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

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3answers
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Ping IP works, nslookup fails. New Kernel

I am compiling my own 3.14 kernel. I fear I may have left out some important networking feature to get DNS working. I can't resolve domain names. I can ping my DNS server. I can resolve using that ...
23
votes
4answers
30k views

disable transparent hugepages

We are installing SAP HANA in a RAID machine. As part of the installation step, it is mentioned that, To disable the usage of transparent hugepages set the kernel settings at runtime with echo ...
3
votes
3answers
3k views

How to add more /dev/loop* devices on Fedora 19

How to add more /dev/loop* devices on Fedora 19? I do: # uname -r 3.11.2-201.fc19.x86_64 # lsmod |grep loop # ls /dev/loop* /dev/loop0 /dev/loop1 /dev/loop2 /dev/loop3 /dev/loop4 /dev/loop5 ...
0
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0answers
15 views

High read/write system call time

I am facing a weird problem with one of process taking more processing time in one system comparing to other systems. Most of the time is spending on read and write system call on problem host. I am ...
1
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2answers
33 views

Triggering hardware interrupts by connecting parallel port pins 9 and 10 does not work

I want to trigger hardware interrupts as described in the book Linux Device Drivers by connecting pins 9 and 10 with a wire. I tried that but apparently there's no interrupt beeing triggered: cat ...
1
vote
1answer
2k views

Driver install, kernel source not found

I am trying to install a NVidia Cuda driver on a Amazon EC2. GPU instance (Amazon Linux AMI (HVM) 2013.09.2 - ami-e9a18d80) following the instructions laid out in a blog. It worked for the last two ...
4
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2answers
899 views

Benefiting of sched_autogroup_enabled on the desktop

I am running a 2.6.37 kernel with sched_autogroup_enabled set to 1. I am not certain that I am seeing the benefits of this patch since: I am launching my applications from the desktop; applications ...
0
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1answer
485 views

custom kernel and firmware loading

After I have compiled my kernel, and when I type make modules_install, not only are the modules copied into /lib/modules/ but also firmware is copied into /lib/firmware/. The following is the end of ...
6
votes
1answer
4k views

“Argument list too long”: How do I deal with it, without changing my command?

When I run a command like ls */*/*/*/*.jpg, I get the error -bash: /bin/ls: Argument list too long I know why this happens: it is because there is a kernel limit on the amount of space for ...
3
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0answers
30 views

Book for understanding latest Linux kernel [closed]

I want to understand the Linux kernel. For this I have the book "UnderStanding the Linux Kernel, 3e". Inside the book I have found that the book has written based on Linux kernel 2.6. But as my ...
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0answers
7 views

Sequential process execution? [closed]

How do I create multiple processes and run them in a certain sequence? The scheduler should not switch context. I am running a set of at least hundred programmes which must repeat after sometime while ...
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votes
2answers
1k views

busybox initramfs loop mount

I'm trying to loop mount my root filesystem (a loop file) within a busybox initramfs. I try to run the command: mount /rootfs.raw /root ... which works on my Ubuntu laptop, however, I simply get ...
0
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2answers
695 views

How to disable core dump generation in Centos (cPanel Server)?

I want to disable core dump generation, How can I disable it ? One of the website keeps generating core dumps every second and eats up all the disk space. OS Details: CentOs cPanel Server ...
3
votes
2answers
169 views

What are the programs/commands which the magic SysRq key invoke?

From Magic SysRq key The magic SysRq key is a key combination understood by the Linux kernel, which allows the user to perform various low level commands regardless of the system's state. It ...
-1
votes
1answer
34 views

How do you install the FreeBSD10 kernel sources?

I am trying to run an update of freebsd10 and I am being asked for the kernel sources ===>>> Launching child to update lsof-4.89.b,8 to lsof-4.89.d,8 ===>>> All >> ...
5
votes
2answers
709 views

Compiling the kernel with default configurations

Assumptions: The platform: anisha@linux-dopx:~/> uname -a Linux linux-dopx 2.6.34-12-desktop #1 SMP PREEMPT 2010-06-29 02:39:08 +0200 x86_64 x86_64 x86_64 GNU/Linux The kernel downloaded is the ...
5
votes
4answers
4k views

Prevent claiming of novelty usb device by usbhid so I can control it with libusb?

I have a USB rocket launcher that I wish to experiment with through libusb. However, libusb cannot claim the interface; presumably because the output of usb-devices lists 'usbhid' as the driver for ...
1
vote
1answer
32 views

Where is routing table stored internally in the Linux kernel?

When I execute route -n, from where exactly (from which structs) is the information displayed retrieved? I tried executing strace route -n but I didn't help me finding the right place it's stored.
32
votes
7answers
21k views

Linux Kernel: Good beginners' tutorial [closed]

I'm interested in modifying the kernel internals, applying patches, handling device drivers and modules, for my own personal fun. Is there a comprehensive resource for kernel hacking, intended for ...
1
vote
0answers
10 views

Why there is PPPd instead of all PPP software in kernel?

Are there any reasons why the need of PPP software separation from kernel and process (PPPd)?
2
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3answers
2k views

Linux freezing guess: keyboard & mouse (Archlinux and Ubuntu)

Linux on my PC is freezing a few seconds after startup. I am unable to use the mouse / keyboard. Neither Ubuntu nor Arch do anything after a few seconds. Windows has been running fine for years now. ...
0
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2answers
48 views

how to untar file in linux red hat?

I am compiling linux red hat stable kernel on red hat linux and the error which I am facing is as below
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0answers
17 views

Can anyone tell me how to compile custom linux kernel? [duplicate]

I want to know the complete method of compiling of a linux custom kernel.
2
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1answer
122 views

Kernel Backport for Debian Jessie?

I installed the 32 bit version of Debian Jessie (8.0) on an Asus X205TA. The Asus X205TA laptop is quirky like a lot of Intel Baytrail Atom laptops/tablets in that it has 32 bit EFI but a 64 bit ...
2
votes
0answers
15 views

Using dkms to patch kernel

I need to apply a kernel patch(https://lkml.org/lkml/2015/3/31/929) to get my touch-pad working properly. I am thinking that I should be using dkms, to do this. Most of the stuff I am reading is about ...
2
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1answer
24 views

bdl_pos_adj: set IRQ timing workaround for hda-intel

I get following errors in my logs: kernel: snd_hda_intel 0000:00:1b.0: IRQ timing workaround is activated for card #0. Suggest a bigger bdl_pos_adj Google found some old posts here and ...
2
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0answers
483 views

Delayed write scenario

I was reading "The Design of the UNIX Operating System" by Maurice J. Bach and had a confusion. Suppose a process requests for a buffer for disk block number 18. The kernel searches for a free buffer ...
0
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1answer
22 views

Kernel modules for compiled kernel

I cannot find kernel-headers. For the first time I compiled and installed the latest kernel (4.0.3) on my Debian Wheezy, and now I am trying to install ndiswrapper using module assistant. For that, ...
0
votes
1answer
20 views

Why does user mode linux spawn 4 processes?

If I start User Mode Linux with this command: ./kernel32-3.19.8 ubda=./Debian-Wheezy-x86-root_fs mem=128m On Debian GNU/Linux 8 (jessie) with one CPU core, why do I see 4 processes in top: 1608 ...
2
votes
1answer
495 views

Wireless constantly reconnecting on Ideapad running Arch

I just bought a new laptop, a Lenovo IdeaPad U330 touch, and after some struggle (with the Secure Boot stupidity) I have managed to install Arch Linux. I have configured my system, installed all the ...
0
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0answers
27 views

Linux Driver for USB “reverse” mass storage device

I'm developing a USB device that I want to read and write in virtual filesystems that are in my computer. Basically the device needs to be able to read, write and get the virtual filesystem size. Some ...
0
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2answers
43 views

how to check a kernel version which was used when building package

I use apt when downloading packages from Ubuntu repositories. How can I check which kernel version was used when building package? When it is important (kernel version of the build server vs. kernel ...
0
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1answer
34 views

Not able to reinstall the kernel or to use the latest version

On a ubuntu server, I try to di "sudo modprob" and I have this error : $ sudo depmod [sudo] password for deployer: depmod: ERROR: could not open directory /lib/modules/3.8.0-38-generic: No such file ...
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0answers
26 views

READ DMA Error after Installing CentOS 7

I have been trying to install CentOS7. After I installed it, I see the following message sporadically. ata2.00: exception Emask 0x10 SAct 0x0 SErr 0x4050000 action 0xe frozen ata2.00: irq_stat ...
0
votes
1answer
27 views

Downgrade Debian kernel

I have a requirement to install Debian kernel 3.2.65-1+deb7u2. I cannot seem to find the kernel. I have taken the following steps: Installed kernel 3.2.68-1+deb7u1. Downgraded the kernel to ...
4
votes
1answer
2k views

Setting up HDMI output from Linux console

I am currently running Debian Wheezy on a HP Microserver N54L with an AMD Radeon 5450 video card. I would like to be able to play audio from the console through the HDMI port of my video card and ...
1
vote
2answers
34 views

why do some network cards need to load external firmware?

I have read this question/answer, but I still do not understand why some network cards work perfectly well without any additional firmware, whereas others need to load firmware to work. As a specific ...
1
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0answers
34 views

Limit system processes using cgroups

My server runs several dozens of processes that are not in my control (mostly monitoring software). According to my application logs, sometimes some of the third party processes try to allocate too ...
0
votes
1answer
22 views

GNU\Linux clustreing , Which level? Which application? [closed]

I need to start GNU* clustering, But I have problem, Which level: DB level? (replication) file system? (distributed) process level ? (such as intel fortran for civilization softwares) new process ? ...
1
vote
1answer
491 views

Why system call hooking produces different result everytime in Linux/Android 2.6.29?

I have implemented system call hooking for Android 2.6.29 kernel through a LKM module. I am tracing down one Android app for system calls. But interestingly, it returns different results every time I ...
0
votes
1answer
12 views

Uprobes Status on the present linux kernel

I know uprobes was introduced on kernel 3.5 has it survived or is it dropped, is it still available on kernel 4.x
62
votes
3answers
112k views

How do you empty the buffers and cache on a Linux system?

Prior to doing some benchmarking work how would one free up the memory (RAM) that the Linux Kernel is consuming for its buffers and cache?
2
votes
2answers
6k views

Building example device driver error: insmod invalid module format

I am following the tutorial @ http://www.embeddedsystemonline.com/home/embedded-system/embedded_linux/lab3-linux-device-driver on step #7 of this tutorial, $ cd ...
0
votes
0answers
17 views

RHEL6 Idle Thread Behavior

I am doing some cpu performance profiling with the perf tool on a RHEL6 box running weblogic12g. It looks like the idle threads are presented as native_safe_halt in the stack profile but ...
0
votes
2answers
53 views

why can't we install application compiled for Ubuntu, on Linux mint, or some other distros with same kernel?

When i try to download some applications like VLC, it shows in download options, various Operating systems which includes Linux mint, Ubuntu etc. Though Linux mint's kernel is from Ubuntu, still they ...
3
votes
4answers
138 views

None of the linux programs work except 'cd'

Before stating the question, here's what I did and observed before the problem started: On a fedora 18 Xfce, I tried compiling 3.6.10 kernel with a cdv driver, After many attempts, it finally ...
0
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0answers
15 views

Filesytem errors during boot

I am using OMAPL138 and kernel version 2.6.37 and I would like to improve the boot time of my system. I made some progress on this, but I still have some errors which may be causing delay in the boot ...
2
votes
2answers
2k views

running kernel on QEMU

I face this message: Failed to execute /initKernel panic - not syncing: no init found. Try passing init=option to kernel. I am using this command line: qemu-system-x86_64 -hda disk.img -kernel ...
0
votes
1answer
103 views

Centos 7.1 still using outdate kernel 3.10 how to upgrade to kernel 4.0

I'd like to upgrade my Centos 7.1 kernel from 3.10 to 4.0 i did successfully in Ubuntu 15.04 using Linux 4.0.1-040001-generic even though i updated it manually it's works fine so please could ...
0
votes
1answer
114 views

VMware and kernel 4.0

I'm trying to install VMware in Elementary OS freya updated with kernel 4.0 but it doesn't start. The error suggests incompatibility with kernel 4.0. How can I solve this?