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

learn more… | top users | synonyms

3
votes
1answer
118 views

Linux exit function

I am trying to understand linux syscalls mechanism. I am reading a book and it in the book it says that exit function look like that(with gdb): mov $0x0,%ebx mov $0x1,%eax 80 int $0x80 I understand ...
1
vote
1answer
2k views

kernel: “echo 0 > /proc/sys/kernel/hung_task_timeout_secs”

I got this errors in syslog. Any idea what does it mean? The system is running on Ubuntu 12.04, kernel: 3.8.0-35-generic #52~precise1 It looks to me like failure when trying to write to disk... ...
2
votes
2answers
615 views

[FreeBSD] rc.conf, loader.conf vs static kernel linking

I'm curious: What, exactly are the benefits to statically linking modules into the kernel rather than loading through rc.conf, etc? For example: To add linux emulation, I could add ...
2
votes
1answer
28 views

Managing Pre-Built Kernel Modules Across Kernel Versions

Please read the full question before attempting to answer, this is a bit oddball of a situation. I support a lot of server hardware test functionality, and essentially end up managing several ...
2
votes
0answers
156 views

how to merge device tree overlays to a single .dtb at build time?

My board boots via U-Boot and AFAIK that bootloader does not support device tree overlays, so I'm probably forced to generate a single, static .dtb will all relevant overlays (and settings??) already ...
1
vote
0answers
11 views

Copy a driver to other kernel?

I have installed RemixOS on my Laptop (sony vaio SVF 1521V1EB) but the Wifi is not working... However I could make it working on Ubuntu, so my question that am I able to copy the module files from the ...
10
votes
3answers
12k views

How does the Linux kernel handle shared IRQs?

According to what I've read so far, "when the kernel receives an interrupt, all the registered handlers are invoked." I understand that the registered handlers for each IRQ can be viewed via ...
1
vote
1answer
243 views

cannot read key “net.ipv6.conf.all.stable_secret” in sysctl?

I am running kernel version as followings on an Arch Linux computer: [root@router ~ ]$ uname -a Linux router 4.2.5-1-ARCH #1 SMP PREEMPT Tue Oct 27 08:13:28 CET 2015 and I noticed that every time ...
27
votes
4answers
35k views

How to cause kernel panic with a single command?

Is it possible to cause a kernel panic with a single command line? What would be the most straightforward such command for a sudoing user and what would it be for a regular user, if any? Scenarios ...
1
vote
1answer
44 views

Q: How to tell the Linux Kernel to ignore MULTIPLE ata devices?

So, there were already questions about ignoring ata devices (like How to tell Linux Kernel > 3.0 to completely ignore a failing disk?) from where I got the info that one has to add something like ...
2
votes
1answer
59 views

Why does Linux have a maximum number of sound cards? [closed]

I'm specifically asking about CONFIG_SND_MAX_CARDS in the kernel. From the code using this config, for example in sound/usb/card.c for USB cards, soundcards are stored in plain arrays which are ...
0
votes
0answers
43 views

dd process real vs. sys time

I have two quad core workstations. One is based on Intel Atom x86_64 architecture (WS1). Another one is based on armv7l architecture (WS2). Both are running 3.10 kernel version. Identical busybox dd ...
3
votes
1answer
6k views

bnx2: Can't load firmware file “bnx2/bnx2-mips-09-6.2.1b.fw”

I just compiled the kernel 3.10.19 from kernel.org. Support for bnx2 is enabled. On my server when I try to start the eth0 interface I got the following error : bnx2: Can't load firmware file ...
0
votes
0answers
64 views

How do I support PTRACE_O_SUSPEND_SECCOMP and PR_SET_MM_MAP?

I'm trying to make Criu work. However, when I run sudo criu check, it gives me this error: prctl: PR_SET_MM_MAP is not supported, which is required for restoring user namespaces Error ...
13
votes
1answer
11k views

Buffer size for capturing packets in kernel space?

Going through the man page of tcpdump, it seems kernel can drop the packets if the buffer is full. I was wondering if: that size is configurable and/or where can I see the size for my distro? From ...
0
votes
0answers
10 views

How can I find the module responsible for interaction with keyboard [duplicate]

I have a laptop and want to be able to turn off keyboard for a while. I use this code: modprobe -r usbhid sleep 10 modprobe usbhid But as my keyboard is not usb, and it only blocks mouse. How can I ...
4
votes
1answer
99 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 ...
4
votes
1answer
560 views

What does this dd command do exactly?

I have an embedded device with this SD card: [root@(none) ~]# busybox fdisk -l Disk /dev/mmcblk0: 3965 MB, 3965190144 bytes 4 heads, 16 sectors/track, 121008 cylinders Units = cylinders of 64 * 512 = ...
5
votes
3answers
3k views

ACPI problem with recent kernels

In recent versions of popular Linux distributions (Ubuntu, Fedora, Mint, Debian) I always have to put acpi=off into the kernel parameter list before I want to boot the computer. This happens to both ...
2
votes
1answer
83 views

Can a bootable NetBSD be built on OSX?

I've got OSX 10.9.5 . I want to build NetBSD (or at least it's kernel) on my OSX box. I've tried building the 'config' program but I can't find 'build.sh'. Is this possible and what would be the steps ...
5
votes
1answer
1k views

Debugging Linux Kernel with QEMU

I was trying to study the debugging of kernel using QEMU. I tried initially and failed due to the fact that there was no virtual file system. The answers to this post suggests that there should be a ...
1
vote
4answers
237 views

Kernel panic after Gentoo install — cannot open root device

I have a Debian system on /dev/sda1 (/) and /dev/sda2 (extended, /dev/sda5 is /home, /dev/sda6 is swap). I want to install Gentoo in parallel, so I shrinked sda2 and created /dev/sda3, in which I ...
1
vote
1answer
719 views

“rcu_preempt detected stalls on CPUs / tasks” message appears to continue

My board continues to display the message below. The terminal does not have any input. What is it with the following message, which I know? (T, g, c, q ...) What is the cause of this phenomenon? ...
0
votes
2answers
88 views

In Debian Jessie, make allnoconfig and make allyesconfig generate the same .config file

In debian jessie, I've installed the linux source with: sudo apt-get install linux-source I obtain a file /usr/src/linux-source-3.16.tar.xz, I copy it under my home directory, change the ownership ...
1
vote
0answers
59 views

Shared IRQs not operating properly

I'm having problems trying to make use of four out of six serial ports on my motherboard. The situation is: I have 6 serial ports available - ttyS0 to ttyS5 - of which 0 is a RS232 port on the edge ...
3
votes
2answers
228 views

No /dev/mmcblk0 during boot

I am trying to install CentOS-6 on an eMMC drive. Since the supported 2.6.xx kernel from CentOS-6 doesn't support mmc, I compiled a newer kernel (4.2.6) which has updated mmc drivers. I tried booting ...
0
votes
1answer
41 views

What is the information present inside a kernel core dump

I am running CentOS 6. The system got a Kernel Panic and rebooted. I have enabled coredump generation, hence it generated a Kernel Core Dump of Size 300MB. What is the information that got ...
3
votes
1answer
50 views

FreeBSD: How can I install kernel sources for 10.2-STABLE version?

Lots of articles and posts on internet tell how to install the kernel sources for FreeBSD x-RELEASE versions, but none of them for X-STABLE. For example, my FreeBSD version is 10.2-STABLE. How can ...
0
votes
0answers
67 views

Arch linux kernel upgrade from repositories

About two months ago I build a kernel (4.2.6-ARCH) from source according to this page, this is my current kernel version, the problem comes when I try to upgrade from the repositories, actually I did ...
0
votes
0answers
150 views

CentOS update from 7.1 to 7.2 with 2.6 OpenVZ kernel?

We are using CentOS 7.1: $ cat /etc/redhat-release CentOS Linux release 7.1.1503 (Core) We deferred the 7.2 upgrade. It looks like it did not cause any problems so we are planning an upgrade. The ...
25
votes
8answers
11k views

How does Linux kernel compare to microkernel architectures?

I read once that one advantage of a microkernel architecture is that you can stop/start essential services like networking and filesystems, without needing to restart the whole system. But considering ...
0
votes
2answers
31 views

prevent from writing to a large continuous section of virtual memory [closed]

How can an operating system kernel efficiently prevent a user process from writing to a large continuous section of virtual memory?
8
votes
1answer
3k views

Which Debian kernel should I install?

I've started installing Debian testing on amd64 and I've come to a screen asking me to install a kernel. It gives me a choice between linux-image-3.16-2-amd64, linux-image-amd64, and none. What is ...
1
vote
0answers
28 views

Identifying disk drives during RHEL/CentOS/Fedora Installation

What steps are followed in order to identify a connected disk drive during Linux installation ? I am interested RHEL/CentOS/Fedora procedures. Is it entirely depends on the Kernel package and drivers ...
37
votes
5answers
21k views

What is the difference between kernel drivers and kernel modules?

When I do a lspci -k on my Kubuntu with a 3.2.0-29-generic kernel I can see something like this: 01:00.0 VGA compatible controller: NVIDIA Corporation G86 [Quadro NVS 290] (rev a1) Subsystem: ...
0
votes
0answers
83 views

Unable to setup TL-WN722N or Unable to install/complete headers

I would like to set up the tl-wn722b WLAN Adapter. I have a Kali Linux version for a Raspberry Pi. I tried to follow this tutorial: ...
0
votes
0answers
40 views

How does GUI works different from the shell CLI?

For example if I want to remove a file I would write rm command in my shell CLI. But when I delete a file using GUI how does the process works ? For shell it would find the filesystem for rm program ...
93
votes
4answers
62k views

How do I read from /proc/$pid/mem under Linux?

The Linux proc(5) man page tells me that /proc/$pid/mem “can be used to access the pages of a process's memory”. But a straightforward attempt to use it only gives me $ cat /proc/$$/mem ...
0
votes
2answers
99 views

Copy the Linux kernel config file to another distribution

I am installing new Linux distro (gentoo) and I want to copy the linux kernel config I have here in the linux mint live USB to the Gentoo system. The way Mint has the kernel config file is ...
3
votes
1answer
168 views

change size of devtmpfs /dev/

My new kernel has CONFIG_DEVTMPFS enabled, and thus my /dev is mounted as devtmpfs. My old kernel was not using CONFIG_DEVTMPFS, and /dev used to be mounted as plain tmpfs. Now I have noticed, the ...
0
votes
0answers
40 views

Problem with xv6 on qemu

I was doing the assignment on this link --> http://zoo.cs.yale.edu/classes/cs422/2013/lec/l2-hw After running make qemu the assignment document says A separate window should appear ...
4
votes
1answer
107 views

Different Debian versions from two different commands

This might be silly, but I'm new to Linux. I wanted to check my current Debian version so I typed uname -a and it gave me some stuff including Debian 3.2.73. But Then I found this command cat ...
1
vote
0answers
172 views

Error while building Linux kernel for versatile board

I'm trying to build the 2.6.32.69 version of Linux Kernel for versatile board but I got this error during the build step init/mounts.o: In function `tty_port_users': ...
1
vote
1answer
1k views

How can Linux 4.2.5 boot on a Skylake CPU when they are supported from 4.3+

I bought a Dell XPS 13 2016 with a i7-6500u (SkyLake). This notebook is not officially linux-supported but I found a few articles on how to get it up and running. But I cannot find an answer to this ...
1
vote
1answer
96 views

DKMS modules never installed properly on kernel upgrade

I have multiple DKMS modules installed on my system, some of them mine, and some of them belonging to pretty major maintained packages such as Oracle's VirtualBox 5. What I've found is that on every ...
2
votes
1answer
848 views

TUN/TAP Will not load

I have an OpenVZ server but can't seem to get the tun/tap module to load. I ran modprode tun on the hostnode but when I go under the VM I get: Tue Sep 24 03:08:36 2013 Note: Cannot open TUN/TAP dev ...
2
votes
1answer
79 views

Change the parameters a kernel module loads with

When I plug in an SD card in Ubuntu, the module mmc_block loads with the value of mmcblk.perdev_minors set to 8. I am pretty sure this is the default value coded into the module. What file might I ...
4
votes
1answer
191 views

How the terminal can run programs and show its output? [closed]

I'm slowly creating a mental model of how linux works, and I've tried to simplify the most, my model of how linux works. Let's assume that the kernel boots and inits the only software it's gonna run: ...
2
votes
0answers
799 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 ...
1
vote
0answers
35 views

My SLES 11 uses 6 GB RAM while nothing is running. How can I find out what is needing it? [closed]

Can anybody tell me what is consuming that much memory on my SLES 11 SP3 server? I suspect a serious bug in the kernel that it does not release memory allocated by an application once it quits. This ...