The kernel of operating systems popularly known as Linux, or sometimes GNU/Linux.

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379 views

Compile the Ubuntu “Raring” Kernel with the Intel Compiler

Of course, the first question is: why I'm doing this. Just for fun! I'm learning more about Linux kernels and I have a virtual machine that I can replace in 15 minutes. Getting to business, I don't ...
2
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1answer
277 views

How enable watchdog?

I'm struggling with the watchdog timer (wdt) for a while. I can't get it working. My microcontroller is a AriaG25, based on the AT91SAM925. I have used this tutorial to compile the kernel. The ...
2
votes
1answer
60 views

Monitoring file reads for cache warming

After adding more memory to my Linux machine I was tempted to use the cache more agressively. The thing is: I boot up my machine, go to bathroom, come back and log in. It takes like half a minute to ...
0
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1answer
59 views

What part of the Linux kernel determines the execution order of userland apps? [closed]

Stripping the source, I can't pinpoint which part of the kernel sets and manages the userland apps, and how it does it. For example, in the Linux main source, is the procedure have options to set ...
2
votes
1answer
721 views

How to learn kernel programming from the start? [closed]

I have completed my graduation recently. And I have only basic knowledge in C. But I would like to work on the Linux Kernel, and customize it according to my needs. Not only customize I would also ...
2
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0answers
195 views

how to stop kernel threads preempting real time user space processes?

I created some processes in user space and tried to visualize its working in kernelshark with the trace recorded using trace-cmd. But kernel processes like the ones shown below are preempting my ...
2
votes
1answer
418 views

CONFIG_RTC_SYSTOHC: how to use the NTP synchronization option in the kernel

I have noticed in kernel 3.10, there is an option CONFIG_RTC_SYSTOHC Device Drivers -> RTC -> Set the RTC time based on NTP synchronization The help says: If you say yes here, the system ...
3
votes
2answers
969 views

Which file in kernel specifies fork(), vfork()… to use sys_clone() system call

When ltrace is used for tracing the system calls, I could see that fork() uses sys_clone() rather than sys_fork(). But I couldnt find the linux source where it is defined. My program is ...
3
votes
1answer
131 views

How can I override the kernel default options for mount?

I'm struggling with a program that creates a file system in a file and mounts it as a loopback device. The purpose of the program is to create a clone of the root file system and it thinks it's being ...
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3answers
111 views

Does a fault in a kernel module necessarily result in a system crash?

Or is it possible to overcome the fault, since the code isn't in the monolithic part of the kernel?
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3answers
2k views

Does the kernel have a main() function? [closed]

I am learning device drivers and Kernel programming. According to Jonathan Corbet's book, there is no main() function in device drivers. So I two questions: Why don't we need a main() function in ...
2
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2answers
1k views

Install kernel-devel of specific version in fedora 19

So I have different "installed" kernel versions from the running kernel version, on my fedora 19 machine. To give a more clear idea, here is my terminal output: [user@home ~]$ uname -r ...
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4answers
5k views

Can I create a virtual ethernet interface named eth0?

This is a rather odd question, because normally it would not make sense to do that. I am running Arch based on the Linux 3.10.5-1 kernel. The system uses the new de-facto naming conventions of ...
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0answers
356 views

PC sudden shutdown, Sensors show normal temps, Thermal event interrupts shows 1276

I'm experiencing sudden shutdowns on my Linux systems. Using Ubuntu 12.04, my kernel version is 3.5.0-37-generic #58~precise1-Ubuntu. Running a Acer M5 581t(G) with 6 gigs ram laptop. I have been ...
2
votes
1answer
201 views

Generate interrupts for purpose of stress testing

I'm testing the quality of a generated PWM signal on a Raspbery Pi. I would like to test how it behaves if there are lots of interrupts coming. Is there a way to fake interrupts or force 2000 ...
1
vote
1answer
591 views

Beaglebone Black Device Tree for LCD4 cape

The device tree for LCD4 cape is located at /lib/firmware/BB-BONE-LCD4-01-00A1.dts When I looked into it, the declaration of those GPIO buttons confuse me. There are five buttons according to ...
0
votes
1answer
77 views

Building Linux from Scratch stuck, incompatible sed version? [duplicate]

I am trying to build Linux from Scratch per LFS website While I was able to install all the packages until 6.7.1 without any error, I am stuck at Installation of Linux API headers (This is after I ...
7
votes
2answers
230 views

Strange temporary network outage in Linux

I'm facing a very annoying problem that I noticed a week from now and for which I can't find an answer: my network suddenly stops responding, usually coming back exactly 25 seconds later. I was using ...
2
votes
2answers
1k views

Linux (debian/testing) cannot boot after installing kernel 3.9.1

Today I wanted to upgrade the kernel on my debian/testing system from 2.6.32-5-686 to 3.9-1-686-pae. So I installed the image by sudo aptitude install linux-image-3.9.1-686-pae (or something like ...
1
vote
1answer
159 views

What value is stored in linux xtime variable?

Whenever I print the value of /proc/interrupts the value of rtc0 in IRQ8 which is for RTC shows only 1 interrupt on CPU0. I have read that when booting the value of the xtime variable is stored from ...
2
votes
1answer
372 views

Why CONFIG_NO_HZ is not set by default

In the Linux Kernel CONFIG_NO_HZ is not set. But an initial reading suggests that setting that option would be nice from a performance point of view. But reading some posts like this made me think ...
1
vote
1answer
86 views

Why can't new versions of kernel solve the backlight problem?

Currently I am using Linux 3.8.0-27-generic kernel on my Samsung laptop. I replaced grub configuration file with the following text to make backlight control work: GRUB_CMDLINE_LINUX_DEFAULT="quiet ...
3
votes
1answer
973 views

What is meant by interrupt remapping in Linux?

Can anyone explain what the interrupt remapping is? Would turning this feature off in the Linux kernel cause any problems, or bring any benefits?
1
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1answer
142 views

Efficiency of Linux Kernel [closed]

In a documentary, Linus Torvalds says that even in the future, if anyone wishes to make a new OS from the scratch, they could use the Kernel which he wrote. It was very inspiring. Is it true that ...
2
votes
2answers
724 views

Can system calls be interrupted?

Please comment on the following sentence: On the standard Linux kernel without the rt patch, interrupts can't interrupt ongoing system calls. The reason why our machine doesn't stop working ...
2
votes
1answer
309 views

Are time interrupts always followed by a scheduler call?

When a timer interrupt occurred the ISR is called to service the interrupt. Is it okay to assume that every timer interrupt ends with a call to the scheduler on which process should continue running ...
0
votes
1answer
49 views

CentOS - acts abnormal every week and causes my whole setup to be down, how can I rollback / restore back to one week?

I have CentOS and Red hat enterprise Linux running, where I have now working Google Apps Engine and related other Python web applications. Every week or depending on any Google Apps Engine latest ...
1
vote
0answers
76 views

boot updated kernel image on beagleboard

Boot updated kernel image on beagleboard. I had installed a kernel on Beagle-board to update image of kernel to it. I've used this command: $ sudo apt-get install linux-image-3.2.0.49-omap It ...
2
votes
1answer
563 views

What are PCI quirks?

I hear a lot about PCI quirks when reading about the Linux kernel, but no website explains or defines PCI quirks. What are PCI quirks?
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2answers
417 views

How can I know if the current kernel was compiled with a certain option enabled?

Is there a way to know if the kernel was compiled with a certain option activated (i.e. CONFIG_PROC_EVENTS=y) without having to pull out the kernel sources package and looking in the config file?
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0answers
167 views

Will there be any security problem to permit non-root user set up a loopback devices?

if the user has full access to the image file (iso or disk image), will there be any security problem to permit him set up a loopback device backed by this file ? % ls -al /dev/loop* ...
2
votes
2answers
2k views

How to 'strace' a unix domain socket?

Kind of hard to explain but I noticed when straceing the PID that has the socket open I cannot see any of the communication. How can I sit in the middle of a socket file to watch communication?
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0answers
248 views

Allocated Memory difference in xen guests after using Linux 3+ kernel [closed]

Can someone explain to me why there is a memory difference in Guests with the same configuration? Hypervisor: xen 4.2 64 bit VM1: Centos 5.7 with 2.6.18-274.el5xen Assigned memory from xen is ...
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1answer
64 views

Significance of certain folders in linux kernel tree

While going through Linux Kernel Source tree, found certain folders, explanation of which was not seen in the popular sites. Could someone tell why these folders are there like: block - This is not ...
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0answers
55 views

configure allowed_tcp_congestion_control via config files in linux kernel

I am trying to come up with a custom set of TCP congestion control variants as part of the tcp_allowed_congestion_control. I do have multiple variants on my tcp_available_congestion_control list but ...
1
vote
1answer
2k views

Is “sync” before drop_caches necessary?

I have read a lot of docs saying, it is good idea to do a sync before doing echo [1,2,3] > /proc/sys/vm/drop_caches. I am not able to understand why it is needed, since drop_cache is a ...
4
votes
1answer
128 views

what is the linux boot param “memmap” equivalent in freebsd

In linux kernel, there is an option to reserve a portion of system ram i.e memmap=512M$2G (boot param) Here 512M starting from 2G would be reserved and not available to OS What is the equivalent in ...
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votes
2answers
45 views

Resuming the Linux Kernel Configuration

I am configuring a Linux kernel before I compile the code. However, after I was thirty minutes into answering the many questions concerning various kernel settings, I accidentally pressed Ctrl+C. I do ...
1
vote
1answer
622 views

How to log iptables as of kernel 3.9.0?

What is the right way to log iptables as of kernel 3.9.0? I can no longer append a logging rule such as: # iptables --new-chain droplog # iptables --append droplog --jump LOG --log-level info ...
0
votes
1answer
220 views

After upgrading to linux kernel 3.9, kde does not start correctly

I recently upgrade my debian from kernel 3.2 to 3.9. This leads to a strange problem. After booting to kernel 3.9, it directly goes to tty7 instead of kde login. I can identify that kdm is up and ...
2
votes
0answers
156 views

What changed between kernels 3.7 and 3.9 that affects LVM/RAID root file systems?

I'm trying to fix a (very messy) system that the user hosed by running a kernel upgrade from 3.7.10 to 3.9.6. the root file system is on an LVM volume on top of a software RAID array. The boot manager ...
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vote
0answers
168 views

Understanding the Buddy Allocator [closed]

I have a conceptual doubt in understanding the way Linux Kernel manages Free blocks. Here is what I interpreted through reading so far. The Buddy Allocator implementation is allocation scheme that ...
2
votes
1answer
88 views

How can I find the Secure Attention Key (SAK) on my system and can I disable it?

In answer to My process was killed but I cannot understand the kernel notice, I was pointed to some documentation on the Secure Attention Key (SAK) on Linux. I have a embedded system generated using ...
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votes
1answer
39 views

get Various types of address used [closed]

How to get various address ranges of a running machine or a crash dump? User virtual address Physical address Bus address Kernel logical address Kernel virtual address I don't need the bus ...
1
vote
2answers
89 views

Download the Complete Linux Kernel Collection

I am wanting to download EVERY version of the Linux kernel as source code, Debian files, and RPM files. Where can I find a single site where I can download them all at once? If that is not possible, I ...
4
votes
2answers
1k views

How do I get a linux kernel patch set from the mailing list?

I don't subscribe to the linux-kernel mailing list, but I want to get a set of patches that were posted a few weeks ago and apply them to my kernel for testing. I'm very familiar with patching, ...
3
votes
1answer
135 views

What do the fields in the libata device probe line in dmesg mean?

When the kernel boots, it prints out lines like this for each SATA device: [ 0.919450] ata2.00: ATA-8: ST2000DM001-1CH164, CC24, max UDMA/133 [ 0.919487] ata2.00: 3907029168 sectors, multi 16: ...
2
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2answers
437 views

Enabling UTS Namespaces in the Linux Kernel

When configuring the Linux kernel, what are the advantages and disadvantages of enabling UTS namespaces? Would the new system be harmed if UTS namespaces were disabled?
0
votes
1answer
1k views

Understanding RCU when Configuring the Linux Kernel

I am configuring the Linux kernel version 3.9.4. I am being asked questions about RCU (seen below). Specifically, what are each of these and what are the advantages and disadvantages of enabling or ...
3
votes
0answers
170 views

How to set CONFIG_PREEMPT_NONE in RHEL 6.4 (linux)

I am trying to tune the RHEL6.4 Kernel to handle server style load for of my application. With RHEL 6 scheduler has been changed to CFS and with RHEL 5 my application works fine. I would like change ...