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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.

11
votes
1answer
477 views

Why is my Debian 9 (Stretch) Linux kernel not getting upgraded after 'apt install'?

I spent the better part of the month trying to install, reinstall, delete manually, and reinstall the latest linux-image-4.9.0-8 (or thereof) onto my Debian 9 (Stretch), but it will always (re)...
0
votes
0answers
9 views

Tcp TCPBacklogDrop and packets pruned from receive queue

I am analyzing two virtual machines in the same LAN, tcp packet loss problem, but the knowledge has been exhausted. platform CentOS Linux release 7.2.1511 (Core) 3.10.0-327.el7.x86_64 #1 SMP Thu Nov ...
0
votes
1answer
41 views

How to restore a deleted file while it's still being opened?

I tried xtricman⚓ArchVirtual⏺️~🤐ls /proc/self/fd/ -l Total 0 lrwx------ 1 xtricman users 64 1月 16 16:34 0 -> /dev/pts/0 lrwx------ 1 xtricman users 64 1月 16 16:34 1 -> /dev/pts/0 lrwx------ ...
1
vote
0answers
24 views

Order of kernel upgrade commands for gentoo

I have simple bash script to update the kernel. It includes building the kernel, rebuilding external modules, building initramfs with genkernel and updating grub config, here is the script: #!/bin/...
0
votes
0answers
15 views

Divert incoming network traffic for a single Ethernet Interface card (NIC)

I have one/single network card and I want to divert the incoming traffic to 2 different applications (app1, app2). One application will follow the normal TCP/IP Stack while the other application must ...
0
votes
0answers
19 views

memory.max_usage_in_bytes is 0

I have one system with a non zero /sys/fs/cgroup/memory/memory.max_usage_in_bytes value and another with a value of 0. I think they have the same kernel config and boot args. Is there a cgroup ...
1
vote
0answers
37 views

kexec: relocate_kernel fails

I am not able to get kexec to work. For x86_64 relocate_kernel fails to store information for jumping back. Kexec stops in movq %r9, CP_PA_TABLE_PAGE(%r11).
0
votes
0answers
33 views

can't load iwlwifi nonfree firmware after kernel update

My hardware requires the iwlwifi nonfree firmware for working wifi. With the latest kernel version however it stopped being able to load it. The last working version is 4.9.0-7 while 4.9.0-8 does not ...
1
vote
1answer
20 views

Tracking dependency loop in kernel/kconfig

I'd like to track a dependency loop in the linux kernel kconfig setup. When compiling with gcc-6.3 I can do the following without no issues: $ make ARCH=powerpc custom_defconfig $ make ARCH=powerpc ...
3
votes
1answer
55 views

How are GCC versions chosen for compiling the linux kernel?

I know that the linux kernel specifies minimal compilation requirements, but I haven't found any source of information regarding how distros/vendors choose which version of GCC to use when compiling ...
2
votes
2answers
43 views

USB Device not responding to set address

I have a built-in USB device that is not responding to setup address. It tries to set the device up continuously and fails continuously: wasting battery, CPU, disk space, etc. Is there a way to kill ...
5
votes
0answers
93 views

Why does one kernel work, but the other doesn't, when they are identical to the byte? [closed]

I have a couple of scripts, that build Linux live CDs for me. I have a couple of kernels, that I built myself to use for these. Having built one such Live CD a couple of weeks back with a kernel, ...
0
votes
0answers
32 views

Linux programming: Compile code with dependencies [migrated]

I am new to linux programming and learning it from The Linux Programming Interface by Michael Kerrisk. I have to compile my first program that has dependencies. Directory structure: --linux-...
0
votes
2answers
45 views

What is the name of the website that has the searchable linux kernel files?

I don't mean where can I download the kernel. I don't mean kernel documentation either. I mean I know there is a website where I can flip through/search through the source code of the linux kernel, ...
1
vote
1answer
40 views

NUC with Centos 7 crashing: Microcode SW Error Detected

I am trying to figure out why the WiFi on my Intel NUC with CentOS 7 continues to die. As info, I have 5 node Hadoop cluster and they are all configured the same (as far as I can tell), however, the ...
0
votes
0answers
36 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 ...
1
vote
1answer
30 views

Enable core dump on Linux 2.6.35

I'm running kernel 2.6.35 on a custom embedded device (ARMv7). I'm trying to get a core dump but it appears core dumps are disabled. My kernel config can be found here: https://pastebin.com/XXZ8YyaA ...
0
votes
0answers
29 views

ADMA error after mounting root partition

We are trying to boot Linux on a custom board based on ARM processor. The kernel executes successfully from both SD card and eMMC but when the kernel tries to mount the root file system, it is able to ...
0
votes
0answers
15 views

troubleshooting nonstop “No irq handler for vector” kernel messages

One of my servers is constantly spitting errors that look like the following: The rate is frequent and mostly regular... I get very clear frequency spikes at intervals of 6, 16, 23, and 40 seconds ...
2
votes
1answer
69 views

Does Linux kernel check file permissions on inode or open file description?

I wrote this testing code, and find that this program can always read the file successfully even after I canceled the read permission when running getchar(). #include <stdio.h> #include <...
3
votes
2answers
265 views

Is it possible to activate the watchdog on any Linux machine?

On an Orange Pi Zero running a Raspbian server, it's possible to use the watchdog very easily just by running the command echo 1 > /dev/watchdog as root. The idea is that the system will certainly ...
0
votes
1answer
67 views

Is locale also supported by the Linux kernel?

In Linux, timer is supported by kernel. Time is relate to locale. Is locale also supported by the Linux kernel, or a user-space construct; the kernel doesn’t care about that? Thanks.
0
votes
2answers
34 views

Are tgid and pid ever different for a process or lightweight process?

tgid and pid are the same concept for any process or for any lightweight process. In /proc/${pid}/status, tgid and pid are distinct fields. Are tgid and pid ever different for a process or ...
0
votes
1answer
32 views

removing redudant kernal libraries after kernal reinstallation

I'm learning to administer a VPS which has an openVZ kernel (= go easy...). I thought I'd attempt to load a missing kernal module by reinstalling my kernel with: sudo apt-get install -y linux-image-$(...
1
vote
2answers
107 views

Does Linux not distinguish between processes and threads?

As far as I know in 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 groups of ...
0
votes
1answer
31 views

Black screen after Login Fedora 29

Seems like i today updated my system. After system reboot i can see Login screen. But after login with my user, booth screens turn in black and after ~30-45 seconds i get kicked back to login screen. ...
0
votes
1answer
52 views

Scan network with Linux kernel command

Does Linux kernel provide some utility familiar to nmap for simple network scanning to discover attached nodes?
1
vote
1answer
34 views

How does Linux Kernel switches from kernel stack to interrupt stack?

What happens when a user mode task is interrupted ? I know for a fact that the CPU switches to the kernel mode stack by refring the TSS. But when and how does the kernel switches to the IRQ stack?
1
vote
1answer
56 views

VFS: Cannot open root device mmcblk1p1 or unknown-block(179,33)

I am trying to run Linux on custom board based on Nvidia TK1. When I try to boot the board from SD card, I get following error: VFS: Cannot open root device "mmcblk1p1" or unknown-block(179,33): ...
3
votes
2answers
92 views

Why does the Linux kernel build system use incremental linking or ar T thin archives?

While studying the kernel build system, I noticed that before v4.19 the kernel was using incremental linking (ld -r) and then it moved to thin archives (ar T) as shown at: What is the difference ...
0
votes
1answer
26 views

Secondary password file creation and reset

Is there any way to reset all passwords previously created when the secondary password file is enabled for the first time to ensure higher-level protection ?.
0
votes
0answers
19 views

How is CVE-2016-6787 a UAF bug in Linux kernel? [migrated]

From the explanation video of the Linux kernel vulnerability CVE-2016-6787, I don't understand is though put_ctx isn't inside a mutex, there's an atomic_dec_and_test inside put_ctx at the very ...
0
votes
0answers
31 views

command fialed: operation not supported (-95) while enabling monitor mod [duplicate]

I bought a dongle which are Realtek 8812AU and I'm sure that the dongle could work on monitor mode but after I connected it to my kali Linux on virtual machine and I trying to enabled monitor mode, ...
1
vote
2answers
60 views

Where is the network data is stored on linux system?

is there a way I can find information about my wifi connections? Which networks I was connected to and when? I had tried to look for this information under proc/net but found nothing. (To be more ...
3
votes
0answers
54 views

Kernel BUG: unable to handle kernel paging request

So I'm trying to run this kernel module on my laptop, and every time I do so, I get a stack trace that looks like this (all the messages might not be relevant to the module). [17539.035247] EBBChar: ...
-1
votes
0answers
32 views

Inactive session timeout for GUI and Terminal [duplicate]

How inactivity timeout for GUI session is set for 15 min ?. Once a user's session is locked or terminated, the product must force the user to re-authenticate before continuing his or her session. ...
1
vote
1answer
19 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 ...
0
votes
0answers
21 views

USB keyboard sometimes does not work on boot

I just installed Arch on a new motherboard and sometimes when I boot the machine the USB keyboard does not work. If I unplug it and plug it back it, then it works. Any way to fix a problem like this?
0
votes
0answers
10 views

Range of values of virtual runtime in CFS scheduler

I am trying to understand the working of the Linux CFS scheduler using kernel version 4.19.2. As mentioned in the documentation, it does not use timeslices in the traditional way but uses the concept ...
1
vote
0answers
25 views

Linux kernel does not handle orphaned sockets, why not?

This was originally posted to serverfault but was voted as off topic by the community. Let me just preface this question by mentioning I understand the why/how/where/when of the Linux kernel socket ...
1
vote
3answers
76 views

Turn off CPU turbo-boost for a process

When the CPU (Intel i5-8400) is heavily loaded, the fan seems to increase its speed and make noise. I want to eliminate the noise when running CPU-intensive backup process (backup2l program). (It is ...
0
votes
1answer
29 views

Alsa and alsactl: init, store and default configuration of control file

The target kernel is: 2.6.35.14 (old) and its running on an embedded platform and the codec is a wm8753. I am trying to understand how the alsactl system works. I found a file asound.play @ etc/alsa ...
0
votes
0answers
19 views

How to build existing kernel modules from github “linux/drivers/”

I want to load kernel modules using modprobe. However, because I don't have the .ko-file yet, I need to build them before. In my case the one I want would be in the path /lib/modules/$(uname -v)/...
1
vote
0answers
8 views

correct circular buffer API usage [migrated]

I need to correct circ_buf.c which gives out these long errors ? The most common error is error: invalid type argument of unary ‘*’ (have ‘int’) For more context, please see this reddit thread /* *...
0
votes
0answers
25 views

Changes to Linux driver `pinctrl-amd`

HP Envy x360 with AMD processors has a long list of issues with Linux support. I am trying to fix the one related to touchscreen. New kernel versions already include the patch provided on Bug 198715, ...
-1
votes
0answers
83 views

Linux kernel can't seem to find and run my init file?

I'm almost at my wits’ end working on trying to get my initramfs to work on my Linux kernel.  I've tried passing the initramfs through the bootloader, I've built it into the kernel itself, I've ...
0
votes
0answers
15 views

Porting pre-4.15 timer code for mali450 GPU kernel driver on ARM64 [migrated]

I have an old TV box based off the Amlogic S905X ARM64 SoC, a Tanix TX5, which originally ran Android on it. I don't like being locked out of the potential of my hardware, so I followed closely the ...
0
votes
1answer
59 views

Why OS needs explicit support for musl?

Kernel has API based on interrupts and magic numbers. This API is too low-level and unfriendly for programmers, so libcs were invented. They expose functions, which are handy and call kernel API ...
1
vote
1answer
79 views

IPsec VPN using linux kernel 2.6

I'm trying to implement mip6d on my laptop using debian9 but I have to downgrade to an older kernel linux (linux 2.6) to install de racoon2 (software that allow exchanges and installs of security ...
1
vote
1answer
43 views

How many page table the linux kernel maintains?

the kernel maintains a data structure, called a page table, that contains a mapping of a processes' virtual page addresses to real page addresses in memory. I read a book with the sentence above, I ...