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

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Do I have to compile the kernel every time, even for a small change?

In my project I configure the kernel (2.6.32) in block/ioctl.c. We all know that kernel compiling and building takes few hours. Even for a small change, I'm compiling from scratch. So is there any way ...
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0answers
51 views

Passing data from kernel space to user space in FreeBSD [closed]

I need some information regarding write requests from all applications on FreeBSD. I put a function inside the file system write call ffs_write() which collects the information into an array of ...
4
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1answer
62 views

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 ...
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3answers
90 views

Placement of kernel binary and sources for kernel module building?

I'm trying to setup an environment for kernel module development in Linux. I've built the kernel in the home folder and would like to place the sources and binaries to the correct place so include ...
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1answer
421 views

Setting up HDMI output from Linux console

I am currently running Debian Wheezy on a HP Microserver N54L with an AMD Radeon 5450 video card. I would like to be able to play audio from the console through the HDMI port of my video card and ...
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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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0answers
16 views

how get net switch info in soc?

I have a router device. cpu is mtk7620n. mtk7620n have a switch. How can i get information of the switch . swconfig show nothing. i think the switch have no driver. Anybody give me some ...
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1answer
61 views

Starting my own application at the startup

I am working on zc702 board having ARM Cortex A 9 processor. I have a binary that I got after cross-compilation for ARM (LED blinking). Now I want that this file should execute as soon as the the ...
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2answers
161 views

Are system calls the only way to interact with the Linux kernel from user land?

Are there any other interfaces, e.g. the /proc filesystem?
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74 views

How to create a custom Linux distribution? [closed]

Can any one tell me the easiest way to create a system with live cd with installing function. Which can install backtrack all tools?? I need to create a custom boot animation and everything!
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1answer
35 views

What is the difference/relation between kernel name and OS name?

What is the difference/relation between kernel name and OS name? Are they always the same thing? For example, I am puzzled at the outputs: -bash-4.1$ uname -s Linux -bash-4.1$ uname -o GNU/Linux ...
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2answers
126 views

What is the difference of kernel/distribution's release and version?

I use the following command to see the name, release and version of a kernel. -bash-4.1$ uname -s Linux -bash-4.1$ uname -r 2.6.32-279.el6.x86_64 -bash-4.1$ uname -v #1 SMP Wed Jun 13 18:24:36 EDT ...
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3answers
172 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) ...
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1answer
51 views

Correct location of initramfs.cpio file when compiling kernel

I am following this article and generated an initramfs.cpio file. Now the tutorial mentiones that I have to put this file in build directory: Finally, you have to rebuild the kernel again: # 0. ...
3
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1answer
157 views

Why isn't “REISUB” working on Debian?

I'm using Debian 'Jessie'. Sometimes my computer freezes, and then I can't use Ctrl+Alt+Supr to reboot, Ctrl+Alt+Backspace to kill the X Window System nor Ctrl+Alt+F1 to open a new shell. I've read ...
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139 views

Ping IP works, nslookup fails. New Kernel

I am compiling my own 3.14 kernel. I fear I may have left out some important networking feature to get DNS working. I can't resolve domain names. I can ping my DNS server. I can resolve using that ...
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0answers
1k views

Kernel panic not syncing : Attempted to kill init

OEL 5.9 (Tikanga) 2.6.18-371.6.1.0.1.el5 On boot I get the following errors: ... exec of init (/sbin/init) failed!!!: No such file of directory Kernel panic - not syncing - Attempted to ...
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3answers
98 views

Enabling IP forwarding at kernel compile time

I am compiling a kernel for a router. I know a way to enable IP forwarding in an existing Linux system. At compile time, CONFIG_IP_FORWARD is said to do the same task. I am configuring version ...
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1answer
48 views

How to use a built in driver in the kernel?

I am building the 3.14 kernel for a board that requires the intel e1000e driver. I would like this kernel to have the driver built in so that I can remove loadable module support. I have chosen the ...
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1answer
34 views

Where are the files created by “make modules” when building and compiling the Linux kernel?

To build the kernel, I do make menuconfig make make modules For step3, where do the files go? What's the location for modules? Can I change it by using any env variables?
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1answer
70 views

Kernel optimiziations for ioctl AF_INET operations

Our server solution handles many tunnel operation requests (add/update/delete) using the ioctl interface, and the AF_INET address family socket. Aprox. numbers are 100 operations/minute with over 8k ...
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2answers
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Newly compiled kernel not booting up (vanilla kernel 3.12.14)

I downloaded, configured and installed kernel downloaded from kernel.org. While booting up this new kernel for the first time, this error screen shows which is pointing towards a missing or wrongly ...
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1answer
180 views

Can the 25 years of development of the Linux kernel be qualified or abstracted in layman's terms? [closed]

The Linux kernel is almost 25 years old. If I had to come up with the short version on the development history of the Linux kernel since 1991(its inception date), and in partcular since 1994 (1.0.0) ...
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1answer
47 views

Can a real-time process exist in the 'expired' queue of linux kernel?

In the Linux kernel 2.4: Real-time processes are given a priority of 0-99 and they co-exist in the ready queue along with the nice processes (who's priority goes between 100 and 139). But real-time ...
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1answer
162 views

Why is swap used when a lot of memory is still free? [duplicate]

In the below 2.6.18 Linux Kernel (Red Hat) server, there is a lot of free memory, but I see some swap is used. I always thought of swap as an overflow when memory has been depleted. Why would it ...
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140 views

Does an in-kernel firewall sit between the network access layer and Internet layer?

This question is a follow-up to my previous question. Logic for me to says that an in-kernel firewall sits between the network access layer and the Internet layer, because it needs to have access to ...
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1answer
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How security programs like firewall, IPS and IDS have access to network data?

It is said that kernel responsible for the transport, internet and network access layers for a network data. Then, the network data is passed on the appropriate process based on port number. How ...
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1answer
48 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
200 views

How we can avoid rebooting the system after partition change with fdisk?

When modifying the partition table, fdisk usually returns the following error message: WARNING: Re-reading the partition table failed with error 16: Device or resource busy. The kernel still ...
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3answers
196 views

How does one capture traffic on virtual interfaces?

I would like to capture traffic on Linux virtual interfaces, for debugging purposes. I have been experimenting with veth, tun and dummy interface types; on all three, I am having trouble getting ...
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1answer
165 views

Why isn't the -rt (RT-Preempt) kernel patch included by default in the mainline kernel?

According to https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO , the RT-Preempt patch converts Linux into a fully preemptible kernel. The magic is done by: Making in-kernel locking-primitives ...
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How to automate configuration of the Linux kernel build

I'm compiling a flavor of the Linux kernel based on the default configuration (for an ODROID system), with some additional features enabled. I want to automate this process so that I don't have to ...
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Process in user mode switch to kernel mode. Then the process will have root privileges?

According to http://www.linfo.org/kernel_mode.html in paragraph 7: When a user process runs a portion of the kernel code via a system call, the process temporarily becomes a kernel process and is ...
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How to correctly set kernel command parameter for sdboot

Thease are the kernel command line parameter Kernel command line (user set) root=/dev/mmcblk0p2 rw rootwait console=ttyPS0,115200 I am trying to run linux from sd card, and the file ...
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1answer
203 views

What is the relationship between root and kernel? [closed]

Based on part of the first answer of this questions: read from a file (the kernel must check that the permissions allow you to read from said file, and then the kernel carries out the actual ...
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1answer
48 views

Result from kernel returned to what process?

When a process requires actions that require kernel mode, it uses a system call. So, how are the results returned to the process?
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3answers
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What happens when I run the command cat /proc/cpuinfo?

What happens when I write cat /proc/cpuinfo. Is that a named pipe (or something else) to the OS which reads the CPU info on the fly and generate that text each time I call it?
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Is my understanding of kernels correct? [closed]

System: Application OS: Scheduler, VMM, IPC, FS Drivers, dispatchers, VFS The above would be a monolithic kernel. In a monolithic kernel all core OS functions are separate from user space. Functions ...
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Does ksplice work with updates from repos?

If there is a kernel update from an upstream repository (such as debian or centos) does ksplice work with those updates? If not, how does one update the kernel without a reboot and without paying ...
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1answer
858 views

usb kernel module does not load on demand but works fine with insmod and modprobe from the shell

I have a USB Linux Kernel module that compiles and builds. Running insmod loads my module and dmseg and tail -f /var/log/debug shows me it works as expected. Running depmod -a then modprobe from the ...
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1answer
191 views

High performance routing with high churn ruleset. What approach is most likely to scale to C10K and beyond?

I've been asked to create a high throughput router using PC / server hardware. I'm modestly familiar with pf, iptables, and tc, but I've never had such high churn and so many rules. I hope you can ...
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3answers
361 views

What defines the maximum size for a command single argument?

I was under the impression that the maximum length of a single argument was not the problem here so much as the total size of the overall argument array plus the size of the environment, which is ...
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1answer
155 views

What is the “kernel build”, and where do I get it?

I am trying to compile OpenOnload from Solarflare for my nic on a server that I'm building. It is saying something about not having a kernel build. root@server:/usr/src/openonload-201310-u2# ...
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1answer
46 views

Linux Web Kiosk [duplicate]

Hi I'm having a idea of develop a light weight Linux kernel which will boot and open a web browser in full screen and request data from pre define URL. Can any one give me some guides on this please. ...
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1answer
38 views

Different Kernel in /boot and the kernel built tree [closed]

I discovered after a binary comparision that my old kernel in /boot was different from the kernel that I had built and kept backed up in the kernel source tree. A while ago I also had a few ...
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0answers
182 views

Wireless constantly reconnecting on Ideapad running Arch

I just bought a new laptop, a Lenovo IdeaPad U330 touch, and after some struggle (with the Secure Boot stupidity) I have managed to install Arch Linux. I have configured my system, installed all the ...
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628 views

How exactly does printk work internally?

I know printf needs help from the OS to do its job. I also know printf does not work in the Linux source code as there is no library. And so we have printk for debugging. How does printk work ...
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1answer
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Linking option while installing Linux [closed]

I have installed Linux kernel from source. The way I do this is that I first do make menuconfig and then make inside the root directory of the source code. As a result of this I get a an ...
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2answers
233 views

How does a bootloader and kernel interact after the kernel is loaded in memory?

I'm a little bit confused about the role of bootloader and its interaction with kernel, especially when talking wrt ARM Llnux. Once the Kernel is loaded into RAM, is there any job left for the ...
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Starting Bootlog daemon: bootlogd

Whenever I run linux on many ARM based systems, I see a message like this: Starting Bootlog daemon: bootlogd. As can be seen from the log messages below, it takes some finite time, close to 0.5 ...