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

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Why would the kernel drop packets?

I interrupted tcpdump with Ctrl+C and got this total summary: 579204 packets captured 579346 packets received by filter 142 packets dropped by kernel What are the "packets dropped by kernel"? Why ...
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0answers
76 views

Output shutdown messages to multiple consoles

I have configured my system to direct console output on boot to serial and vga using kernel parameters. Serial is the last argument in the kernel parameters and will be the default used for ...
3
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1answer
54 views

Is there a man section or other doc repository for data structure definitions?

For the millionth time or so I had to look in /usr/include/foo.h to find the members of a struct foo or foo_t or whatever. There's a man section for library and kernel calls, some of which include ...
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0answers
73 views

SLES 10 SP4 - how to get specific kernel source?

I want to look at the kernel source for some specific kernel versions on SLES 10 SP4. I don't want to see just the Linux kernel source, but the one SLES is actually running. Suppose I wanted to get ...
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1answer
132 views

ncurses-devel problems in SuSE Linux Enterprise Desktop 11

Searching on the WEB, I found this tutorial (the only one that has convinced me) for installing a new kernel and I followed the steps provided. But, I got these problems: In the first step I tried ...
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4answers
172 views

Why does *BSD uses driver specific names for network interfaces? Does it imply limitations?

I notice that depending on the brand of the network card, interface names differ (driver dependent I suppose). Why does *BSD uses driver specific names for network interfaces? Does it mean there is ...
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0answers
68 views

Calling speaker-test from usermode-helper API

I needed to call come audio-producing applications from kernel in a toy module. In order to test that, I thought of calling speaker-test from a simpler module, but no sound would ever come from it. I ...
2
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3answers
69 views

Un-mount active partition

Is it possible to umount the partition, whose files/directories are in use? The underlying files and directories are in memory so un-mounting the partition is technically safe (I guess). But umount ...
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2answers
910 views

Configure timestamp format of kernel log?

Is there a way to change the format of timestamp in kernel logs? It was something like 2012-08-27T8:54:35.939421+03:00 now, I also checked sysctl -a | grep log, nothing found really.
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91 views

cross compile embedded arm

I have the android 4.2.2 code in directory /home/sghPhone2 which compiles normal with make menuconfig but I need to compile a 4.4 kernel and possibly patch it but when I download the source from ...
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3answers
81 views

Could it cause any problem if I not reboot after a kernel upgrade?

I know there are solution for not rebooting after kernel update: https://en.wikipedia.org/wiki/Ksplice But If Ksplice isn't installed, and the user doesn't reboots it's notebook after even several ...
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1answer
1k views

YUM won't update KERNEL

... ... ... --> Running transaction check ---> Package db4-devel.x86_64 0:4.7.25-18.el6_4 will be installed --> Processing Dependency: db4-cxx = 4.7.25-18.el6_4 for package: ...
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1answer
212 views

How not to write kernel warnings into /var/log/messages?

I keep getting these log warnings due to a bug in kvm. Jun 30 19:12:31 server kernel: kvm: 28882: cpu0 ignored rdmsr: 0x345 Jun 30 21:12:31 server kernel: kvm: 31191: cpu0 ignored rdmsr: 0x345 Jun ...
2
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3answers
222 views

Why is kernel boot starting too late

Log message from ARM Cortex A9 based board. Running linux. [Sat Apr 12 19:33:50.207 2014] [Sat Apr 12 19:33:50.207 2014] [Sat Apr 12 19:33:50.207 2014] U-Boot 2013.07 (Apr 09 2014 - 12:31:52) ...
21
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2answers
12k views

Why is swappiness set to 60 by default?

I just read some stuff about swappiness on Linux. I don't understand why the default is set to 60. According to me this parameter should be set to 10 in order to reduce swap. Swap is on my hard ...
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1answer
40 views

How to modify huge patch file properly?

I have this patch. I want to disable patching of Makefile and drivers/video/logo/logo_linux. What is best way of doing this? Do I edit it, and delete that specific entries? If so, is there a tool ...
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2answers
1k views

Kernel Mode Setting vs. Framebuffer?

With KMS, the graphics drivers are moved into the kernel. Since the framebuffer was already in the kernel, I wouldn't expect this to affect framebuffer operation. Yet, I read that KMS supercedes the ...
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2answers
732 views

What is the need of the struct thread_info in locating struct task_struct?

While reading through the Linux Device Drivers, I could understand that the Process Descriptor (of type struct task_struct) has all the info regarding a particular task. The process descriptors are ...
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1answer
932 views

Upgrading kernel 2.6.18 to 2.6.32 on CentOS 5.10

I've been looking on Google for 4 hours and I can't find a solution to my problem. I have a computer running CentOS 5.10 using Kernel 2.6.18-371.9.1.el5 and I would like to upgrade my kernel to ...
2
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1answer
1k views

Running make with vermagic kernel string with parentheses causes /bin/sh syntax error

I am on Ubuntu Server 12.04 x86_64 and I need to build Android CyanogenMod 7.2 kernel module. My phone has custom ROM and a patched kernel: adb shell cat /proc/version yields Linux version ...
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1answer
97 views

The meaning of Linux Kernel bug output

I have a quick, (maybe naive),question about Linux kernel's output. When I issue a command, the system (Ubuntu 12.04) freezes, the serial port output of this system is as follows: [ 373.805067] BUG: ...
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1answer
222 views

Debian + Linux kernel 3.12.22: “Kernel module loader” option is not available

The Debian guide for compiling a kernel says: Do not forget to select “Kernel module loader” in “Loadable module support” (it is not selected by default). If not included, your Debian installation ...
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1answer
67 views

Common code for kernel and userspace [closed]

I'm working on a linux project. I want to have some code (to be specific, a struct) and a header file (my own implementation) common to both the kernel and the userspace. Can someone tell me how to ...
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1answer
176 views

Debian: GPG cannot fetch Linux Kernel key

I am in the process of recompiling the kernel on Debian. Following the instructions on kernel.org, the first step is to verify the signature. But GPG complains that it cannot find the public key: # ...
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0answers
114 views

kernel build: why does 'make install' complain about missing modules?

I'm building a 3.2.x kernel on a RedHat Enterpise system. During 'make install' it takes a very long time and is complaining : ERROR: modinfo: could not find module xxx I assume its probing ...
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1answer
54 views

Automatized kernel upgrade

I am writing a BASH script that automatically configures, builds and installs the most recent kernel image. The generated kernel should include the grsecurity patchset. It would use the previous ...
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7answers
2k views

What's the difference of the Userland vs the Kernel?

I am trying to understand exactly what is userland? everyone that I ask says: "Anything that is not kernel". but it is not tangible for me. When I am reading that kernel can run that driver on the ...
3
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1answer
85 views

Open Character Device without creating a Device Node

I'm having an issue where a 3rd party application is opening a device node it shouldn't. I wrote a SPI Slave device driver that does some processing of messages. When the driver loads its in ...
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0answers
159 views

What does this “general protection fault” in my console mean, and how do I interpret it?

I had a couple of consoles open for other work and when I came back to them they both contained the following: Message from syslogd@Stacey-Windows at Jun 19 09:43:28 ... kernel:[ 4375.127165] ...
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2answers
110 views

Debian: get package name for installed file

I'm connected via SSH to a PC running Linux kernel 3.11.1: root@alix:~# uname -r 3.11.1 how can I find out which package installed this specific file or kernel version respectively? I tried ...
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5answers
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Where does uname get its information from?

Where does uname really get its information from? I figure this is something that should be straightforward. Unfortunately, I can't find any header containing just that information. Say someone ...
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5answers
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What is meant by “a system call” if not the implementation in the programing language?

I would like to understand the term "system call". I am familiar that system calls are used to get kernel services from a userspace application. The part i need clarification with is the difference ...
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5answers
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Benefit of kernel module compiled inside kernel?

What's the benefit of compiling kernel modules into the kernel (instead of as loadable modules)?
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3answers
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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 ...
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1answer
152 views

When is swap triggered or how to calculate swap_tendency?

I'm trying to use Redis for production services and trying to avoiding swapping, which is bad for performance. I had learn that swap is triggered by swap_tendency which is depending on ...
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1answer
109 views

How to verify that my uImage is good?

I had a zImage file and I used mkimage tool to convert it into a uImage format. When I am booting this file, it is not been found by u-boot: Wrong Image Format for bootm command ERROR: can't get ...
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1answer
76 views

Booting failing in different Debian and Debian derivated distros?

I've tried Ubuntu, Linux Mint and Debian, even though all have worked great for me I'm keeping with Ubuntu, I tested 12.04, 12.10 and even 13.04. The 12.04 LTS is the one I work with. There's one ...
2
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1answer
609 views

Realtek RTS5209 PCI-E Card Reader only work if card is inserted before boot

Hardware Info Laptop Model: Sony Vaio Pro 13 Problematic Hardware: Bulti-in Realtek Semiconductor Co., Ltd. RTS5209 PCI Express Card Reader Problem description Here is the problem, if I boot with ...
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1answer
80 views

Find out if CPU supports dynamic speed setting

I need to find out in my script if a (potentially legacy) CPU supports dynamic speed setting, and eventually get value of maximum and current speed. What makes it more complicated is that I need to ...
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4answers
2k views

IDE for large, multi-language projects (ie linux kernel)

I know the "which IDE do you guys use" question has been asked a million times. But I've never seen it asked in this context. What are some suggestions for an IDE when working on huge projects that ...
3
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1answer
2k views

vmlinuz and initrd not found after building the kernel?

After configuring and building the kernel using make, why don't I have vmlinuz-<version>-default.img and initrd-<version>.img, but only got a huge vmlinux binary (~150MB)?
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204 views

Updating kernel on a Chromebook to prep for Chrubuntu

Pretty simple question: I have read that by setting my Chromebook to the dev channel, it will install a later kernel. Currently it's 3.4.0, and it'd install 3.8.0 (64-bit, no less). However, after ...
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2answers
102 views

How to find out the bad block table offset and how to change it in u-Boot

I am facing a similar problem as this: Kernel does not recognize nand bad blocks marked by u-boot I'm using a friendlyARM micro2440 board that contains the s3c2440 ARM processor. u-Boot has found ...
2
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1answer
82 views

kernel event listener

I wonder if there is something similar to an event listener in UNIX that a program can subscribe to? Specifically I want to know: Start and end times of a user session Start and end of the ...
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1answer
151 views

MIC not working due to USB bandwidth

Using debian and centos, i get the same error when plugging my USB mic in. In Windows (xp thru 8.1) it works fine. [ 304.237543] usb 2-1.6.2: USB disconnect, device number 6 [ 305.220785] usb ...
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1answer
83 views

What causes /proc/<pid>/* resources to become owned by root, despite the procs being launched as a normal user?

I've noticed that some procs, such as bash, have their entire /proc/<pid>/ resources readable by the user who created that proc. However other procs, such as chrome or gnome-keyring-daemon, have ...
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2answers
563 views

Kernel freezes on loading ramdisk. How to find out what's wrong?

I'm using an Ubuntu Server (13.04) Minimal installation (with the Xubuntu Metapackage as a desktop environment, if that matters) on x86_64 on my Samsung notebook. I'm currently forced to use the ...
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2answers
138 views

How do I enable kernel option MMC_UNSAFE_RESUME

I am trying sleep and wake up my Kobo Mini ebook reader manually by using the command rtcwake. The reader is using busybox. cat /proc/version gives me this output: Linux version 2.6.35.3-850-gbc67621+ ...
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0answers
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Adding IPVS to the kernel

I am trying to setup keepalived on a pair of VPS load balancer servers. I have hit the road block of IPVS not being included with the kernal. IPVS: Can't initialize ipvs: Protocol not available I ...
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0answers
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Intel Xeon stuck at 800mhz CPU Freq on RHEL 6.5 [duplicate]

Currently running into a headache trying to figure out why my CPU speed is stuck as such a low frequency. After doing some research, I found that cpuspeedutil does actually control the state of the ...