Questions tagged [kernel]

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

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kernel headers installed but still missing

I'm working on a RPI2B+ with a fresh install of Raspbian Buster I want to install https://github.com/Mange/rtl8192eu-linux-driver.git so I have to run the following commands : apt update apt ...
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install centos older kernel version

Currently I'm using Kernel version 3.10.0-1062.el7.x86_64 and I want to downgrade to 3.10.0-957.27.2.el7.x86_64 (that was not installed, it needed to support existing project) I've tried: yum ...
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Install own kernel in CentOS. Is that possible?

So I'm having a customized kernel(.deb packages). And like I wanna apply kernel on CentOS. Is this possible? Over the internet found out that it's possible with "dracut tool", but how? Or I ...
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Unable to load the 'nvidia-drm' kernel module

I'm trying to install nvidia drivers on my Manjaro linux. But .run file tells me "ERROR: Unable to load the 'nvidia-drm' kernel module." What should i do?
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How does the Linux kernel initialize the mem_map array on 64 bit systems?

I know that the Linux kernel keeps track of the status of each physical page frame with the help of a C structure struct page. The structures for all page frames form an array mem_map[]of type struct ...
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Is it possible to execute a function in a kernel module after init and before exit?

In a kernel module I have an init function which is executed when the kernel module is loaded and an exit function which is executed when the module is unloaded. I want to have a loop run for a long ...
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Kernel upgrade - apt autoremove before the reboot or after it?

When you upgrade the kernel, especially if you have relatively small /boot partition, it is necessary to run apt autoremove to free space. Is it safe to execute it before rebooting?
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How to instant shutdown or halt in linux, without wait the system or apps or process close?

I'm working in a custom linux distro, that automatically saves any file or write the hard drive to prevent losing data, Ok i need to shutdown the computer without wait close apps or close system, ...
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Fedora 30 randomly fails to boot: “unexpected kernel core error”

I'm having this problem with my Fedora 30 Linux system which I mainly use for machine learning and software development. Usually, the computer works with no signals of hardware faults but sometimes ...
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Would an asynchronous interrupt context write to the page table in the Linux kernel?

Specifically, in the Linux kernel, is it possible that the page table (level3_kernel_pgt) can be overwritten when an asynchronous interrupt context happens (Local timer interrupts). I've been seeing ...
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No display on different kernel

I got installed two kernels: 5.0.0-37 and 5.3.0-24. The first one runs smooth in my office - where I have three monitors and all of them are working, but when I boot it with no monitors connected - ...
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kallsyms initializing process, how s_start works? [migrated]

I am trying to figure out how the kallsyms initializing works. from kallsyms.c I found this struct static const struct seq_operations kallsyms_op = { .start = s_start, .next = s_next, ....
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How to intercept any call to the kernel to spawn a process

I am attempting to make a program that is a system security watchdog. Any processes or ports that are not supposed to be open will be closed by the watchdog to mitigate a breech in security. I'm ...
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Arch Giving me a Black Screen with fixed white underscore after update

Almost certain it's something to do with discrete/integrated Nvidia and Intel GPUs. Ran pacman -Syu last night, went to turn on my laptop this morning and it wouldn't boot. Turning off quiet in grub ...
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How to figure out cause of high kernel/kworker CPU usage?

Sometimes the kernel uses up 40-50% of my CPU, causing lag in other programs. At the times this happens, the output of iotop looks like this: Total DISK READ : 2.96 K/s | Total DISK WRITE : ...
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How can a small MTU cause a Linux kernel crash?

man 7 netdevice states: SIOCGIFMTU, SIOCSIFMTU Get or set the MTU (Maximum Transfer Unit) of a device using ifr_mtu. Setting the MTU is a privileged operation. Setting the MTU to too small ...
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How can we get ACK frame in user space application in wireless(cfg80211, mac80211, mt7601u driver) Linux?

I am using mt7601u as WiFi driver in one of embedded board with Linux kernel supporting wireless feature. I am able to send management frames(action frames) from user space applications(iw) from first ...
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Sign Kernel Modules

So i am on a debian buster 10 system and i installed virtualbox and i encountered an error which tells me to load some kernel modules manually. sudo ./vboxconfig [sudo] password for raitack: ...
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After deleting Ubuntu in a dual Windows 10 and Ubuntu, now none of the two boots up

grub> ls (hd0,1)/ System Volume Information/ Ubuntu-18.04.3-desktop-amd64.iso But Ubuntu does not boot and neither does Windows 10. I get an error message: You need to load the kernel first ...
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Is there a way to mount a bluetooth device as a bluetooth USB device?

I run Qubes, which is based on Xen. I have a virtual machine called sys-usb just for handling USB. This machine makes available all the USB devices and I can redirect them to other VMs. This VM has ...
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Unable to disable kernel module

I'm trying to disable kernel module for my motherboard's bluetooth chip: btintel. I've added a blacklist entry to /etc/modprobe.d/blacklist-btintel.conf (I also tried blacklist.conf, this didn't make ...
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Why do I have two kernel on my boot manager?

After my PC runs I can see three options which are Fedora (5.3.16-300. fc31.x86_64) 31 Fedora (5.3.7-301. fc31.x86_64) 31 Fedora (0-rescu-bd .....) 31 Windows 7 Searching on the Net, I found that "...
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Will Upgrading Debian Kernel Change output of lsb_release?

I started with a Debian Jessie distribution and have upgraded it from a 3.X kernel to 4.19 now. There are still things that are not fully working (broken packages etc). As I am going through cleanup I ...
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Download suse kernel

I'm looking for a way to download every new kernel released or kernel-devel package for suse enterprise. I found this source: openSUSE download server but It seems not compatible with enterprise ...
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How to find acpi drivers for specific acpi device / Solving kernel suspend bug

I'm following https://wiki.ubuntu.com/DebuggingKernelSuspend and it says that I have to reboot the system with sudo sh -c "sync && echo 1 > /sys/power/pm_trace && pm-suspend" and ...
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Android memory manipulating

As root user when i try to modify my own application memory with ptrace and /proc/$pid/maps and /$pid/mem everything is going well, But when i try to attach ptrace to process of another application ...
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What is the difference between initial_apicid and apicid in cpuinfo_x86 struct?

I didn't find in any place what is the difference between initial_apicid and apicid in cpuinfo_x86 struct. I just saw that in case x2apic is not enable those fields may not contain the same value but ...
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How to profile the execution times of kernel functions in custom kernel module with system tap?

I have written below systemtap script, profiler stores the average time of execution of each kernel function starting with mx_, and counter stores the frequency of a function call. global start, ...
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Error while trying to compile kernel module

I am following an online tutorial on how to enable VMX operations on x86 architecture. The tutorial has broken the procedure into steps and has posted the code assembled from all the parts into a ...
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How to switch 5v USB on/off?

I purchased a HMI(Human-Machine Interface -Exor Esmart04) running on Linux with kernel version 3.10.12. On this HMI there is a USB port which outputs 5V, this 5V I'm trying to switch on/off using a C ...
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Are there custom memory manager (mm) replacements for Linux kernel?

Are there alternatives to Linux kernel memory manager (mm)? More specifically, are there companies that develop their own replacements for mm algorithms to suit specific needs such as supercomputing ...
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What are masked during execution of interrupt in linux kernel [closed]

When an interrupt handler is executing in Linux Kernel for a particular interrupt, whether all the interrupts are masked/disabled or that particular line which is served by CPU is masked/disabled. ...
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Why can't entire kernels be patched live?

Over the past few years, various live kernel patching techniques have become popular among sysadmins who strive to ensure the highest possible uptimes for their systems. For that process to be ...
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Finding reason for reboot RHEL 7

I have RHEL 7 machine running workloads. The machine is provisioned in AWS of instance c5. During workload the process got killed and the machine shutdowns. I need to analysed why the machine got ...
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1answer
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How does kbuild compare to the device tree?

I know KConfig serves to tune the C preprocessor, at the start of the Linux kernel compilation. And that the device tree is used to give a compiled kernel a description about hardware at runtime. How ...
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at what stage in the boot process, does kernel load the firmware files?

I have AMD radeon gpu which needs to load many firmware files. My system boots from initrd (initial ram disk), and I am now confused at what stage in the boot process, the firmware files need to be ...
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How to get the kernel version of the next boot from a script

I need to find out which kernel will be used for the next boot, regardless of current running kernel, and this is done in a shell script. There could be multiple kernels installed, GRUB is configured ...
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97 views

How/Shall I keep libc and kernel in sync?

If I compile latest kernel from kernel.org, make a deb package and install it on my Debian system, shall I worry about libc (and any other libraries?) and kernel being out-of-sync? I vaguely ...
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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 ...
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Manjaro update-grub syntax error

After letting my computer sit for an extended time without updating, I ran Pacman -Syu for a full system update. During the update the process was interrupted or something because the grub entries ...
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Open Network Linux (ONL): kernel source patch

I'm trying to apply some patches on the ONL kernel. Based on a question and its reply, there is a method to apply patches. (The link: https://groups.google.com/forum/#!topic/opennetworklinux/...
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Invalid Vdd is coming during mmc driver access

I am getting invalid vdd while mmc driver access in linux boot up. basically during mmc_power_up function, after executing __mmc_set_signal_voltage and before setting power mode to MMC_POWER_ON, ...
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What happens when kernel gets ahold of a userspace pointer? [closed]

If the kernel makes use of a userspace pointer as if it was a regular pointer, the kernel could: return confidential kernel data to a process overwrite kernel data it shouldn't attempt to write to ...
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23 views

Preprocess the Linux source code and save to another directory

Suppose I have the entire Linux source code in /tmp/linux-src. After menuconfig I want to do "some kind of gcc -E" where all the preprocessor macros other than #include are expanded so the actual ...
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Reliably automatically detect OOM killer post-mortem

I have a misbehaving service which is being repeatedly OOM killed which I would like to better diagnose. It's being called by a wrapper script, so the best first step I can think of is to have the ...
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How to read what a process is sending to /dev/net/tun?

I altered OpenVPN's client source code to send IP packets through my app, not through the operating system. Therefore I'm creating the IP packets by hand (using libtins). I can see that they arrive ...
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How are socket typed files(S_IFSOCK) used in Linux ext4 filesystem?

In kernel 5.4 code, special inode for device files and FIFOs is hooked to their special f_ops, but sockets are left dangling. void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev) { ...
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Can't access RAM from PCIe device

I use Intel Xeon with centos8 , kernel 4.18. There is also an FPGA connected to CPU through PCIe. The FPGA try to access RAM (through DMA) using physical address in RAM, but it fails in access. ...
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43 views

Can't disable swap on a GPT-based system

I want to disable swap on several running ubuntu 16.04 servers. I'd like, if possible, not to reboot them. From my research, it seemed that running swapoff -a to disable swap until the next reboot ...
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performance monitoring of “iptables” kernel module

I would like to know how much CPU / memory my current iptables rules consume? I have tried looking in ps and htop, but even with kernel threads displayed and did not see anything related to iptables. ...