Tagged Questions

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

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1
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0answers
18 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
22 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 ...
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0answers
22 views

real time kernel / low latency comes from the vanilla source

Does the vanilla source provide real time / low latency functionality ?
3
votes
0answers
21 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
19 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 ...
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0answers
14 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
44 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
30 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
19 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 ...
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0answers
23 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. ...
0
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0answers
8 views

How to add new systemcall in Linux 3.2.x? [migrated]

I'm new to Linux, and I want to compile my kernel for Debian-amd64 with a new system call. The only tutorial I could find online was for a i386 or x86 system. I followed their instructions but at the ...
1
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1answer
71 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 ...
12
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2answers
763 views

memory limit of the Linux kernel

I have a perplexing problem. I have a library which uses sg for executing customized CDBs. There are a couple of systems which routinely have issues with memory allocation in sg. Usually, the sg ...
1
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1answer
31 views

Walk-through into make (menu)config's options [closed]

I need to customize the kernel a lot for a custom system. Most of my changes concern the kernel's memory usage (something like an embedded kernel). There are a lot of things enabled by default in the ...
0
votes
2answers
28 views

Fatal error: linux/smp_lock.h: no such file or directory when trying to compile tiusb

I am trying to compile the TI-Graph Link USB Drivers? So I downloaded it, and ran make in the directory libusb. It produced the following: ~/Téléchargements/tiusb/tiusb-1.10$ make make -C ...
1
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0answers
28 views

How to suppress input overrun messages

I have a Raspberry Pi running Raspbian (a Debian flavor: Linux version 3.12-1-rpi (debian-kernel@lists.debian.org) (gcc version 4.7.2 (Debian 4.7.2-5+rpi1) ) #1 Debian 3.12.9-1+rpi1 (2014-05-19) ). ...
5
votes
1answer
112 views

Calls to sync/fsync slow down after 30 minutes uptime

After 30 minutes of uptime using Ubuntu 14.04 with a hybrid SSD I see many processes blocking IO using iotop. This is during disk writes, for example if I open and close an empty file in gedit it can ...
3
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1answer
175 views

Turning off power to usb port. Or turn off power to entire usb subsystem

I have a usb lamp which I specifically bought in order to turn it off programmatically at a certain time, thus I need to remove the power to its usb port. I believe I have a usb-hub at usb6. The lamp ...
1
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0answers
28 views

can't filter printk messages

I'm writing a driver and usually I implement my own log-level scheme. However, this time I figured that I would try to utilize the printk scheme that is built into Linux. I see that I can adjust the ...
0
votes
0answers
13 views

How does setting the PE flag in CR0 enable protected mode? [migrated]

I am trying to understand how a machine goes from power on to running a kernel. From what I've gathered, it is useful to switch into protected mode during boot up in order to gain access to more ...
2
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0answers
31 views

Where is located syscall_table in kernel x86_64? [migrated]

I'm trying to add new System Call to Linux Kernel(x86_64). Based on this article which explained how to add System Call to Kernel(x86). The article says I need to define my System Call name in a file ...
1
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0answers
32 views

open() sys call [closed]

Process A wants to open a file fd1 = open("/var/file1", O_RDONLY); In the process of opening file1 which table is referred first system wide file table or file descriptor table or in-core inode ...
0
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0answers
20 views

How can I compile and run a program designed for an older kernel version (2.6) in a newer kernel (3.16)?

I'm trying to run a driver for a network card, but it only supports kernels up to 2.6.32. I need to be able to use this piece of hardware to connect to the Internet. The device I'm using is "VIA ...
0
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0answers
156 views

FreeBSD boot problem, UEFI or LEGACY and GPT disk

i have a computer based on GPT disks with triple boot. For the moment i have two OSes working on my computer (OSX and Windows). I want to make a FreeBSD installation, he work perfectly when i boot on ...
16
votes
3answers
154 views

How did the Linux Kernel project track bugs in the Early Days?

We all know that Linus Torvalds created Git because of issues with Bitkeeper. What is not known (at least to me) is, how were issues/tickets/bugs tracked up until then? I tried but didn't get anything ...
1
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2answers
50 views

Which function in Linux kernel do the powering off action?

I am not asking how to shut down. I am asking how to cut of the power. What is the function in Linux kernel code do the action of cutting of the power? And please explain the code.
1
vote
1answer
20 views

What directory houses the scripts that get executed with new kernel installations?

This one is pretty much a straightfoward question/answer I just can't locate the information. I'm trying to automate the re-installation of VMWare tools based off when a new kernel is installed. I ...
0
votes
0answers
18 views

RHEL 6.5 erroneously marking Fusion-io RAID1 card as failed

I am getting the following error every hour for a Fusion-io ioscale2 RAID1 (mirror) configuration. However, the logical volume is mounted and accessible. I do not see similar error in the ...
0
votes
1answer
42 views

How can I boot into Ubuntu with a linux kernel with an earlier version?

Part of the output of ls -ld /usr/src/linux-headers* on ubuntu 12.04 is: drwxr-xr-x 24 root root 4096 Jun 4 2013 /usr/src/linux-headers-3.2.0-45 drwxr-xr-x 7 root root 4096 Jun 4 2013 ...
1
vote
0answers
21 views

How/where are linux device capabilities / bitfields set?

I have a device that has this output in /proc/bus/input/devices: I: Bus=0003 Vendor=05b8 Product=3280 Version=0111 N: Name="PixArt USB Optical Mouse" P: Phys=usb-0000:00:1a.0-1.1/input0 S: ...
0
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0answers
20 views

How do I set kernel-ml default in CentOS?

I have installed kernel-ml package from http://elrepo.org/tiki/kernel-ml Now I have both the original CentOS kernel and kernel-ml. How do I set kernel-ml as default on boot? Thank you!
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0answers
65 views

iwlwifi: timeout delays firmware to be loaded

I'm using OpenSuSE 13.2 beta (which runs by the way very nicely). When starting up, my wireless adapter (Intel Centrino Ultimate-N 6300 AGN/Thinkpad T420) delays about one minute... But then it works ...
0
votes
1answer
114 views

yum update returns kernel error

I want to install virtualbox in fedora20. I have followed the instruction here: http://www.if-not-true-then-false.com/2010/install-virtualbox-with-yum-on-fedora-centos-red-hat-rhel/ but when I ...
0
votes
1answer
37 views

How can I check if a certain patch is already installed in my system?

I am about to install a patch for wireless drivers named Compat Wireless in order to solve a problem with my WiFi channel (it locks on the not existing -1 channel) on my Ubuntu Linux v12.04 and Kali ...
0
votes
1answer
94 views

IPTABLES comment: No chain/target/match by that name

Faced with error when adding new rule with 'comment': # iptables -I INPUT 1 --source 66.***.***.78 -j REJECT -m comment --comment "Some" iptables: No chain/target/match by that name. Without ...
0
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0answers
30 views

Surface Pro Compatible Wireless cards and drivers

In reference to this post: Surface Pro Wifi Issues on Mint KDE 17 there doesn't seem to be any solution to fixing the wifi issues on the Surface Pro when running Linux. The Marvell card doesn't even ...
2
votes
1answer
71 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 ...
0
votes
3answers
50 views

Linux Distro name API to get name of linux distro in a driver code?

I am writing a common code in a driver to get the distros name and host name. host name i am taking from struct utsname{nodename[]}, but how do I get the distro name?
2
votes
1answer
66 views

How to change the kernel max PID number? [duplicate]

The default PID max number is 32768. To get this information type: cat /proc/sys/kernel/pid_max 32768 or sysctl kernel.pid_max kernel.pid_max = 32768 Now, I want to change this number... but I ...
0
votes
1answer
70 views

Role of the Intel P state driver

I searched high and low for what “Intel P state” is and what it does. I found out that it has to do with performance and power consumption. I learned that if you build it in the kernel, it'll becomes ...
0
votes
0answers
40 views

How to display printk messages filtered by level as they come?

I wrote a hello word module that performs a printk when it is loaded in level ALERT and another printk when it is released with level INFO: #include <linux/module.h> #include ...
13
votes
3answers
214 views

How to force Linux kernel to “freeze” (or nearly freeze) for a few hundred milliseconds

We are running a real-time process on a non real-time kernel (CentOS 6), and this is probably not going to change. We have a streaming video application that requires about 500 MB/s of PCIe traffic ...
0
votes
0answers
33 views

Best approach to adding a kernel driver

I have a task to complete. An LED must be controlled immediately after the kernel loads and into the launch of a Debian system. It also must be controlled in user land. I already have basic LED ...
2
votes
1answer
35 views

What does kernel-wedge do?

After looking at the package description and using kernel-wedge help, I'm not really sure what it does. Does it take a .deb kernel package and split it into smaller packages? Does it compile a ...
0
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0answers
21 views

How to recompile official OpenSUSE kernel & initrd?

But it is not okay. I want all of the suse patches applied, I want an official initrd to be generated, and I want to make rpms from all of them. So, I want to recompile the kernel just as the SuSE ...
2
votes
0answers
60 views

Explanation of the building process of the kernel on Ubuntu/Debian systems

I'm getting into Linux kernel programming and I have successfully built my own kernel several times now. However, I have done it using step by step guides found from the internet and I don't really ...
0
votes
0answers
50 views

Fedora 20 won't startup after shutdown during kernel update

I had a few bugs in my System(System Settings not opening and Firefox not starting) and I thought a kernel update(via yum) could do it some good. During that update, I suddenly got logged out as if ...
1
vote
1answer
99 views

Full UEFI System, Grub 2 self-compiled + Clover 2, Debian kFreeBSD installation?

I've a computer with full installation UEFI system, with 2 bootloaders (GRUB & Clover on ESP) clover is the primary bootloader that allows me to load OSX and grub2. I want to make a new install of ...
0
votes
2answers
51 views

Compilation error when building a custom kernel

I'm trying to build a custom kernel from a git repository on my Ubuntu virtual machine. I run the make command as follows : sudo apt-get install vim libncurses5-dev gcc make git exuberant-ctags mkdir ...
1
vote
1answer
38 views

Binding to not existing interface

I've just noticed the very weird situation I don't have a good explanation for. The machine (debian) has one interface with one IP address assigned: # ifconfig vmbr0 |grep inet inet ...