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

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12
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2answers
880 views

Is it good to have multiple version of Linux Kernel?

Once, I was installing some kernel patches & something went wrong on a live server where we had hundreds of clients. Only one kernel was there in the system. So, the server was down for some time, ...
3
votes
1answer
101 views

bash runs out of memory

This question is a fork of this SO question. Here is the MCVE version: $ PS1='Parent-$ ' Parent-$ type seq seq is /usr/bin/seq Parent-$ bash $ PS1='Child-$ ' Child-$ for i in $(seq 1000000000); do ...
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0answers
72 views

Using DKMS, to automatically patch and install kernel on update

I have a system that needs patching a file in kernel to work properly. The system is running Ubuntu 14.04. The patch patches a file in drivers/hwmon. So after every kernel update I need to download ...
3
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1answer
100 views

Building a minimal linux

I have been following A Minimal Linux System from Scratch in order to build a Linux with a small footprint (10MB or less). I'm fairly certain that there were no errors up until the last point, where ...
0
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0answers
117 views

Avoid Booting Fedora in Failsafe Mode

I recently bought a Lenovo G50-45 and managed to setup a dual boot system with Windows 8.1 and Fedora 21 (UEFI booting). But when I boot Fedora, the following error message shows up: [1.079848] EFI: ...
0
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0answers
74 views

Linux Kernel Panic and Problem with boot

I have installed CentOS 6.4 on VmWare Workstation (Win 8 as Host OS). I worked with it for several days, but suddenly when I rebooted it, it did not boot properly and on stopped with this error : ...
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0answers
25 views

Investigating Active MemInfo

I am seeing high Active usage when I do a cat /proc/meminfo : MemTotal: 65965328 kB MemFree: 51640992 kB Buffers: 1050332 kB Cached: 8516112 kB SwapCached: 0 kB Active: 11512732 kB Inactive: 1878028 ...
3
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0answers
111 views

How to prevent kernel or any broadcast messages from flooding the TTYs?

Because of some hot-plugging issue, similar to what talked of here, the TTY displays show a continuous stream of messages (which are also logged in the /var/log directory). Every text I key in flows ...
0
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1answer
236 views

What is MCH_SSKPD warning in dmesg?

While i was reading dmesg log just to check that everything is fine, i met [ 18.956187] [drm] Wrong MCH_SSKPD value: 0x16040307 [ 18.956190] [drm] This can cause pipe underruns and display ...
0
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0answers
126 views

No brightness control for opensuse 13.2?

I have posted on brightness issue Here!! After upgrade to KDE 5 Now i cannot change brightness through controls !! AND ALL FUNCTION KEYS (wireless,brightness,touchpad,sound +/-) are not working ...
-2
votes
1answer
34 views

Is it neccessary for me to update my kernel? And how? [closed]

I'm trying to install Kubuntu on a VM in order to do some deep learning following this guide: https://github.com/BVLC/caffe/wiki/Ubuntu-14.04-VirtualBox-VM I'm stuck in the step of the guide that ...
0
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0answers
2k views

nl80211 not found

Environment Linux 3.0.8 compiled for ARM FriendlyARM mini210s I cross-compiled iw for an ARM board (friendlyARM mini210s), when I installed the utility and ran it, I got this message: # iw --help ...
1
vote
2answers
459 views

How to properly build a minimal FreeBSD kernel?

Is there any proper way to build a minimal kernel for FreeBSD? The FreeBSD Handbook has the lack of information about this. By default /boot/kernel directory has the pretty big size - around 450MB. I ...
0
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0answers
67 views

Syslog message “rt_bind_peer(0) @ffffffffa0283f57”, twice in every second

My /var/log/syslog on a Debian server is flooded with lines similar to: Dec 23 16:05:40 server1 kernel: [ 686.957585] rt_bind_peer(0) @ffffffffa0283f57 These messages occur up to twice a second ...
0
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1answer
37 views

Does iptables protect from kernel vulnerabilities? [closed]

I read a lot of kernel vulnerabilities which are beyond my understanding. I would like to reduce the risk of an issue related to one. If I block everything other than SSH on a server, will this help ...
-1
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1answer
45 views

Is the kernel version fixed within the life of a release/version of each Linux distribution?

I read the Table of versions of List of Ubuntu releases. I found that the kernel version for each release is fixed. E.g. the kernel is 2.6.24 for Ubuntu 8.04, 2.6.32 for 10.04, 3.2+ for 12.04, and ...
2
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2answers
81 views

Why is userspace slower than the kernel?

I've heard that FUSE-based filesystems are notoriously slow because they are implemented in a userspace program. What is it about userspace that is slower than the kernel?
4
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1answer
90 views

what's the difference between page cache and buffer cache?

In linux OS, you can type command "echo 3 > /proc/sys/vm/drop_cache" to release memory, and you can type command "sync" to release the memory. And in linux kernel there are two kind of cache, one is ...
0
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1answer
59 views

Custom Kernel to Disable SATA and USB Devices

I am setting up diskless clients that will run on an internal network. I have disabled SATA and USB ports using a BIOS locked with a password, but this is easy to get around by using the jumper to ...
1
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2answers
81 views

Is system call the only way that a user program can intentionally affect the state of a Linux kernel?

I think there are several ways that a user program can intentionally affect the state of a Linux kernel. By invoking a system call; By invoking mmap() and writing the memory that has been mapped to ...
3
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1answer
341 views

Can the hard drive timeout be disabled in Linux (attempting task abort)

Unfortunately, when a hard drive (usually a virtual drive) is slow, Linux aborts requests to that drive after a timeout, possibly causing data corruption. Last time this happened to me, I had 2 vms ...
6
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1answer
203 views

Some basic questions about Linux kernel's security [closed]

I don't know much about Linux kernel, and I have some questions. What is the main purpose of separating kernel memory from user-space memory? To make sure that a user application cannot do anything ...
0
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0answers
85 views

different ways how Linux TCP/IP stack terminates connection

I have a Linux machine which connects to SSH server with SSH client(OpenSSH_4.1p1). SSH client machine has IP address 10.10.11.1 and SSH server has IP address 10.10.10.1. SSH client has kernel version ...
1
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1answer
33 views

take the DRAM performance of the processes into consideration when scheduling

The CFS scheduler in Linux schedules the processes based on the virtual runtime of CPU. But, the DRAM memory is the bottleneck in most of the emerging domains. Why not take the DRAM performance of ...
0
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1answer
34 views

Disallow change of init kernel parameter

is there any way to disallow changing init parameter on boot time? I want to prevent situation when someone reboot my server, edit grub entry and get access without password. Maybe some kernel ...
0
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2answers
112 views

When building a new kernel in OpenBSD 5.6, can the name of `config` be something else?

I am using the release version of OpenBSD 5.6 and have to apply a patch called 004_kernexec.patch.sig (URL: http://ftp.openbsd.org/pub/OpenBSD/patches/5.6/common/004_kernexec.patch.sig ) An excerpt ...
2
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1answer
36 views

does the second kernel need kexec enabled

It's clear that you need the kexec syscalls in the 'first' kernel. But does the kernel that should get loaded (with kexec_load and reboot) need to be compiled with kexec? If yes, what extra code ...
0
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0answers
60 views

linux vlan bridge feature backport to 2.6 kernels

The VLAN-aware bridge was introduced to the Linux mainline on the 3.x kernels, according to this article on lwn: VLAN filtering/VLAN aware bridge Has this feature been backported to the 2.x kernels ...
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0answers
38 views

3.10.17 Kernel i2c buses missing on embeded system

On my ARM embeded system I have 4 i2c buses and only one shows up in /dev and in /sys/device/... folders. Other 3 i2c buses are not loaded. There is also no warning message inside dmesg, but there is ...
1
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1answer
487 views

BUG: scheduling while atomic

I have just installed Linux (OpenSUSE), and when start the OS, I get an error BUG: scheduling while atomic: systemd_udevd plymounthd... what does it mean?
0
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0answers
49 views

Suspend Crash in android 4.4

During suspend clocks are not turning off, meanwhile when we resume clocks are not getting turning on. I am getting crash like <4>[ 216.945252] WARNING: at ...
3
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2answers
473 views

What does LTR kernel mean?

I was reading some sites and came across (LTR) by the number of kernel. Can somebody explain what is means?
0
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1answer
331 views

Cannot boot latest kernel update after installing on new system

I recently built my own computer, and I was excited to finally get to the installation of the operating system. I chose Fedora 20 to use as my primary operating system, and I was able to successfully ...
0
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1answer
518 views

cc1: warnings being treated as errors when compile FreeBSD 8.2 Release

I am trying to compile FreeBsd 8.2 RELEASE kernel # uname -a FreeBSD 8.2-RELEASE FreeBSD 8.2-RELEASE #2: Sun May 18 00:07:10 PDT 2014 Build the kernel # pwd /usr/src # make buildkernel ... it ...
0
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1answer
46 views

Is hardware helping reducing crashes of OS X? [closed]

I am taking an OS course this semester, and we mentioned that device drivers can cause about 85% of crashes(for Windows). My understanding is that: since many personal computers are configured with a ...
0
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0answers
87 views

CPU load and power management (frequency)

question background In my understanding the load value (shown e.g. by top) allows (together with the knowledge how many CPU cores the system has) a very quick assessment which share of the ...
0
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0answers
191 views

loading ath9k_htc kernel driver fails

could someone please point me in the right direction to get my external wireless stick (TL-WN722N) working on my Xperia Neo (haida) smartphone? So far I've done the following: I downloaded ...
0
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0answers
81 views

Debian Squeeze: TCP/ICMP stops working suddenly (R8169 Driver)

we suddenly see our NETWORKING stops (TCP/UDP/ICMP) in our client system. tcp: We tried reaching our server every 5 seconds.But , there was no connection establishment TCPDUMP REF: ...
1
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1answer
160 views

Error compiling buildroot

I updated my buildroot for the version "2014.08" (stable version) and I updated the Kernel version (3.12.26) of my project, when the buildroot try to build the linux-headers-3.12.26 package, occurs ...
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0answers
22 views

What exactly does struct nfs_unlinkdata do?

I been reading the source code of unlink() but i am stuck on nfs_unlinkdata and i can't find anything on it on the web. Thanks a lot for your help.
1
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0answers
54 views

HD 4800 lower fan speed

I've installed Linux Mint 17, most important thing for me is to lower the fan speed to 30% as I am doing in Windows because it's really too noisy. Note that the temperature stays at ~50°, so this ...
1
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0answers
42 views

real time kernel / low latency comes from the vanilla source

Does the vanilla source provide real time / low latency functionality ?
5
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0answers
62 views

NTPD Nanokernel

I had a couple of questions about the NTP Nanokernel as explained here: http://www.eecis.udel.edu/~mills/database/brief/nano/nano.pdf The big question is how does this Nanokernel manage to deliver an ...
0
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1answer
30 views

module prints to kernel log with delay

I've created a basic linux kernel module, which does the following: static __init int init(void) { printk(KERN_DEBUG "Banana"); return 0; } And of course: module_init(init); Strangely, I ...
2
votes
1answer
62 views

ifup wlan0 causes kernel Oops

on my laptop, when I do ifup wlan0, sometimes I get following call trace in dmesg. Other times, the log looks perfectly normal, and there are no kernel Oops messages. In both cases (with errors and ...
2
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1answer
107 views

Does each network packet cause an interrupt to CPU?

While I know that lot of packet processing(CRC calculations, packet segmentation handling, etc) can be offloaded to NIC, then does each packet still cause an interrupt to CPU? Is there a difference if ...
0
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0answers
68 views

latest arch linux on beaglebone black

I have installed arch linux using what I assumed was the latest kernel at http://archlinuxarm.org/os/ArchLinuxARM-am33x-latest.tar.gz But this only installs 3.8.13 and I understand that there are ...
0
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1answer
80 views

Changing linux config from 32 bit to 64 bit loses RTC

I have a config from a 32-bit linux 3.12.18, and was trying to compile a 64 bit version with most settings like selected drivers etc. the same as in 32 bit version. For this I used make menuconfig ...
0
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0answers
71 views

Changing CPU frequency programmatically

I have seen that standard CPU Frequency driver(comes with default package with linux kernel) can change the CPU frequency at runtime, when being used under the supervision of "Ondemand" governor. ...
1
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1answer
328 views

Kernel 3.14 not working with ATIProprietary fglrx?

On my debian laptop I installed kernel 3.14 so I have the alx driver so my ethernet works, I originally had the 3.2 kernel (Debian 7.7). AFter installing the new kernel, gnome3 went back to the ...