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

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Why does Linux have poor battery life by default compared to Windows?

Is there something inherent to Linux operating systems that makes them poor managers of battery power by default? I would have thought a light distro like Lubuntu would have a clear battery life ...
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0answers
54 views

Where is Linux kernel development headed? [closed]

I regularly read development updates from various components of the Linux ecosystem. Of all these, the kernel is the one that seems least transparent to me. Typical kernel release notes mention tons ...
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1answer
211 views

Kernel /proc ipv6 settings precedence

I'm about to connect our network to the IPv6 Internet and need to control the kernel ipv6 settings found under /proc. I know there are configurations for each interface, for all interfaces, and the ...
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2answers
714 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
80 views

What is CONFIG_BASE_SMALL=0

Looking at the config file of Linux (that is generated prior to build) I found the following line: CONFIG_BASE_SMALL=0 What does it mean? If I want my linux kernel to be as small as possible shall ...
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0answers
105 views

Looking for a list of modules that are used during boot sequence

I'd like to use deferred init calls. This function allows to load modules in userland, that should actually be loaded during the boot sequence. Just for testing I'd like to modularize as many entries ...
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93 views

How to cause memory fragmentation on a Linux based embedded device?

Hardware ARM What am I trying to do: Answer: I am trying to create memory fragmentation on a Linux 2.6.31 based swapless embedded device. Why: Answer:I am trying to port some patches to Linux ...
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2answers
1k views

BSD Kernel Vs. Linux kernel? [closed]

I wanted to know in technical terms; what is the difference between BSD Kernel and Linux Kernel. In Linux, we can download the source kernel then patch it and make and make modules it. Even we have ...
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1answer
318 views

Linux: What is a tainted kernel?

Under certain conditions, the Linux kernel may become tainted. For example, loading a proprietary video driver into the kernel taints the kernel. This condition may be visible in system logs, kernel ...
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Why there are many BSD systems but only one Linux kernel?

Why there are many BSD systems but only one Linux kernel? I wonder why BSD was forked many times, but no such thing with Linux.
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1answer
562 views

Try to disable console output, console=null doesn't work

as mentioned above, I want to to completely turn off the console output, but putting console= or console=null in the kernel command line doesn't change a thing. When I enque quiet to the kernel ...
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1answer
99 views

How to relate a kernel config setting to the source files?

Here is an example that will explain better: I have a selected the audio driver from the picture and i would like to browse through its source. How do i get to the path of the source files from ...
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1answer
51 views

Does perf includes some “graphing” abilities?

It's possible to create a bitmap or a vector image out of the data collected by the perf profiler under linux ?
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550 views

“select” vs “depends” in kernel Kconfig

What are the differences in dependencies between select and depends on in the kernels Kconfig files? config FB_CIRRUS tristate "Cirrus Logic support" depends on FB && (ZORRO || PCI) select ...
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1answer
109 views

Compiling Linux kernel for a router [closed]

I want to make an installable linux kernel that has routing enabled already. So anyone can install it on their machine, do some configuration as required, and machine will work fine for their routing ...
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2answers
389 views

Kernel Configuration: Which Processor Family to choose for 'Celeron M CPU 420' (Core Solo)?

I am trying to build custom kernel (version 3.12.13) for my old laptop and I am unable to determine the Processor Family from the provided list. ( ) 486 ( ) 586/K5/5x86/6x86/6x86MX ( ) ...
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0answers
59 views

Why does the kernel boot faster with less memory allocated?

This is not a important question, I'm just curious. Something strange happened, which isn't quiet clear to me: In the kernel command line, the amount of the memory can be set statically with the ...
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0answers
41 views

What are the linux kernel versions incompatibilities with btrfs?

I read that usage of a btrfs volume with a newer kernel can render it unreadable when that same volume is used with an older kernel. I have a mobile storage device that will be used by different linux ...
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3answers
62 views

Structure of GNU/Linux [closed]

I have some basic knowledge about Linux OS like it consist of Kernel.The kernel is core of Linux , It manages all processes, device drivers, and I/O.But My Question is what Linux consists of beside ...
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2answers
66 views

CentOS 6 with Linux-Libre kernel?

I understand that CentOS ships with nonfree blobs in it's kernel. It seems that a "nonfree blob" free kernel exists, a.k.a. Linux-Libre. Is it possible to somehow get CentOS to use Linux-Libre ...
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0answers
104 views

KMS Terminal: How to disable second screen, or how to force a certaion resolution?

I have two screens with different native resolution connected to my Gentoo/systemd machine. since the VTs try to mirror the outputs, they do not use the whole size of the higher resolution screen. I ...
2
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1answer
307 views

Virtualbox complains that I don't have headers

I've installed Virtualbox (on Debian testing amd64)according to the wiki. But I get this error: $ virtualbox WARNING: The character device /dev/vboxdrv does not exist. Please install the ...
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1answer
103 views

Debian/Ubuntu:How to compile a Linux kernel on one machine and use on other machines (same architecture)

Debian/Ubuntu: How to compile a Linux kernel on one machine and use on other machines (same architecture)? I know how to do it on the same machine. But to use a compiled kernel other machines, is ...
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1answer
147 views

Which Linux distributions offer a stable release based on the 3.10 kernel?

I'm looking for a stable Linux distribution (preferably a well-known one) based on the 3.10 kernel. So far I have identified Gentoo as one such distribution. But I'm having trouble finding any others. ...
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32 views

Patching the kernel source through git

I'm trying to understand how the patching of the kernel source works. I found the patch that I would like to try an apply on the following page. I found no .patch files that I can use to apply the ...
7
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1answer
194 views

Why are cgroups mapped differently on these two systems by systemd

I have two systems, both running customized variants of OpenSuSE 12.2 (Mantis), both running exactly the same kernel. I get two very different outputs of /proc/self/cgroup or /proc/$$/cgroup on the ...
2
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1answer
68 views

How much time do user => kernel mode transitions take?

I'm running Android-on-Linux, and communication of OpenGL ES calls over the QEMU pipe is very slow. QEMU pipes should be the fastest possible way to do this; could this be due to the repeated ...
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1answer
41 views

Getting correct perf version

I'm trying to run perf on my Ubuntu Precise box, which I recently upgraded to kernel 3.11.10-03111002 (manual install). The problem is that perf and kernel versions must match, and the requested ...
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1answer
163 views

Kernel 3.13 on Ubuntu ARM + Android kernel options compatibility

I've installed ubuntu 12.04 LTS with the kernel 3.13 on my ARM Samsung / Google Chromebook,using this tutorial : http://www.virtualopensystems.com/en/solutions/guides/kvm-on-chromebook/ I have to ...
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3answers
195 views

Why does boot from SD card with my custom kernel result in “VFS: Cannot open root device”?

I'm using an embedded board ARM9 SAM9G25. I want to boot from SD card. When I build a linux kernel with a built-in rootfs (initramfs) then it boots. I want to separate the kernel from rootfs and I ...
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kernel: “echo 0 > /proc/sys/kernel/hung_task_timeout_secs”

I got this errors in syslog. Any idea what does it mean? The system is running on Ubuntu 12.04, kernel: 3.8.0-35-generic #52~precise1 It looks to me like failure when trying to write to disk... ...
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1answer
106 views

Having difficulties mounting a rootfs for an embedded Linux

I want my Kernel to start a squashfs rootfs for an embedded Linux. The squashfs file is on a sdcard, therefor i put these parameters on it's command line: console=ttyS0,115200 root=/dev/sdb1 rw ...
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1answer
109 views

Does using noatime on modern Linux make sense?

Starting from version 2.6.30 (which was released 5 years ago), Linux has the option relatime enabled by default. It means updates of file access time are very infrequent and prudent. But I still see ...
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What is the difference between a patch which reverts a commit and a “reversed patch”?

Before May 6th, 2013, the fs/eventpoll.c file in the Linux kernel had the following line #1605: if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS)) On May 6th, a commit changes this to ...
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1answer
66 views

What is not accessible from userspace?

I read somewhere (3.1.3) that there's a high ring (supervisor mode) and a low ring (user mode) and that some "things" can be run only from the highest ring. What do they mean by "things"? I'd guess ...
4
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1answer
845 views

“Memory corruption detected in low memory” kernel messages?

I have some memory corruption detected in low memory messages. I have read about it here, but I'm afraid I can't really make anything out of the discussion. It does indeed happen when I ...
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1answer
80 views

How long do dentries stay in the dcache?

On Linux, when I create a new file and open it, an entry about it is created in the dcache's hash table, right? How long does that entry stay there? Does it get removed when nothing is currently using ...
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2answers
125 views

ck patch for Linux 3.13 [closed]

Does anyone have any news about the -ck patches for Linux 3.13 kernel tree? I've checked here but there's nothing yet...
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1answer
50 views

RHEL6: Failed Dependencies when installing a package

Hi I'm getting errors when forcing to install unixODBC package on RHEL 6 here is the following error: http://flic.kr/p/jBEFvP I don't know where to get the following packages that were needed by the ...
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0answers
126 views

Issue with Hugepage reservation in linux

I have reserved hugepages for my process using below commands: #echo 64 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages #mkdir -p /mnt/huge && mount -t hugetlbfs nodev /mnt/huge ...
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0answers
50 views

Recommendation for kernel config UEVENT_HELPER_PATH?

I use Gentoo Linux. Historically the kernel configuration UEVENT_HELPER_PATH to hotplug, then later to udevadm. Mine has been set to /path/to/udevadm, but I've had problems in the past on Gentoo ...
3
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1answer
76 views

Embedded Linux: Which machine directory to pick in /arch/arm?

I am just starting out with embedded Android drivers, so any help would be great. I haven't found a lot of resources online. At the moment, I am working through a tutorial on porting a driver, and ...
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1answer
2k views

What do the kernel parameters acpi_osi=linux and acpi_backlight=vendor do?

I had troubles with the screen brightness control in my laptop and I fixed it by adding the acpi_osi=linux and acpi_backlight=vendorparameters to the filegrub.cfg. I'd like to know what these ...
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2answers
91 views

why do I need to patch linux kernel to use pandaboard's spi?

I believe this question is a bit more general but here is how it goes : I have read this article about using pandaboard's SPI, especially the part "Configuring and patching the kernel". It says that ...
1
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1answer
242 views

Resolving executable user stack trace addresses in ftrace

I'm trying to obtain a user stack trace in ftrace, but for some reason, only my user program cannot resolve the addresses to symbols. First, the OS I'm using is: $ uname -a Linux mypc ...
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2answers
748 views

Observing a hard-disk write in kernel space (with drivers/modules)

Apologies in advance if this post is a bit dense/messy, but I'm having a hard time formulating it better... Basically, I would like to study what happens upon a hard disk write, and I'd like to know: ...
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2answers
239 views

In a UID namespace, can I setuid to an unmapped UID?

Suppose I'm user ID 1000. I run a program inside a UID namespace, mapping UID 0 inside the namespace to UID 1000 outside the namespace. The program then attempts to change its own UID to 50, which ...
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1answer
716 views

How to fix make error “No rule to make target 'menuconfig'” when building a kernel for Beagleboard?

The aim is to build and install the USB Video Class (UVC) module, via make modules_install. I'm trying to configure the kernel via make menuconfig on Angstrom distribution, running on BeagleBoard-xM. ...
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1answer
125 views

Change the root filesystem on an embedded system

I'm using Buildroot to generate an embedded Linux with a kernel v. 2.6.39, which in the end starts busybox. Everything works fine when building with Initramfs as "rootfs". But Initramfs isn't the best ...
4
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1answer
109 views

Why do the data and code segments completely overlap in Linux?

Context: I'm reading "Understanding the Linux kernel, 3d ed", which uses the 2.6.11 kernel. Question: As I understand, the physical address is obtained by translating the linear address, which is ...