Questions tagged [kernel]

Everything about Unix kernels: development, configuration, compilation, design, etc.

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Benefiting of sched_autogroup_enabled on the desktop

I am running a 2.6.37 kernel with sched_autogroup_enabled set to 1. I am not certain that I am seeing the benefits of this patch since: I am launching my applications from the desktop; applications ...
Robert Munteanu's user avatar
7 votes
1 answer
9k views

cat: /dev/ttyS0: Input/output error

I am unable to write to or read from /dev/ttyS0 # cat /dev/ttyS0 cat: /dev/ttyS0: Input/output error the device exists, and root has permissions. # ls -lAhF /dev/ttyS0 crw------- 1 ...
Martin Vegter's user avatar
6 votes
0 answers
613 views

Opening /proc/<pid>/net/dev prevents network namespace from expiring, is this expected?

I'm looking for input whether the following observation related to network namespace expiration is expected, or should be reported as bug? When some process opens /proc/<pid>/net/dev it can ...
Arne Welzel's user avatar
6 votes
2 answers
2k views

radeon errors: GPU lockup: ring 0 stalled for more than x msec

I have newly installed machine with Debian Buster. The GPU is radeon FirePro W2100. After couple of hours of use, the machine suddenly freezes, the display switches to "white noise", and machine is ...
Martin Vegter's user avatar
6 votes
0 answers
169 views

Kernel config for keyboard special LEDs

I'm building a 4.9 linux kernel (which is working great) for my T460s. The F1 key has a led that shows if sound is muted. I can't get this LED to work even when enabling all kinds of LED-relevant ...
Jan's user avatar
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6 votes
1 answer
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How to compile a third party driver into the kernel?

I am using Linux Mint 17.2 on Toshiba c640. As my LAN driver is no more functional, I am using a USB to LAN converter which was provided with some driver installation files. Every time i want to use ...
Maddyrdm's user avatar
6 votes
0 answers
2k views

Understanding Broadcom setup and kernel files

I often install Linux distros form live usb/CDs. For that I would like to be able to setup my wireless without any internet connexion. I have a Broadcom chipset : $ lspci -k 04:00.0 Network ...
kaligne's user avatar
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6 votes
1 answer
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What does "make install" do in the Makefile that comes with the kernel?

I'm trying to identify what does make install do with the kernel and what does the actual "install" of the kernel once it's been compiled means. The problem is I can't really identify the target (...
TheMeaningfulEngineer's user avatar
5 votes
0 answers
4k views

Kernel compiling - Error during sync of the configuration

I am trying to compile the 4.19 kernel on my Linux Mint machine. I copied my current config (which is from 4.15), opened make menuconfig in order to append a local version string, saved it and then ...
Raven's user avatar
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5 votes
1 answer
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Firmware Bug: disabling VPD access (can't determine size of non-standard VPD format)

I am using kali 2018.2 I am getting the error in dmesg : [ 0.388371] pci 0000:04:00.0: [Firmware Bug]: disabling VPD access (can't determine size of non-standard VPD format) Earlier I was getting ...
Akki's user avatar
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2 answers
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Kernel parameters are not changed permanently for RHEL7

Trying to permanently change some vm kernel parameters, I created /etc/sysctl.d/01-custom.conf config file as it described in Red Hat knowledgebase article. Here is its content: # cat /etc/sysctl.d/...
sys463's user avatar
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5 votes
1 answer
744 views

Kswapd using >90% CPU. What is it doing?

I have run GNU/Linux since 0.99, and it is only in the most recent years that I have seen kswapd use any serious CPU-time. In ye olde days the swapsystem would be waiting for the disk and hardly use ...
Ole Tange's user avatar
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5 votes
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433 views

Grub.conf vs sysctl.conf

Both files are being used to pass parameters to the kernel. so what exacly is the difference between the two? What is the purpose of each file?
Liron Cohen's user avatar
5 votes
0 answers
1k views

How to interpret perf -e cache-misses:pp?

I find the behavior of perf top -e cache-misses:pp -p <my_pid> quite confusing. I own an Intel i5-3230M, running kernel 4.4.5 64 bit. If I just run that commmand, I get basically no samples ...
Lorenzo Pistone's user avatar
5 votes
4 answers
6k views

How do I know if the kernel is changed?

I have a scenario where I need to recompile my display drivers after kernel updates. I'm trying to automate it with Bash scripts during boot time. So I need a way to know that my kernel changed, and ...
Asaf Magen's user avatar
5 votes
0 answers
2k views

Xorg on skylake graphics hangs

I've bought msi gs40 that has intel i7 6700HQ which means integrated graphics hd 530. After a day of struggling I was able to start xorg with HD530. For this I addes i915 to initramfs and i915....
deathangel908's user avatar
5 votes
0 answers
2k views

How do I configure a systemd service to execute simple /bin/echo "Hello world" command to show the output on the console?

I am trying to boot up a vm with qemu-system-ppc64(similar to lkvm). I am using the following command: qemu-system-ppc64 --enable-kvm -vga none -nographic -nodefaults -chardev stdio,id=id1 -device ...
Abhishek Dasgupta's user avatar
5 votes
0 answers
962 views

Are multiple signals given to a process served sequentially or their signal handler can cascade?

I was developing my own signal handling mechanism in User space. when browsing the kernel code and executing some c-code. I realized, Scenario 1 : When my code is executing a signal handler on ...
PSB's user avatar
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5 votes
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How to figure out why Linux crashes

Every so often, my laptop will crash. The screen will freeze, including the cursor, the lock lights (caps lock and the like) will turn off if they were on, though my battery, power, and wifi lights ...
RoboticRenaissance's user avatar
5 votes
0 answers
474 views

Is there something like "make localmodconfig" that detects *all* your hardware?

I understand that Linux's "localmodconfig" target looks through all your loaded kernel modules and produces a .config file that enables those modules. This is nice, but what about hardware whose ...
Theodore Sternberg's user avatar
5 votes
0 answers
3k views

is THP good or bad for MySQL Server?

Linux kernel new feature called Transparent Huge Pages (THP) which is by default enabled on CentOS 6.x and above OS. Is THP good for MySQL DB machine? I am trying following to disabled THP but seems ...
Satish's user avatar
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5 votes
1 answer
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Is it safe to disable Frequency Scaling and CPU idle Power Management support for Real Time purposes?

I'm using a Raspberry Pi board and I would like to build a real time system. During the kernel configuration, I found the CONFIG_CPU_FREQ option, which (from the help section) allows you to change ...
UserK's user avatar
  • 2,414
5 votes
1 answer
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Scaling issues of i7 3520M with intel_pstate module on Kernel 3.10.0

Few days ago I updated my openSUSE 12.3 system from Kernel 3.9.8-1.gf3348a8-desktop to 3.10.0-1.g3dcd746-desktop and since then, turbo mode of my i7 3520M is enabled by default and it does not ...
Torbjörn's user avatar
  • 308
5 votes
3 answers
2k views

How to install a bcachefs supporting kernel on Linux Mint 21.x and LMDE6?

2023-10-31, Bcachefs Merged Into The Linux 6.7 Kernel: https://www.phoronix.com/news/Bcachefs-Merged-Linux-6.7 https://web.archive.org/web/20231103095158/https://www.phoronix.com/news/Bcachefs-Merged-...
Alfred.37's user avatar
  • 164
4 votes
1 answer
132 views

Suspend doesn't work in Debian / powers up after a second

I already asked in #debian-next and on the forum, but thought I'll also ask here before switching back to Fedora. Suspend does not work. When I use systemctl suspend, the workstation goes into suspend ...
J. Doe's user avatar
  • 105
4 votes
0 answers
649 views

/proc/diskstats disk time spent writing more than 1000ms*CPU-core-count per second

I'm interested in how could one interpret the results of procfs-diskstats. It looks like an API, but I see no exhaustive explanation in Internet or man pages or Linux kernel Documentation. There is a ...
z0lupka's user avatar
  • 275
4 votes
0 answers
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xhci restart needed

I have a laptop with usb 3.0 ports, ryzen processor, linux 5.14.3 kernel, and an external keyboard and mouse connected via a usb hub. Occassionally, the usb devices stop functioning, both keyboard and ...
possumkeys's user avatar
4 votes
0 answers
423 views

CPU time accounting: report cumulative total CPU time

There are about 15 users on a computation server running jobs via SSH, Jupyter, or the web version of RStudio. Every user has a standard Linux user account, each process is owned by the user also if ...
lumbric's user avatar
  • 389
4 votes
1 answer
956 views

Trying to run linux kernel using QEMU, having trouble with boot process

For a project, I need to be able to run an uncompressed linux kernel. It was recommended to me to try emulating this using QEMU, since that's less involved than booting it straight on the machine. ...
user3705142's user avatar
4 votes
0 answers
1k views

Location of the system-wide file table and inode table structures in the kernel source

To better understanding of the file management in Linux kernel I want to find out three table declarations in the source: a single process file descriptor table system-wide table of open files inode ...
MiniMax's user avatar
  • 4,093
4 votes
0 answers
1k views

QEMU kernel for raspberry pi 3 with networking and virtio support

I used the QEMU(qemu-system-aarch64 -M raspi3) for emulating the Raspberry pi3 with the kernel from the working image. Everything was working but there was no networking. qemu-system-aarch64 \ -...
zeropoint's user avatar
4 votes
0 answers
359 views

Is it safe to enable Direct I/O for a loop device backed by a sparse file?

I'd like to have a sparse file, and mount it as a filesystem. It'd be great if the performance overhead is negligible, but only if that doesn't come with a data-loss risk! Is it safe to mount the ...
semekh's user avatar
  • 141
4 votes
0 answers
1k views

Do I need linux-update-symlinks to update /vmlinuz after installing a custom kernel?

Following the instruction I built and installed a custom kernel (and I will keep the old kernel as well) # apt-get install linux-source-4.19 $ tar xaf /usr/src/linux-source-4.19.tar.xz $ cd linux-...
rnd_nr_gen's user avatar
4 votes
0 answers
1k views

Looking at the kernel logs to see if there is something wrong with my machine

My ubuntu machine slowed down, I was following these instructions: https://askubuntu.com/questions/21632/slow-response-and-system-lag the slowness I see is pretty uniform, and there's definitely a ...
Alexander Mills's user avatar
4 votes
0 answers
268 views

Setting vm.dirty_ratio per cgroup

I was wondering if there is a way to set vm.dirty_ratio per cgroup? I see that the cgroup2 documentation mentions writeback but it seems that it will only use limits imposed by the memory controller ...
Srđan Miljević's user avatar
4 votes
0 answers
2k views

Core file may or may not escape docker container, depending on the core pattern

I am a docker noob who recently ran into a problem. I quote a random pipermail from years ago that poses the question far more elegantly than I ever could: I noticed the following core_pattern ...
AntsySysHack's user avatar
4 votes
1 answer
424 views

Kernel Panic not showing up?

I'm writing a kernel module and I was hoping to get the beautiful Kernel Panic screen with all the details when I call panic(), but my machine just freezes without displaying anything. I know kpanic ...
CAGYL's user avatar
  • 41
4 votes
1 answer
482 views

How to load additional modules when Xen hypervisor is loaded?

I'm currently running Debian 10 with Xen 4.12 installed. I compiled Xen from source on another machine with the below steps: ./configure --target=x86_64 --with-platform=efi --enable-systemd make ...
snow's user avatar
  • 41
4 votes
0 answers
5k views

Why is journalctl reporting "PCIe Bus Error" BadTLP and BadDLLP?

I am running Fedora 30 64-bit on an AMD Ryzen 2700U and I've noticed that journalctl gets a lot of messages about PCI bus errors (all identical). What might be causing this and what does it mean by ...
Zhro's user avatar
  • 2,649
4 votes
0 answers
82 views

Why doesn't disk io occur to read file system metadata despite clearing dentry and inode with drop_cache command?

As the title says, I am confused about "echo # > /proc/sys/vm/drop_caches" and blockdev --flushbufs. http://pages.cs.wisc.edu/~remzi/OSTEP/file-implementation.pdf According to OSSTEP, If the ...
PassionDG's user avatar
4 votes
0 answers
896 views

Debian Installer With Backported Kernel

I need to install Debian Jessie on a new machine, however I need the backported linux-image-amd64 and firmware-iwlwifi packages from jessie-backports in the installer to support my hardware. I was ...
ellioseven's user avatar
4 votes
0 answers
11k views

Linux kernel boot: uninitialized urandom read (16 bytes read)

In dmesg, I see the following entries: [ 0.989416] random: systemd-tmpfile: uninitialized urandom read (16 bytes read) [ 0.989708] random: systemd-tmpfile: uninitialized urandom read (16 bytes ...
Tom Hale's user avatar
  • 30.1k
4 votes
0 answers
885 views

Possible slab memory leak related to bio and btrfs?

I'm currently running a rebuild on a btrfs NAS (~20TB) that had a drive failure. It's going to take a few days. My problem is about once every 24 hours the RAM filled up and the kernel starts killing ...
HittingSmoke's user avatar
4 votes
0 answers
1k views

How to support 64-bit times on a 32-bit Linux platform

I need to support 64-bit times on a 32-bit ARM embedded Linux system based on kernel version 4.1. I use clock_gettime() and clock_settime() to get/set the time, but they are limited to 32-bit seconds ...
user5071535's user avatar
4 votes
2 answers
7k views

How to dump the dmesg AKA Kernel logs to a single .txt file from the kernel boot?

I am trying to understand the SATA Host-Device Communication and for that I have put a lot of debug messages in the kernel driver code. Now messages are in such a huge amount that I am not able to see ...
Hemant's user avatar
  • 113
4 votes
1 answer
527 views

Loading WiFi driver results in the whole system becoming unstable. How to debug?

I am not a linux kernel expert, but I got this new laptop and it's WiFi(RT3290LE) is not working. I tried solutions from various sources and they are not working. So it is upto me to solve it, and I ...
daltonfury42's user avatar
4 votes
0 answers
689 views

ABRT report says "irq 19: nobody cared", but why?

Every couple weeks, I need to reboot my system. When I do, and enter as root in the terminal, the following message (in some variation) appears: ABRT has detected 3 problem(s). For more info run: ...
user avatar
4 votes
0 answers
2k views

Centos 7 boot up with custom kernel problem

I have installed centos 7 on virtualbox machine which has kernel-3.10.0-123.20.1.el7.x86_64. I am trying to build Linux kernel from kernel sources. I downloaded the kernel source files from: http://...
nyzsirt's user avatar
  • 41
4 votes
0 answers
2k views

update kernel without restart

Recently Linux got a new feature called Live Kernel Patching, which you means you don't have to restart your system to update kernel. Is there any other kernel which has this feature already or Linux ...
Alex Jones's user avatar
  • 6,353
4 votes
1 answer
1k views

Debugging info in linux kernel - how does it work?

I have found that I can compile linux kernel with some flags adding debugging support like CONFIG_DEBUG_INFO. These options while useful in debugging are also required by some utilities like SystemTap....
KaP's user avatar
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