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

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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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63 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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55 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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113 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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53 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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28 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
57 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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39 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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38 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 ...
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1answer
75 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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56 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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79 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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20 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 ...
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73 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 ...
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1answer
37 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
27 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
93 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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1answer
65 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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579 views

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
56 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
55 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
47 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 ...
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223 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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36 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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118 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
22 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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26 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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21 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 ...
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1answer
52 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
703 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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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 ...
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1answer
95 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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504 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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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
165 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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89 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 ...
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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 ...
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Why does the Linux kernel report “out of disk space” when in reality it is out of i-nodes

A friend of mine who likes programming in the Linux environment, but doesn't know much about the administration of Linux recently ran into a problem where his OS (Ubuntu) was reporting "out of disk ...
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1answer
92 views

How to build a basic embedded linux on a Qualcomm router?

Not knowing the first thing on how to build a minimal linux system on an embedded device, I'd like to get some pointers in the right direction. Generally speaking, I'd like to know what are the ...
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1answer
99 views

moving from user mode to kernel mode

I read the following: "All processes begin execution in user mode, and they switch to kernel mode only when obtaining a service provided by the kernel." When it says "obtaining a service ...
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102 views

Compiling Linux and Creating Bootable ISO Image

I have already compiled Linux kernel 3.12.6 but did not install it into /boot as I did not want my hard disk to have another OS. I have the compiled bzImage and I don't know how to take that and ...
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1answer
34 views

Make Install Linux Kernel Location Change

I have already run make to compile the Linux Kernel 3.12.6, but when I run make install, I don't want it to install it in /boot (as I don't want another OS on the hard disk). How can I change it so it ...
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5answers
167 views

On executable files in Linux [closed]

It is said that in linux, unlike Windows, there's not a clear border between executables and other files. Well, in Windows, I write a C++ program, then it is precompiled, compiled and then linked to ...
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120 views

GRE supported in kernel but iproute2 cant create GRE tunnel

Im trying to create IP over GRE tunnel but i get No such device: ip tunnel add gre0 mode gre remote 192.168.152.22 local 192.168.152.21 ttl 255 ioctl: No such device I have compiled GRE support in ...
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LVM RAID 1 for root

I have LVM RAID 1 (not mdadm RAID 1, but exactly LVM2 RAID 1) for my root partition. I would like to make my system boot without either of the HDDs where the underlying PVs of the root LVM partition ...
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SELinux and Trusted OS - can SELinux be confined to hardware level root?

I am exploring on SE Linux and while doing so i found it as an example of Trusted OS. Is it really an example of Trusted OS stack like TrouSerS ? SELinux as per my understanding modifies the Linux ...
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1answer
116 views

No usable clock interface found

I just finished installing a paravirtualized archlinux guest on xen. I get the following error when my guest boots: [1.185226] i8042: No controller found [1.1247134] drivers/rtc/hctosys.c: ...
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1answer
98 views

Is there a command to switch to into an existing namespace?

I am using multiple UTS namespaces, each of them has some servers constantly running. I can get the namespace IDs via readlink /proc/<pid>/ns/uts, now I would like to change into a given ...
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136 views

how do I include the qcserial module in the kernel?

I need a kernel compiled, featuring the qcserial module to have support for the Huawei EM 680 model (Gobi 3000). I got kernel 3.11.6 and can find the appropriate source file in ...