Questions tagged [kernel]
Everything about Unix kernels: development, configuration, compilation, design, etc.
3,544
questions
1
vote
0
answers
24
views
AM335X setting of RNG
I kindly request any advice regarding the configuration of the HW RNG of TI AM335X. I'm aiming to achieve security certification for our device, which is based on the PLC Wago PFC200 750-8217. One of ...
- 11
1
vote
2
answers
46
views
Building custom kernel on Ubuntu Jammy
Someone on Reddit showed me this yesterday
https://git.kernel.org/pub/scm/linux/kernel/git/westeri/thunderbolt.git/commit/?h=next&id=9a966517a83090ee3e26e9a93a92523e2358c5b3
Looks like I should be ...
- 11
0
votes
1
answer
20
views
Boot a kernel of debian installer with expert mode
I want to reinstall my VPS with the debian's official repository, instead of with the image provided by the VPS operator(I don't trust the VPS operator).
On original system I installed debian-...
- 163
0
votes
0
answers
11
views
kdump won't save dmesg in CentOS stream 8
I created a CentOS 8 stream machine on aws, and configured crashkernel in grub
$ cat /proc/cmdline
BOOT_IMAGE=(hd0,msdos1)/boot/vmlinuz-4.18.0-552.el8.x86_64 root=UUID=e52ef623-609b-4202-9b2c-...
- 54.6k
0
votes
0
answers
21
views
Is it possible to read page table in Linux with unprivileged mode?
this is my very first question in Unix & Linux, I'm currently learning about virtual memory.
I am appreciating this awesome paper drammer (CCS'16). Where it fools the buddy allocator to allocate a ...
- 1
-2
votes
2
answers
61
views
Where is 512M RAM from?
In Virtual machine, Kali, I assigned the memory 4G, like this;
But there is a problem.
I installed self-build kernel at the guest to hack the memory.
# uname -a
Linux 15ud490-gx76k 6.8.4+ #8 SMP ...
- 83
0
votes
1
answer
34
views
Is it possible to set larger buffers for file access on linux
I have a process thats reading the whole filesystem and hashing files. It slows down (by 4x or so) because the reads are causing a lot of seeking. Small chunks of each file are being read by each of 4 ...
- 133
6
votes
1
answer
584
views
Does mmap() update the page table after every page fault?
Based on my research on mmap(), I understand that mmap uses demand paging to copy in data to the kernel page cache only when the virtual memory address is touched, through page fault.
If we are ...
- 63
0
votes
0
answers
18
views
How to "wake-up" user space threads from kernel?
Suppose you have a kernel device driver receiving data and a user space threads waiting for the data.
You want to avoid wasted cycles by having the user space thread block and wake-up once the kernel ...
- 165
2
votes
1
answer
337
views
VMware vmmon & vmnet 17.5.1 and Linux kernel 6.8.0 won't compile
After upgrading to kernel 6.8.0,
VMware's vmmon and vmnet couldn't compile, giving the following error:
...
...
/tmp/vmware-host-modules-w17.5.1/vmmon-only/common/task.c:548:1: warning: no ...
- 151
1
vote
1
answer
47
views
cgroup virtual file system is read only for root, when root has write privileges?
As the title of my question suggests, I am trying to edit the properties of my cgroup virtual file system - create new directories, edit the resource limits in certain files, etc - but any write ...
- 33
21
votes
1
answer
3k
views
How could March 30th 2024 be followed by the 1st?
I am in the EU zone +1 or when DST is on, +2. Now is Sunday 31.3.2024. This Sunday morning, we changed into DST, at 2→3 (CET → CEST).
I have Linux servers in separate networks reporting monthly energy ...
- 466
2
votes
0
answers
47
views
High resolution sleep in kernel thread?
What is the correct way to sleep to us resolution in a thread?
I'm trying to write a device driver and I need to keep a pin high for a certain number of us after a GPIO interrupt.
My plan is to create ...
- 165
0
votes
1
answer
40
views
What does the "segfault at X" kernel log message mean if X is very large?
I've got a device with bad RAM. Running memtest overnight shows all faulting addresses to be in the 0x7d0000000 - 0x7f0000000 range. I plan to replace the RAM, but until then, I've disabled a 2GB ...
- 113
4
votes
1
answer
96
views
When (and how) are file permission/access decisions made in kernel space?
(I think) I have a relatively good understanding of how Linux permissions work - traditional Unix DAC permissions, and how they're represented, security context in relation to processes (i.e. cred ...
1
vote
0
answers
46
views
Is there a known linux kernel bug with two threads incorrectly getting back the same file descriptor number?
I've got a multithreaded program in which a sem_open with O_CREAT occasionally fails with EBADF. This is on an ARM linux 4.9.88, from NXP, on an embedded device.
It is very difficult to reproduce, ...
- 111
3
votes
2
answers
103
views
How does the Linux Kernel store hardware TX and RX filter modes?
I am working on a C program which gets the timestamping information for a given network interface, like my own version of ethtool. My goal is to get the information printed by $ ethtool -T myNetIf. ...
- 63
1
vote
1
answer
41
views
Where do i trace NVME IO within the Linux driver?
I want to write a small Linux driver extension. More specific: I want to write all the communication between the host and a M.2-nvme-ssd into a userspace file. The nvme driver is pretty big though and ...
- 13
0
votes
0
answers
20
views
How to disable kernel_lockdown (MSR) without BIOS or console access
I have a laptop with a damaged screen. I use it by connecting a screen via HDMI. I'm running some cryto mining software that requires MSR access to run efficiently.
I cannot access the BIOS to disable ...
1
vote
0
answers
90
views
Home Server/NAS Plagued by random crashes
I'm here to get help for an issue which has been plaguing me for a year. I'm using HP Elitedesk 800 G3 i5-7500 as my Home Server/NAS.
I have the latest Debian 12 (Bookworm) on it. I'm running my ...
- 11
-1
votes
1
answer
79
views
"Error! Installation aborted" - dkms problem when installing or upgrading
When I tried to install something from GitHub or even update and upgrade the system, the error message shown below is displayed. This is on the Kali distribution. The problem is related to the Realtek ...
0
votes
0
answers
16
views
Yocto. How to keep u-boot splash screen and then how to keep kernel splash screen on
I am porting Yocto into my board. I wrote u-boot & kernel graphics drivers for my display. Everything works fine. The only problem I have is:
u-boot splash screen is displayed for a while when ...
- 101
0
votes
0
answers
18
views
Docker on visionfive2 risc-v
Docker on visionfive2 risc-v
user@starfive:~$ sudo dockerd
WARN[2024-03-02T13:08:27.753708638Z] Unable to find memory controller
WARN[2024-03-02T13:08:27.753772888Z] Unable to find io ...
- 1
1
vote
0
answers
40
views
Laggy PC with Kernel 6.5 and AMD 5500U Lucienne
I am currently facing a problem with my Lenovo E15 laptop (AMD Ryzen 5500u "Lucienne" processor) and the kernel 6.5. (Xubuntu 22.04)
Maybe three weeks ago,
I noticed that my computer was ...
1
vote
1
answer
67
views
Multiple distros crash and reboot when trying to resume from sleep/suspend on laptop
Gigabyte Aorus 15 XE4. Nvidia RTX 3070ti. After multiple attempts, this doesn't seem to be related to Nvidia Drivers or intel/nvidia optimus like I thought based on many people with a similar issue. (...
- 111
0
votes
0
answers
31
views
Alpine Linux 3.18.3 - Kernel pinning during installation
I'm a new Alpine Linux user and I'm struggling to install a specific kernel version on Alpine-virt-3.18.3-x86_64. The ISO I'm using comes with the default kernel version 6.1.43-0-virt. When I run the ...
- 1
0
votes
1
answer
17
views
drm-kmod-20220907_2 not supported for this configuration / NVIDIA : Failed to initialize the NVIDIA kernel module
I need to conduct some tests on top of the FreeBSD 13.1.
So,I've installed it on one of my disks. I've installed xfce4 and KDE,Xorg and from the ports (after having upgraded them).
I've installed the ...
- 531
1
vote
0
answers
26
views
Completely confused with vmstat
So, from what I've found, there are multiple versions of vmstat out there for various OSes like Linux, BSD, and Solaris. I'm referring to Linux's vmstat procps-ng 3.3.17 .
Now, to be more specific, ...
- 11
0
votes
0
answers
21
views
systemtap script to simulate the IO error failed
I was trying to simulate the read/write error on specific sectors of the volumes by using the following systemtap script
global error_sector_start
global error_sector_end
global error_major
...
- 1
0
votes
0
answers
16
views
Linux kernel support of old(er) Radeon GPUs
I have a Radeon RX 6700XT and it works flawlessly in Linux.
I am looking at getting an older Radeon card and was wondering what is the support for something like a Rx 460.
Is it native as my beefy ...
- 873
0
votes
0
answers
22
views
Repeated crashes on Debian 10
I have a dedicated machine in my garage running LinuxCNC on Debian 10. Recently it's been having repeated crashes and rarely lasts longer than 30 minutes before freezing. I've tried Ctrl-Alt-Del and a ...
1
vote
0
answers
30
views
EVE-NG installation missing build folder from /lib/modules/kernel
I have EVE-NG ISO installed on a laptop and I'm trying to install a realtek driver for the wifi-card and I have to use 'make' to compile the code.
'Make' fails with the error message: "/lib/...
- 11
0
votes
1
answer
38
views
Debian file corruption bug possible without reboot after unattended kernel update?
Today I learned that there had been a faulty Debian kernel version which caused ext4 data corruption (bug 1057843) in December 2023.
Searching through the /var/log/aptitude and /var/log/apt logs, I ...
- 420
0
votes
0
answers
253
views
nvidia-driver-515 throws error on kernel 5.15 inside Ubuntu 22.04
I am trying to install CUDA 11.7 on Ubuntu 22.04.4 LTS. Based on the official documentation, kernel 5.15 is supported for Ubuntu 22.04. However, when I tried installing cuda, the installer throws the ...
- 143
0
votes
1
answer
24
views
Why don't devtmpfs populate /dev/pts?
Linux automatically populates a devtmpfs with the right devices and directory structure. This provides an almost complete tree for /dev, but the pts devices are notably missing.
For the pts devices, ...
- 123
0
votes
0
answers
34
views
Why is the "psci-cpuidle" cpuidle driver not used?
On my Raspberry Pi 5, I noticed that /sys/devices/system/cpu/cpuidle/current_driver contained none.
So I got the latest kernel sources from here and enabled CONFIG_ARM_PSCI_CPUIDLE in menuconfig.
...
- 25
0
votes
0
answers
48
views
How to use the L4 Microkernel with a FreeBSD userland
I'm trying to understand how to use the L4 Microkernel with a FreeBSD userland. I've asked the same to a L4 developer,but he told me that he does not know FreeBSD,so I'm here to ask the same question. ...
- 531
1
vote
1
answer
2k
views
Debian 12.5 kernel fails to install
Just tried to upgrade to the new Debian Bookworm point release 12.5 But...
Building module:
Cleaning build area...
env NV_VERBOSE=1 make -j4 modules KERNEL_UNAME=6.1.0-18-amd64............................
- 131
1
vote
0
answers
90
views
Custom Linux kernel build fails at loading initial ramdisk
I have been trying to build my own Linux kernel, but it keeps hanging after Loading initial ramdisk... I am currently using Arch linux, and have tried several different configs.
I tried both the 6.8-...
- 11
0
votes
1
answer
36
views
Documentation of /sys/block/*/device/type
Where is documentation of /sys/block/*/device/type ?
I need information about this file .
cat /sys/block/*/device/type
0
0
5
what is this numbers meaning ?
- 308
0
votes
0
answers
17
views
Sporadic zombie and D state processes on server
I'm writing to seek your expert advice regarding a critical issue affecting my ThinkSystem SR630 V2 server running AlmaLinux 8.9 (kernel 4.18.0-513.9.1.el8_9.x86_64). It hosts two virtual machines on ...
- 543
1
vote
0
answers
31
views
Why can't linux use $ORIGIN to find the loader (aka interpreter)
When compiling a binary on Linux there's this thing called the RPATH, which tells the dynamic loader where to look for the shared objects. What I like about the RPATH is that you can vendor a ...
- 11
0
votes
1
answer
46
views
ESP and GRUB instalation
The aim is to install Debian using debootstrap. First I want to install all system on a small 32GB flash disk.
And concepts of GPT partition tables and GRUB is quite clear: There is a table of ...
- 105
1
vote
1
answer
78
views
What is header-data split and why it's needed for TCP_ZEROCOPY_RECEIVE page alignment?
I'm currently investigating about TCP_ZEROCOPY_RECEIVE and I read that it requires header-data split support of NIC.
As far as I understand, this feature is to DMA the header (IP, TCP headers) and ...
- 11
0
votes
1
answer
59
views
CentOS 7.9 not reporting full version number after recompiling kernel
I needed to enable SCSI support in CentOS 7.9 so I followed the instructions here:
https://wiki.centos.org/HowTos(2f)I_need_the_Kernel_Source.html
to add SCSI support and recompile, which worked as ...
- 3
0
votes
0
answers
132
views
The problem with building the linux 6.7.1 kernel
I'm starting to build the make -j4 kernel. Then it gives you this error:
LD [M] net/mac802154/mac802154.ko
LD [M] net/dns_resolver/dns_resolver.ko
LD [M] net/ceph/libceph.ko
LD [M] net/...
2
votes
1
answer
234
views
Differences between qemu-i386 and Linux IA32 emulation
On x86-64 Linux, there are two options for running 32-bit applications: one can be built into the kernel itself via the option CONFIG_IA32_EMULATION (normally on for most kernels), and the other is ...
- 123
0
votes
0
answers
24
views
How to trace DMA transactions by using dma_debug?
I am currently working on some PCI-e device stuff, that requires me to get the trace for DMA transactions on a specific (say GPU or NIC ) PCI card. After doing some research I found a useful post by ...
- 1
-6
votes
2
answers
76
views
How to build your own linux? [closed]
I wanted to make linux distro just for fun. i was thinking on what i could base it of can you suggest some propositions and pri time/tools that will allow me to make it ?
1
vote
1
answer
479
views
Can only boot into Ubuntu if I choose 6.2.0-39-generic or 6.5.0-14-generic (recovery mode)
I can only boot into Ubuntu suddenly if I choose either 6.5.0-14-generic in recovery mode or 6.2.0-39-generic normally. But this setting does not persist so I have to enter GRUB everytime I start the ...
- 435