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Questions tagged [linux-kernel]

Questions about Linux kernel and Linux kernel related topics eg. implementation details such as system calls, kernel customization, etc. For Linux user space topics which do not involve kernel details, [linux] or distribution tag are more suitable.

3
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3answers
26 views

Is there a way to get an process exit status after many more commands have been issued in linux?

If I have a lot of commands I've issued and I want the exit status of a process that exited say 100 commands ago. Is there a struct, file location, or variable in linux I can access all of exited ...
1
vote
0answers
11 views

Ubuntu 14.04.5 LTS sends an IPv6 NS message for link-local address for no obvious reason

After sending an ICMPv6 echo request message to random global address, my router sends my PC a Neighbor Solicitation message in order to make an association between its link local IPv6 address and a ...
-1
votes
0answers
21 views

How to update the version of kernel when I use petalinux?

I use petalinux-v2015.4 and the kernel version is xlinx-4.0. I would like to change the kernel, for example, upgrade it to version xlnx_rebase_v4.14. What type of work I should do, and how can I do ...
-1
votes
1answer
22 views

Is it better to use gcc and kernel that comes with OS or a newer one [on hold]

Centos has 3 years old gcc, with also 4 years old kernel. Is it better to use the old gcc and kernel or is it better to upgrade the kernel and gcc?
0
votes
0answers
46 views

What are the relations between a kernel control path a kernel thread?

Understanding The Linux Kernel says: A kernel control path denotes the sequence of instructions executed by the kernel to handle a system call, an exception, or an interrupt. and Besides ...
0
votes
1answer
38 views

What are the implication of iommu=soft?

I've got new laptop at work (Lenovo A485) and there are few issues with it. It prints AMD-Vi: IOAPIC[32] not in IVRS table and kernel panic after that. So far I've figured few ways to get the system ...
0
votes
0answers
48 views

How to downgrade Debian 9's Kernel to 2.6.32? [duplicate]

I would like to downgrade Debian 9's Kernel to version 2.6.32, because this older version will properly works with some hardware I use. I tried using an older version of Debian but as many had said, ...
1
vote
2answers
53 views

Reading Linux kernel documentation in terminal

Is there a way to read Linux Kernel documentation offline in the terminal? For exmple, I am reading this document online: https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt If I use Linux ...
2
votes
1answer
47 views

Explanation for Linux kernel [closed]

I would like to understand the meaning of the term Linux Kernel and the various types of kernel. For example, I would like to know what is the difference between Microkernels and Monolithic Kernels. ...
2
votes
1answer
25 views

Do the virtual address spaces of all the processes have the same content in their “Kernel” parts?

The Linux Programming Interface shows the layout of a virtual address space of a process: Is the kernel in the physical memory completely or partially mapped to the part "Kernel" on the top from ...
0
votes
0answers
14 views

Remove kernel modules physical address randomization

I'm trying to build a Kernel integrity checker for ARM 64 architecture. The check is done from an hypervisor, so the translation table of Linux is not available. This is why I need to access the ...
2
votes
1answer
18 views

init boot mount: mounting /root on /root.ro failed: Invalid argument, aufs

I am trying to set up a read-only filesystem at /root directory on my embedded device. I have following in code in my boot init command file /sbin/init-overlay: rootmnt=/root ro_mount_point="${...
1
vote
1answer
21 views

Linux kernel compiling - What's the meaning of #6 SMP

Every time I recompile the kernel, the kernel build number changes a little. file arch/x86/boot/bzImage Linux kernel x86 boot executable bzImage, version 4.18.6 (b00m@acer) #6 SMP Thu Sep 13 09:46:...
0
votes
0answers
29 views

Installing older kernel for older hardware vs Installing old distro version

I have an old IBM Think Centre computer, with a 3Ghz Pentium IV Processor. I bought it as a refurbished computer. I used it as a webserver a few months but now I want to use it as my personal computer....
0
votes
0answers
33 views

What subsystems in Linux do their own management of physical pages?

Operating System Concepts says Two other main subsystems in Linux do their own management of physical pages: the page cache and the virtual memory system. I was wondering what the subsystems in ...
1
vote
1answer
23 views

How to access NVRAM and DPRAM in Linux userspace?

We are going to add NVRAM and DPRAM in our custom board where both of them will be mapped in system memory map. I am not getting a clue that whether these devices have some generic drivers in Linux ...
1
vote
1answer
29 views

Is it possible to use Arch without installing the base package?

Is it possible to use Arch without installing the base package?  If not, why is the base package not part of the installation image?
19
votes
1answer
767 views

disable kernel module which is compiled in kernel (not loaded)

My server has two 1-Gbit and two 10-Gbit onboard network cards. I need to disable the 1-Gbit network cards completely, so that ifconfig -a does not show them. The network cards use different kernel ...
-1
votes
0answers
19 views

How to enable a particular flag in the configuration file after installing the kernel?

I was trying to enable one of the flag for the kernel while installation. I followed these steps. cd linux-4.18 make localmodconfig and pressed enter for all. Then added the flag(CONFIG_COMPILE_TEST=...
1
vote
1answer
26 views

How exactly a 'shutdown -h' “HALT” differ from “normal shutdown” in linux [duplicate]

Suppose I have 20 process/deqamons running in my linux system, How different the HALT will have an effect on my process/deamons, when compared to a normal shutdown.., *Note: I need to understand.....
1
vote
0answers
36 views

How do I verify linux kernel signature with gpg?

Following the notes at the kernel.org site, but I cannot seem to verify the signature of the kernel. I tried to use the given script to handle it for me, but that has failed too. user@localhost ~ $ ...
2
votes
1answer
82 views

Ubuntu 18.04 does not use more than 32GB of RAM [closed]

I have just upgraded my PC with another 32GB of RAM. Both BIOS and lshw does acknowledge the existence of all four 16GB RAM modules, but neither free, top and htop sees the actual memory. $ sudo lshw ...
5
votes
1answer
82 views
+50

AMD microcode not updating

I have recently installed Gentoo Linux on my AMD Ryzen 7 1700X. Now I face segmentation faults during heavy compilation loads and also random restarts in an idle state. As a very first step I ...
1
vote
0answers
17 views

Which kernel `.config` option causes kmsg/dmesg message: “Switched APIC routing to physical flat.”

I've recompiled the Linux kernel (4.18.5) with minimal .config options and I've noticed that, compared to when booting the previous kernel, I'm now missing the dmesg line: Switched APIC routing to ...
2
votes
1answer
45 views

How to fix “File” *.service “configures an IP firewall (IPAddressDeny=any), but the local system does not support BPF/cgroup based firewalling”?

Booting from a kernel which I recompiled with a custom .config, I got the the following kmsg(ie. dmesg) message: systemd[1]: File /usr/lib/systemd/system/systemd-journald.service:35 configures an ...
0
votes
2answers
44 views

What is an example of an “external user process”?

I'm currently studying for my LFCS and have reached a section regarding the difference betwen user-created processes and kernel-created processes. Inside kernel-created processes, they define two ...
0
votes
1answer
10 views

Installing a kernel rpm package in Qubes OS complains: dracut-install: ERROR: installing '/usr/lib64/plymouth//label.so'

$ sudo dnf install kernel-latest-4.18.5-8.pvops.qubes.x86_64.rpm kernel-latest-devel-4.18.5-8.pvops.qubes.x86_64.rpm Qubes OS Repository for Dom0 ...
0
votes
1answer
25 views

Which kernel .config option causes “Magic number: 1:252:3141” on dmesg?

Here it is in context: [ 0.507474] i8042: PNP: No PS/2 controller found. [ 0.507568] mousedev: PS/2 mouse device common for all mice [ 0.507683] device-mapper: uevent: version 1.0.3 [ 0....
21
votes
2answers
3k views

Is the PID of a child process always greater than the PID of its parent on Linux?

Let say, from kernel 2.6 onwards. I watch all the running processes on the system. Are the PID of the children always greater than their parents' PIDs? Is it possible to have special cases of "...
3
votes
2answers
89 views

How to change the length of time-slices used by the Linux CPU scheduler?

How can I increase the length of time-slices, which the Linux CPU scheduler allows a process to run for? I want to reduce how frequently the kernel will force a switch between different processes ...
0
votes
2answers
44 views

What does “DP” device stand for?

I'm trying to list the connected monitors using xrandr that is returning the following information: Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192 eDP-1 connected primary ...
1
vote
0answers
19 views

How can I clear active NFS client-side server/volume entries that have become disassociated with any mounted filesystems? [duplicate]

I have a situation where server-side mountpoints sometimes don't show up over NFS with a certain glitchy server. Typically restarting nfsd and/or fiddling with /etc/exports fixes things, but today ...
-1
votes
1answer
106 views

Recompile a kernel including a firmware

How can i recompile the kernel? I' m trying this guide https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel. I' m using lubuntu 18.04 on a tablet, i want a custom kernel to enable the touchcreen. ...
1
vote
1answer
91 views

Why does the Linux kernel support “umount /”?

Why does Linux support this: umount / Why would anyone write that, instead of this: mount / -oremount,ro I'm looking at the kernel code here: if (&mnt->mnt == current->fs->root.mnt &...
15
votes
1answer
418 views

How to change Linux context-switch frequency?

How is it possible to change the Linux (linaro, ubuntu, debian) context-switch frequency? I am okay for trading-off a less-responsive system for a more efficient one. EDIT1: I have a main process ...
0
votes
0answers
28 views

Production server with Debian Jessie (system hangs after an invalid opcode)

I use Debian Jessie on a Xen Server 6.2 since many years without problem. I update Jessie regularly.. since some days, there is a fatal bug. Aug 31 13:49:46 git kernel: [139139.936636] ------------[ ...
0
votes
1answer
19 views

Configure kernel with fault-injection enabled

I'm trying to use the Linux fault injection framework to simulate faults. I'm using ubuntu 16.04 LTS (4.15.0-33-generic), but i didn't find any way to "activate" the FI framework. How do I configure ...
5
votes
1answer
104 views

Ubuntu 14.04 32 bit swapfile max 60k issue

Have a strange issue where suddenly all my swapfile (1gb each) get truncated to only use 60k . I can remove/recreate etc but whatever i do , the max seems limited to 60k with following message in ...
0
votes
0answers
30 views

TCP RST flag (windows vs linux)

I have broken client who I need to serv, and I can't change it or affect it in any way. I put same software serwer on windows and on linux. Windows is working, linux is not. After analyzing I figured ...
0
votes
1answer
16 views

What's the difference between difference between NF_NETLINK_CONNTRACK_EXP_DESTROY and NF_NETLINK_CONNTRACK_DESTROY?

I have a Netlink socket, subscribed to destroy events, by using bind with NF_NETLINK_CONNTRACK_DESTROY OR'd into the groups parameter. When looking through the nfnetlink_compat.h, though, I see that ...
0
votes
0answers
14 views

container_of sample code in lwn.net [migrated]

When seeing: void my_object_release(struct kobject *kobj) { struct my_object *mine = container_of(kobj, struct my_object, kobj); /* Perform any additional cleanup on this object, then... */ ...
0
votes
1answer
46 views

Unix STREAMS vs Standard Streams [closed]

Can somebody explain differences between those mentioned in the title? Both are called "streams", however, their function seem to be quite different.
1
vote
2answers
72 views

CentOS 7: Kernel version has no module directory

I'm trying to compile and install a kernel. After download the code and configure the installation I have executed succesfully these comands: # make bzImage # make modules # make But when I try to ...
0
votes
1answer
43 views

Why can't the Linux preemption model be changed by kernel parameter? [closed]

The Linux kernel has a large set of parameters that enable users to adjust the kernel behavior without recompiling it. There doesn't seem to be a parameter to adjust the preemption model: -*- ...
-1
votes
2answers
94 views

How do I roll-back to a previous Ubuntu kernel? (running Ubuntu 16.04)

I have a VPS server with a hosting company that I have ssh/root access. I recently tried to upgrade the kernel to the latest (4.18.5-041805-generic). I was running 4.4.0-169 and thought it was time to ...
0
votes
2answers
35 views

Is there a way to see the remaining battery life of your keyboard/mouse on Ubuntu/Linux?

I am just wondering. KDE sends me a notification if there is 10% battery life left on my keyboard, which is wireless. But is there a way to get the whole battery status data?
-1
votes
1answer
58 views

Terminal commands not working

I moved all files starting with lib from /../ to some folder as, mv /../lib* /to/some/folder after which I can't move it back.It comes as -bash: /bin/mv: /lib64/ld-linux-x86-64.so.2: bad ELF ...
2
votes
1answer
25 views

USB device authorization: Difference between interface_authorized_default and authorized_default

What is the difference between /sys/bus/usb/devices/usbX/authorized_default and /sys/bus/usb/devices/usbX/interface_authorized_default? Basically, both of the files are responsible for denying access ...
-1
votes
2answers
41 views

What do Linux upgrades provide?

Relatively often there are new kernel upgrades. But every time I install them, I do not see any difference between before and after. What do they exactly provide? How can I feel their presence on me? ...
0
votes
0answers
13 views

How are two i2c drivers linked together

I followed this tutorial and everything is working fine When I run lsmod, it lists the ina2xx-adc driver (not the ina2xx driver) as running. After I do $ echo 'ina219 0x40' > /sys/bus/i2c/...