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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.

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Linux kernel not cross-compiling - how to disable cc1 -quiet flag?

I'm trying to compile the Linux kernel, version 4.12.0, for ARM. I've used a toolchain from toolchains.bootlin.com, and they test all their toolchains by doing exactly what i'm trying to do, but when ...
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1answer
17 views

Memory immediately available in linux memory management system

This is the output of free -h command on my Ubuntu 18.04 laptop: $ free -hg total used free shared buff/cache available Mem: 11G 4,2G 3,4G ...
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What options for the implementation of the insmod on the Linux kernel configuration?

I'm learning to try to make minimal Linux following the tutorial, I tried load a module but I get an error like this: / $ insmod kdb.ko insmod: can't insert 'kdb.ko': Function not implemented / $ I ...
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0answers
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How do I upstream a patch into the Linux kernel developed by someone else?

I've recently been trying to upstream part of the Nintendo Switch-on-Linux patchset, but it appears that the original developer must sign off on each commit. Do I need to ask the original developers ...
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3answers
48 views

Kernel cannot find init in initramfs image

I'm trying to get my embedded system to run an initramfs. Right now 'init' in this initramfs does nothing but echo a message to test if it is being ran. My init script: #!/bin/sh echo "HELLO ...
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1answer
32 views

kernel sysfs doesn't recognize storage kobjects [on hold]

I am using ubuntu kernel 4.xx with corresponding ubuntu initrd.img, and it works. But, I want to use a custom initramfs inspired by lfs (linux from scratch) initramfs. The kernel extracts, and runs ...
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2answers
59 views

Archlinux failed to boot: can't access tty: job control turned off

I came across the problem after upgrading my system through pacman -Syu. During the upgrade, I encountered a python package conflict which caused the upgrade transaction aborted. So I resolved the ...
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0answers
15 views

How can I add parameters to the Linux Kernel scheduler? [migrated]

I am learning to work wiht Linux kernel. Currently I am using 4.15.0-36-generic. I understood that the schedulers after the kernel 2.6 use a completely fair scheduler. I also came to know that, the ...
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2answers
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In /proc/meminfo, does Dirty include or exclude Writeback?

Dirty %lu - Memory which is waiting to get written back to the disk. Writeback %lu - Memory which is actively being written back to the disk. -- man proc Does Dirty include Writeback? Or ...
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1answer
26 views

Which logs to look when kernel reboots because of panic?

I wish to set kernel.panic=1 and kernel.panic_on_oops=1. Is there any log I can check before/after reboot, which will indicate that the reboot was because of a kernel panic?
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1answer
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kernel: BUG: soft lockup _raw_spin_unlock_irqrestore

System reboot after hung, the soft lockup message keeps come out. since the vmcore not enable before reboot, no vmcore. kernel: 3.10.0-327.el7.x86_64. If someone has the similar problems before, do ...
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0answers
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What is xen_hypercall_sched_op?

Out of curiosity, I ran perf top on a (mostly idle) virtual private server to see what I would get. The resulting table had [k] xen_hypercall_sched_op at the top, with 90+% overhead. What is this, ...
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1answer
31 views

Running make -j$(nproc) or make modules -j$(nproc)

I am following this. To run make -j$(nproc) make modules -j$(nproc) I know that make is running jobs Are the jobs supposed to run for hours? (I got impatient and interrupted.) make -j$(nproc)
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1answer
40 views

Re-add ncpfs module to linux kernel 4.18, with Debian

I'm using Debian "testing". At my work we have a Novell network and we are "forced" to use ncpfs. With kernel 4.18 this module/driver was removed from kernel. Can someone explain how to re-add this ...
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1answer
19 views

Arch AMDGPU-PRO hw_init failed -110 [closed]

So I have arch running on a mining rig and everything was running fine until I tried adding a 5th GPU. On boot I get an error that says hw_init of IP block failed -110. I've switched around risers ...
1
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1answer
56 views

Writeback cache (`dirty`) seems to be limited to even less than dirty_background_ratio. What is it being limited by? How is this limit calculated?

I have been testing Linux 4.18.16-200.fc28.x86_64. My system has 7.7G total RAM, according to free -h. I have default values for the vm.dirty* sysctl's. dirty_background_ratio is 10, and ...
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1answer
32 views

How do I check the kernel version of a specific Linux distro version (not installed)?

For example, I would like to know the kernel version CentOS 7.4 1708 uses. What is the easiest way to do it? Do I need to dig official website or there is a more easy way like a database or ...
2
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2answers
45 views

Cannot install Debian Stretch kernel headers

I am running Debian 9 Stretch on a VPS & dedicated server. I have updated both to the latest kernel on the backports repos with apt install linux-image-4.18.0-0.bpo.1-amd64 The problem is when I ...
2
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1answer
35 views

AMD Ryzen 2600 temperature [closed]

I have installed it87 module and here is my sensors output asus-isa-0000 Adapter: ISA adapter cpu_fan: 0 RPM it8665-isa-0290 Adapter: ISA adapter in0: +0.65 V (min = +1.12 V, max = ...
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0answers
8 views

Custom Kernel Qemu: No Choice for rootfs

I tried creating a custom kernel config, but can't boot now. The qemu command looks like the following: qemu-system-x86_64 -kernel $KERNEL/arch/x86/boot/bzImage \ -append "console=ttyS0 ...
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1answer
41 views

Critical boot error [closed]

While I was cleaning up my pc, I accidentally uninstalled a package I shouldn't have uninstalled (can't really remember what I uninstalled thought ). As a consequence, a total of 599 packages were ...
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2answers
74 views

How does linux know where the rootfs is?

I'm trying to understand how the linux kernel knows where the desired rootfs is on boot. I read this document: https://www.kernel.org/doc/Documentation/filesystems/ramfs-rootfs-initramfs.txt One ...
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1answer
18 views

Can QEMU -M virt on arm / aarch64 have multiple serial TTYs like such as PL011 ttyAMA0 and ttyAMA1?

I was playing around with TTYs, and for qemu-system-x86_64 -M pc, whenever I pass the -serial option it crates a new TTY and I can attach a serial like ttyS0 and ttyS1 to it from Linux. For ARM ...
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0answers
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2 Questions about memory check pointing with linux kernel (custom implementation) [migrated]

We are given a project where we implementing memory checkpointing (basic is just looking over pages and dumping data found to a file (also check info about the page (private, locked, etc)) and ...
2
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1answer
156 views

How do you debug inability to delete a Namespace after ip netns add test [closed]

cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer) cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct) cgroup on /sys/fs/...
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2answers
45 views

What are file-level snapshots , is there any file system that supports this feature?

I am trying to understand what are file level snapshosts. Anyone has idea as to which filesystems supports this so that I can try it out. Ref. http://tracker.ceph.com/issues/24464
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0answers
17 views

How do I merge a single feature of the Linux Kernel into my project?

I'm building a custom kernel for Android, but I want to replace Motorola's F2FS implementation with that of upstream Linux, which is unaffected by a certain bug present in the former. I dont know a ...
2
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0answers
14 views

Seperate Metadata Support [closed]

Adding some background to the question, to make it understandable: This is with respect to NVMe protocol - Along with an I/O command, if required, metadata too can be sent/received to/from the ...
1
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1answer
37 views

What do “ACard AHCI SATA low-level driver” meaning? What is “ACard”? [closed]

I run on Debian Stretch,my linux-kernel version is 4.14.13 Is this module never used(real loaded) in initramfs for desktop PC? The context is for initramfs and I have a very slow usb storage device(3....
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0answers
63 views

Unable to boot from kernel 4.18.16-200.fc28.x86_64

I updated the kernel last Thursday to version 4.18.16-200.fc28.x86_64. Now every time I booted from that kernel it just always get stuck on an empty black screen with blinking cursor. I've tried ...
2
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0answers
31 views

How does the Linux 3.10.105 kernel handle Ethernet broadcast storms?

In my embedded Linux device I want to find the source of Ethernet broadcast storm and flash the led once I detected the ethernet broadcast storm. Does Linux kernel handle broadcast storms? Is there ...
1
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0answers
48 views

Unable to boot a compiled kernel [closed]

I am working on a project where I have start of by adding some system calls to a kernel (Linux 3.13.11 to be particular), after adding the calls and writing their prototype in the correct locations ...
7
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1answer
215 views

What is the state of Linux kernel support for Intel Quiet System Technology (Intel QST)?

I am trying to find a way to access and/or control fan speed via Linux on an Intel Q45 Express/ICH10DO chipset. This chipset contains a feature called Intel Quiet System Technology (Intel QST), which ...
1
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1answer
35 views

What is cpu_entry_area?

The documentation of the Linux kernel describes the virtual memory map. It says: fffffe0000000000 - fffffe7fffffffff (=39 bits) cpu_entry_area mapping What is this "cpu entry area"? Is it ...
0
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1answer
39 views

Uninstall old kernel Fedora 28 Workstation

I have the below kernels installed on my machine: [rajiviyer@rajiv-pc dnf]$ sudo dnf list installed kernel Installed Packages kernel.x86_64 4.16.3-301.fc28 @...
1
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1answer
19 views

ACPI Errors: How, Why, and What's the Deal? [closed]

I've seen ACPI errors pop up on everything from Debian to Arch, and on multiple different devices. I'm aware of what ACPI is at a high level: ACPI (Advanced Configuration and Power Interface) is ...
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1answer
42 views

zscaler certificate issue

Do any one have idea what could be error reason and how it can be resolved? [root@Linux ~]$ wget https://www.google.com --2018-10-19 07:46:25-- https://www.google.com/ Resolving www.google.com... ...
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1answer
35 views

Processes PPID changed to 1 after closing parent shell

Opening a new terminal and typing the command firefox& inside, ps -l gives : 4 R 1000 23132 23104 99 80 0 - 2177945 - pts/27 00:00:07 firefox If the shell is closed with the command ...
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2answers
42 views

What ELF types do kernel itself and kernel modules have?

https://linux-audit.com/elf-binaries-on-linux-understanding-and-analysis/ says The type field tells us what the purpose of the file is. There are a few common file types. CORE (value 4) DYN (...
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1answer
64 views

How does Linux kernel dynamically use a module?

Understanding the Linux Kernel says The kernel has two key tasks to perform in managing modules. The first task is mak- ing sure the rest of the kernel can reach the module’s global symbols, such ...
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0answers
30 views

Linux Dual Boot Macbook Pro 15

I am looking to dual boot my MBP 15". I have read mixed opinions on this one webpage specifically says it won't work due to the Force touch trackpad. But on some reddit forums i have seen people say ...
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1answer
56 views

Does the Linux kernel have its own page table?

Different processes have different different page tables for their address spaces. Does the Linux kernel have its own page table? If not, how are the virtual addresses of kernel translated to ...
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0answers
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Suspending (to disk or ram) changes USB drive device file

When the system is suspended (to ram or disk), the USB drive (/dev/sdb) is "moved" to /dev/sdc. When it is mounted, it stops working. I have root on this device so I can't work with system. (I only ...
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0answers
42 views

chroot input/output error with custom ubuntu

Recently i tried making a custom ubuntu distibution and i came across a template for such with everything setup except the filesystem.squashfs in the casper folder, so i decided to extract another ...
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0answers
26 views

i2cdetect -l don't return anything [closed]

I need to use the SMBus, but when I run the command i2cdetect -l I do not receive anything as output, on Windows it was recognized, I do not see anything about SMBus even doing lspci. I installed and ...
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1answer
102 views

How exactly are NetworkManager, networkd, netplan, ifupdown2, and iproute2 interacting?

I am learning about Linux networking on my Kubuntu 18.04 workstation, and I see there that both NetworkManager and networkd-dispatcher are running: oleg@eclectic:~$ sudo ps -ef | grep -i net root ...
4
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1answer
137 views

lsmod 'used by' shows -1 while CONFIG_MODULE_UNLOAD=y

In this post there is some explanation about why does lsmod show -2 in 'used by' column. The idea is that the kernel config option CONFIG_MODULE_UNLOAD was not set. But what if lsmod shows -1 only ...
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2answers
48 views

Is Linux kernel parameters separated by space (0x20) or NUL (0x0)?

I thought it was NUL. But today when I wrote a script, I found that it was space. Is it configurable? Or just my memory wrong?
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1answer
44 views

What code prevents mount namespace loops? In a more complex case involving mount propagation

Background information The following commands return an error: # touch /tmp/a # mount --bind /proc/self/ns/mnt /tmp/a mount: /tmp/a: wrong fs type, bad option, bad superblock on /proc/self/ns/mnt, ...
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1answer
69 views

Force loading kernel module at startup

Some of my hardware needs the module cx23885. For some reason modprode cx23885 doesn't work, instead only modprobe cx23885 --force-modversion works. This hardware is currently somewhat buggy and ...