installed an adapted CentOS 8.2 version. As I explored it, I found that I could read and write in the host's NTFS file system out of the box. It was also ...
- 151
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votes
2
answers
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What is the exact different between Linux kernel release and version? [duplicate]
In Linux based operating system we can find Kernel release and Kernel version. So what is the exact different between Release and Version ?
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Is it possible to boot a consumer i7 system with a Xeon processor and ECC memory?
I have read a couple of blog posts on the Internet that appear to imply one can boot at least some i7 motherboards with unbuffered ECC memory and a Xeon 43xx processor installed.
I can boot my MSI ...
- 111
5
votes
1
answer
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Kernel hacking methodology - how to find out where to hack the linux kernel
I have a throw-away cheap laptop I'd like to twiddle around, a Thinkpad SL 500.
What bothers me are two leds, the one for wireless connectivity, and the one for hibernation, which don't light up at ...
- 173
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votes
1
answer
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High System CPU usage on Linux
We have an unusual problem where some of our Linux servers are going into a state where the CPU utilisation is very high and when we dig down, most of it is in kernel space. The %sys utilisation is 80%...
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votes
0
answers
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/sbin/init exists but couldn't execute it
I'm building Linux from scratch. Currently I have the kernel, glibc and sysvinit. I've compiled everything myself following these instructions. Though my version of glibc is 2.19. Also, I use grub ...
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votes
2
answers
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Is it safe to enable user namespaces in CentOS 7.4 and how to do it?
I am trying to use Brave Browser on my CentOS machine, but when I try running it, it gives me the following error.
[19576:19576:0208/180128.818448:FATAL:zygote_host_impl_linux.cc(126)] No usable ...
4
votes
2
answers
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Compile linux kernel for different machine
I am new to kernel development, and I have to compile a kernel with some specific features and then install it on some machines. The problem is that these machines are slow, and hence I want to ...
- 2,474
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votes
2
answers
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Where are Kernel Headers for Fedora 21?
I'm trying to install VMware on Fedora 21. I've installed the kernel headers:
sudo yum install kernel-headers-`uname -r`
And I receive the following message:
Package kernel-headers-3.18.5-201.fc21....
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4
votes
2
answers
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How do I set up grub2 with Xen?
I am booting a new Xen kernel and it all goes fine up until some point during the boot process when the machine reboots without warning. Unfortunately, I don't see errors flash up just before that ...
- 4,075
4
votes
3
answers
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Pipe kernel messages to another process as they occur
I have an OLED screen on my laptop that I have configured to show status information. The current driver I have installed in Linux for it is able to display messages by sending them to a script as an ...
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votes
4
answers
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What steps do I need to take to compile and install a Linux kernel?
What are the correct steps to compile a Linux kernel? Are these steps the same or different for different kernel versions i.e for 2.2, 2.4 and 2.6.
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