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

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3answers
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how to monitor a unix directory and if any new file in directory it will be copied to another directory

I want to monitor a unix(Solaris 10) directory and if there is any new file i want to copy immediately. Tried: I have shown inotifywait and incron package in linux for it but i don't know whether it ...
3
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1answer
64 views

Does the O_DIRECT flag bypass the Linux page cache when accessing block devices too?

I am running a lot of KVM virtual machines, which open the hard disk image with the O_DIRECT flag. I understand, according to the open() man page, that using O_DIRECT will try to bypass the Linux ...
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0answers
40 views

Dereferencing string pointer in ftrace event filter

I'm currently trying to create an ftrace event filter for the event sys_enter_open which is filtering by the filename argument. Looking at the format definition of it I can see there's a filename ...
0
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1answer
54 views

make + bash: setting environment variables on command line doesn't work

I am trying to build the kernel for Raspberry-pi on my Debian-8 host machine. I passed the following commands to build the kernel make ARCH=arm KERNEL=kernel CROSS_COMPILE=arm-liux-gnueabihf- ...
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1answer
141 views

Linux not using all memory

I have a PC with Fedora 23 OS with 4 GB RAM, but usable memory is 2 GB. When I tried to check memory: # dmesg | grep Memory [ 0.000000] Memory: 1753008K/1816676K available (7670K kernel code, ...
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2answers
85 views

Booting stops at Loading initial ramdisk

I have installed Arch Linux on 40GB HDD on ga-g4mt-s2p1 Motherboard ( Intel Core 2 multi-core,2Gb of Ram) I have made 4 Partitions: /boot 100Mib Swap 4Gib / 20Gib /home The rest of the disk It ...
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0answers
16 views

init & System V IPC in kernel

Does it affect init if System V IPC is not compiled into a kernel? Does init require System V IPC?
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62 views

Add a module to linux kernel source code statically [closed]

I am new to linux kernel programming. I have explored that there are two ways of adding modules to linux. One way is by dynamically linking the modules with the running kernel using insmod and another ...
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0answers
27 views

Why are there no LSM hooks in the POSIX IPC APIs?

As I understand it, the Linux Security Module (LSM) framework has many hooks which are callbacks for security modules to register functions performing additional security checks before security-...
4
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1answer
70 views

Can the kernel symbols' addresses be influenced? consequences?

tl;dr: in my distros linux 3.08 kernel using cat /proc/kallsyms I can find out that for instance the _commit_creds function/symbol is located at address 0xc1073fe0. When either: building my kernel (...
4
votes
1answer
155 views

how to eject/unmount usb dongle logically?

We've bought a commercial application who just work only if their dongle usb is connected to the server. However sometimes the application can not recognize the dongle, so it doesn't work, but if ...
2
votes
1answer
59 views

Why does Linux have a maximum number of sound cards? [closed]

I'm specifically asking about CONFIG_SND_MAX_CARDS in the kernel. From the code using this config, for example in sound/usb/card.c for USB cards, soundcards are stored in plain arrays which are ...
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0answers
61 views

Linux kernel running only with use of physical address

Is it theoretically possible to make Linux which for its own kernel (include modules) uses only physical addresses? (it means it completely omits MMU) For processes how would you know if there was ...
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0answers
20 views

Changing the Retransmisson Timeout (RTO) estimation in Fedora

Retransmission Timeout(RTO) in a TCP plays a vital role in the internet. There are many algorithms proposed for calculating the Retransmission timeout. RFC 6298 is used for the estimation of RTO. I ...
2
votes
1answer
410 views

256 colors in console (tty)

Suppose, I have a system without X server. I can only log in from the console. It seems, by default linux console supports only 8 colors: # tput colors 8 Is it possible to use 256 colors in the ...
0
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0answers
62 views

Need help determining why a usb device works in Ubuntu but not ChromeOS

I am troubleshooting a problem with an Epson Brightlight 536wi projector. When you plug a USB cable from the projector into a Windows or Linux computer there is a driver built-in to both Operating ...
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0answers
56 views

OpenWRT image for OrangePi

I am looking for help on how to build OpenWRT image for OrangePi PC and|or OrangePi Plus board, preferably with working Ethernet and HDMI. I have studied related resources on the internet, like ...
0
votes
1answer
132 views

compatiblity with Intel Dual Band Wireless-N 7260 (on tablet)

I hold a Dell Venue Pro 11 7130 with the following integrated network adapter: Intel Dual Band Wireless-N 7260. My aim is using Linux in live mode on it. Most of the distros I've being running so ...
3
votes
4answers
444 views

Restrict size of buffer cache in Linux

Is there a way to tell the Linux kernel to only use a certain percentage of memory for the buffer cache? I know /proc/sys/vm/drop_caches can be used to clear the cache temporarily, but is there any ...
0
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0answers
39 views

WARNING: at net/ipv4/tcp.c:1654 tcp_recvmsg

Our Linux based device (3.7.2) experiencing following issue when we try to do FTP or SCP over WiFi Connection. Same will work on Ethernet Connection or on TFTP. Here is the dmesg log for this issue: ...
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0answers
18 views

DMA address mapping with physical memory

i need to physical RAM memory test, in that case i dont want to check DMA pages,how to find out DMA pages.how its allocated in physical ram ? if it is allocated in physical RAM. Testing RAm then i ...
1
vote
1answer
123 views

What does 'make localmodconfig' do?

What does make localmodconfig do and what should you set so that external hardware is supported?
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0answers
16 views

Autoloading a particular driver, based on a detected specific kernel

I need some help in writing a tiny script and determining its placement within Debian 7.9 filesystem. As the title says, the script needs to be executed automatically on startup and, after checking ...
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0answers
40 views

Building Linux driver for a network card remotely, while being connected via the same card

I realize that the title alone sounds confusing, so let me provide the context. My current Linux machine configuration is Debian 7.9 (I need this specific version) with the default kernel 3.2, which ...
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1answer
148 views

find which process is sending the current io request in linux kernel

I've been diving into the Linux kernel. and would like to trace an io request and find out exactly which process sent the current io request? There is a structure named current which the kernel ...
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1answer
25 views

adding a governor

how to add the Governor in the appropriate spot..they said"Add the following lines in appropriate spot amongst the other govenor's" Yes, they've given one code that i have to add, but how ? here is ...
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50 views

Linux Kernel is panicing on boot

After following this blog post I get a kernel panic when running: qemu-system-x86_64 -kernel bzImage -hda my.img -append=/dev/sda What could be causing this? Could I have left something out?
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1answer
938 views

“rcu_preempt detected stalls on CPUs / tasks” message appears to continue

My board continues to display the message below. The terminal does not have any input. What is it with the following message, which I know? (T, g, c, q ...) What is the cause of this phenomenon? ...
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0answers
58 views

Compiling a single kernel module which resides in the kernel tree

I have updated my Linux kernel to 4.3.3, everything works smooth except my webcam (QuickCam® Pro 9000) which is not working. According to the dmesg, the kernel recognizes the I have plugged a usb but ...
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0answers
46 views

How async_port_probe() call works in linux kernel?

To Understand the SATA device enumeration process I was studying the driver/ata/ata_piix.c which is showing as SATA host driver for my system in the output of lspci command. 00:1f.2 IDE interface: ...
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1answer
38 views

where is make_request_fn source code in linux kernel

in my study and examine linux kernel code I encountered with function make_request_fn. in this link it says that this function type definition is in include/linux/blkdev.h, line 211 : typedef void (...
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0answers
37 views

What is txqueuelen equivalent for receiving in linux?

I have always wondered that txqueuelen in output of ifconfig command defines transmission queue length in linux in terms of packets which I assume get utilized in various qdisc management while ...
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213 views

Linux Kernel module Remote Debugging with GDB + KGDB, Remote 'g' packet reply is too long

I am trying to remotely debug Linux Kernel and I am having issues. My setup: Target machine with Ubnutu Linux with my custom kernel 4.3 which I built with debugging information and KGDB. ...
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58 views

printk does not prints in terminal

I inserted some printk in kernel 3.15.1 functions such as theese: in fs/read_write.c in function read(): printk("Ata: Im in fs/read_write.c and in function read"); in same file in function ...
3
votes
1answer
107 views

Creation of the heap region/segment in Linux

It's my understanding that on Linux the process loader doesn't automatically create a "heap" region for a process like it's the case for the stack, is that correct? I used /proc/$$/maps and before ...
30
votes
1answer
1k views

What is a “subreaper” process?

The word "subreaper" is used in some answers. Searching Google also turn up entries where the word is "just used". How can I understand what a "subreaper" is?
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1answer
30 views

which section of kernel, manages io requests?

I know that the Block IO layer in Linux io stack manages and schedules io requests. but i do not know where is this code? indeed, i wanna see the section of code in kernel which corresponds to this ...
4
votes
2answers
85 views

In which thread does block driver issue commands to block device?

I'm currently reading "Understanding The Linux Kernel" book, as I've understood block I/O request order is like this; user space call => vfs call => I/O scheduler call => block device driver call. ...
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1answer
151 views

How to find the driver (module) associated with SATA device on Linux?

For one of my applications, I have to understand the the SATA device driver flow. As per my understanding, SATA device driver should be there in the Linux kernel tree. I have referred how to find the ...
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0answers
14 views

last samples are skipping when we do record and playback in loop back mode in linux

I am just connecting my output to the input of codec using mixer controls in linux. I am recording the data with tinycap in bag round and then I started playing of a 30 seconds sine tone using ...
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0answers
177 views

Linux 4.3 - Waiting for root device /dev/mmcblk0p1

I want to update my custom i.MX6 Board to Linux 4.3, but with the new Kernel the boot process stops at boot and can't load the rootfs from sd-card. With the old Kernel 4.1.x it works fine with the ...
1
vote
1answer
144 views

Porting Linux on LPC2148 board

Till now I was working with Raspberry pi, beaglebone etc. So, I am looking to do something new. So, I decide to port Linux on my LPC2148 board. But I am unable to find any tutorial regarding linux ...
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0answers
194 views

Create CentOS-7.1 custom iso with upgraded kernel-4.2.6

I am trying to create CentOS-7.1 custom ISO with kernel-4.2.6. But I am facing issues while installing. Please see attached image for details. I have followed the following steps to prepare a custom ...
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1answer
31 views

Kernel module version enforcement

Linux can be configured to require that kernel modules be digitally signed. On kernels built for embedded devices and consumer devices (i.e., tablets, smartphones, etc.), I can still see that this ...
2
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0answers
39 views

how to build kernel-tools-4.2.xx.rpm and kernel-ltools-libs-4.2.xx.rpm

I am trying to upgrade Centos-7 kernel (kernel-3.10) to (Kernel-4.2.6) and for that I downloaded kernel from kernel.org and create rpm for the custom configuration (arch x86_64)using "make rpm". ...
0
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1answer
24 views

Linux tools for perf (install linux-tools-3.15.0)

I use Linaro version of Linux (Linaro 12.11) on my embedded target with ARM9 Core. For a certain profiling, I need to use the perf tool. perf require linux-tools-3.15.0 to be installed on my device. ...
2
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1answer
1k views

Intel Skylake + DisplayPort 1.2 MST/Daisy chain on Linux

I am planning to buy hardware for using DisplayPort 1.2's MST feature to daisy chain two monitors in combination with the Intel Core i5 6600 Skylake processor on Ubuntu. Is this supported yet with the ...
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vote
1answer
120 views

DKMS modules never installed properly on kernel upgrade

I have multiple DKMS modules installed on my system, some of them mine, and some of them belonging to pretty major maintained packages such as Oracle's VirtualBox 5. What I've found is that on every ...
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0answers
172 views

Remapping Apple Keyboard with Linux Mint

I like to use an apple wireless keyboard with my laptop that runs Linux Mint 17.2 Cinnamon 2.6.13 64-bit with the 3.16.0-38-generic kernel. However, I would like to remap the fn, alt, command, control ...
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1answer
119 views

Running a real time kernel on Debian

As I have Debian 8 running on my laptop, I have got some questions about making my OS a Real-Time one: Does the Debian GNU/Linux distribution have an official Real-Time version? (I found that the OS ...