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

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795 views

Kernel can not boot after upgrade on Fedora OS 15

I am using Fedora 15, and want to upgrade to version 16. I followed the official link Upgrading Fedora using yum - FedoraProject to upgrade my OS by the following command: yum update kernel* --...
9
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3answers
4k views

Why does initramfs mount the root filesystem read-only

What is the reason for the root filesystem being mounted ro in the initramfs (and in initrd). For example the Gentoo initramfs guide mounts the root filesystem with: mount -o ro /dev/sda1 /mnt/root ...
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2answers
2k views

Restricting memory area for linux kernel

I am running ltib Linux on P1022RDK (P1022 Core) platform. I have 512 MB = 0x20000000 memory. I want my Linux kernel to use the second half of the board memory (i.e from 256 MB to 512 MB) and want the ...
10
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3answers
5k views

Make changes to /sys persistent between boots

I want to make "echo 1 > /sys/kernel/mm/ksm/run" persistent between boots. I know that I can edit /etc/sysctl.conf to make /proc filesystem changes persist, but this doesn't seem to work for /sys. ...
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2answers
1k views

Problem at boot-time: “Loading user-defined modules [FAIL]”

After I updated my Kernel to version 3.0, i always get this line when my Arch-Linux system is booting up: Loading User-specified Modules [BUSY] [FAIL] I have no idea what could cause this to ...
10
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3answers
18k views

How can I know which IRQ is responsible of high CPU usage

I've moved a server from one mainboard to another due a disk controller failure. Since then I've noticed that constantly a 25% of one of the cores goes always to IRQ however I haven't managed myself ...
8
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2answers
166 views

Signing/Checksumming the kernel to prevent/detect manipulation

All my partitions are encrypted (/ and /home), but the /boot partition has to remain unencrypted and is open for manipulation. I was thinking about hashing the kernel on bootup and checking the result ...
3
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1answer
3k views

Change the number of generated /dev/tty devices

I'm building an embedded Linux system, based on Gentoo. Using udev, all tty devices are probed with a PROGRAM stanza to determine if they are a modem. Right now the system boots up with 64 /dev/tty*. ...
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1answer
18k views

How to generate Module.symvers?

I recently went through Unpacking kernel-source rpm off-system (OpenSuse)?; and as it took > 10 h on my machine, imagine my surprise that after doing the process described there, I find no Module....
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1answer
836 views

Switching from Debian 6 Squeeze stable to testing version

I had this problem and I asked some friends of mine and their advice was to upgrade from my messed-up Debian Squeeze system to the testing version. So I did it. First I changed the /etc/apt/sources....
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3answers
3k views

rewrite existing file so that it gets replaced by new version atomically, only once fully written

I vaguely recall reading somewhere that there used to be, in some Unices a way to open an existing file for writing, with a flag that asked the kernel to use the old version (for other processes ...
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1answer
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create a debian installer with custom kernel

First what I need to do is install a debian on a 3300mx computer which is based on a vortex cpu. The problem is the debian installer always crash because the required drivers are in the kernel as ...
2
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1answer
145 views

Is it possible for grub2 to detect some specific CPU features and choose a proper kernel to boot?

I want to configure grub to check some CPU features on startup and choose a proper kernel to boot (e.g. multiple cores -> kernel with SMP support). Is it possible? If so, then how do I do it?
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4answers
2k views

Stripped down Kernel for a Laptop

I am a Linux noob, but I am willing to learn. My immediate objective is to compile a small kernel for my laptop without sacrificing usability. I am familiar with the kernel compilation steps (don't ...
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vote
1answer
1k views

Is there a way to increase the 20 multicast group limit per socket?

As the title says, is there a way to increase the limit of 20 multicast groups that you can join on a given socket? Is there some system setting that I am missing or is there some hard limit which ...
2
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1answer
2k views

libusb_init() returns -99

I have successfully built both libfreenect (driver for Xbox Kinect) and libusb (which is a dependency). However, if I try to open the Kinect using the freenect_init(...) function, it returns -99. I ...
4
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1answer
4k views

How to update Debian kernel to latest in backports

I have a machine running Debian stable, and I'd like to update the stock kernel to the latest kernel available in the backports repository. There are many kernel-related packages and virtual packages--...
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0answers
191 views

What are the current differences between tuxonice and µswsusp?

I tried to find out what is the current comparation between TOI and µswsusp. Unfortunately I could not find any recent information about the state of hibernation in Linux and how TOI compares to ...
4
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1answer
3k views

What is the difference between /proc/self/stack and output from pstack?

I have been looking through the documentation for /proc and the "stack" object being a new'ish object in proc, I have also looked through the kernel commit to create it -- however the documentation ...
4
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1answer
2k views

Debian 6.0 system with 2.6.39 kernel dropping packets, sandy bridge hardware

I recently migrated an existing Debian system to new hardware, a core i3 chip running on an intel sandy bridge motherboard. I’m experiencing a very strange problem; when I ping my router, about 50% of ...
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5answers
18k views

Why is kworker consuming so many resources on Linux 3.0.0-12-server?

Last Friday I upgraded my Ubuntu server to 11.10, which now runs with a 3.0.0-12-server kernel. Since then the overall performance has dropped dramatically. Before the upgrade the system load was ...
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2answers
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What is the need of the struct thread_info in locating struct task_struct?

While reading through the Linux Device Drivers, I could understand that the Process Descriptor (of type struct task_struct) has all the info regarding a particular task. The process descriptors are ...
2
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1answer
606 views

regarding shared memory behaviour

Noticing a strange performance behaviour while using shared memory that are file backed (i.e open user defined file and mmap() the same into process space). While doing a memcpy() into the shared ...
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1answer
3k views

Custom kernel: fails to load firmware when module built-in

I'd like to have all my modules built-in, but this fails with iwlagn: iwlagn 0000:03:00.0: request for firmware file 'iwlwifi-6000-4.ucode' failed. iwlagn 0000:03:00.0: no suitable firmware found! ...
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1answer
833 views

How can nfs service in the kernel be disabled?

How can nfs service in the kernel be disabled? As far as I can see there are no userland utils # find / -name nfs* -print /sys/kernel/slab/nfs_page /sys/kernel/slab/nfs_inode_cache /sys/kernel/slab/...
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3answers
4k views

Increasing kernel memory size

I have an embedded board with 512MB of RAM running Linux 2.6.29 and UBoot bootloader. But the kernel is able to utilize only 128MB of RAM. I tried changing the value of XCODE_MEMSIZE, which I think ...
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1answer
1k views

Linux kernel 2.6.38 compilation error

When I try to compile the Linux 2.6.38 kernel on my Linux PC, I get: $ make defconfig $ make I get: ubuntu/ndiswrapper/iw_ndis.c:1966:2: error: unknown field ‘num_private’ specified in initializer ...
3
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1answer
2k views

How to capture from instensive pro in Ubuntu, Fedora, CentOS using HDMI interface?

I am trying to use PCI-X1 capture card (intensiy pro) using Ubuntu 10.04 (now) / 11.04 (failed) or Fedora (failed). None of them is yet capturing. I did my best but now i need some backup on this. ...
5
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1answer
4k views

What is a “watchdog reset”?

After reading this question, I was a little confused; it sounds like some daemon reacting by rebooting a system. Is that right? Is it a common occurrence in embedded *nixes?
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2answers
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How do I cause a watchdog reset of my embedded Linux device

Is there a command like vi > out vi | out That I could use to cause a watchdog reset of my embedded linux device?
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1answer
1k views

Unable to boot custom kernel

I am using ubuntu 11.04 I have a custom 2.6.36.4 kernel source (say in linux_src) Did make mrproper Copied my current configuration from /boot to linux_src/.config Did a make menuconfig, instructed ...
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1answer
1k views

Using syslog from a kernel module

I am writing a linux kernel module to report statistics and send some log messages. Can I use syslog to accomplish this job? Or is printk the only way?
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3answers
870 views

How can I reconfigure my Ubuntu PC's 2.6.37.6 kernel to shrink it to 950 KB or less?

I need to recompile the kernel with minimum configuration so that after compiling its size stay below 950 KB and it should boot correctly after compilation. I need to compile with minimum possible ...
8
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1answer
818 views

Grubby fatal error in Linux kernel installation

I have compiled Linux kernel 2.6.24.6 from source (without problem) and tried to install it. Specifically, after unpacking the Linux source code, I did make && make modules to compile. ...
3
votes
2answers
406 views

Is there a different linux kernel for different architectures?

If I want to build a custom kernel for an ARM architecture, do I need to : a) Download the kernel from kernel.org, make changes to the kernel, build it using some cross compiler (like code sourcery ...
2
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2answers
380 views

UDP multicasting broken after kernel update

I've got an embedded system which is running a stripped down Gentoo userland with a manually build kernel. The system acquires data from a PCI card and sends it out to an UDP multicast group. All ...
3
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1answer
169 views

Does linux have Blackbox like mechanism when system crashed in embeded linux?

In embeded linux, some times after the system crashes, we hope there is a blackbox (will record the key info before the system restart) , in linux, is there have such kind of mechanism to record the ...
2
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1answer
121 views

Is there any method to mount a block of memory as a filesystem in linux?

I have a question,in linux, is there any method to mount a block of memory as a filesystem? For example, in X86 architecture, when power on, I reserve a block of memory about 8 Mbytes, and then when ...
4
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2answers
21k views

Command to install linux headers fails

I need to install my linux headers for an Nvidia driver install. But I get an error when doing so: peter@peter-deb:~$ sudo apt-get install linux-headers-$(uname -r) Reading package lists... Done ...
4
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2answers
387 views

Non-interactive configuration of linux kernel

Is there any method to configure linux kernel in such way (just an example): make config CONFIG_OPTION=y && make config CONFIG_OPTION1=no CONFIG_OPTION3=64 CONFIG_OPTION4=/path/ and all the ...
2
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1answer
219 views

rpm content compress

My default kernel rpm has 12mb size, for some reasons I compile a custom kernel and make rpm from that(make rpm command). However, my custom kernel rpm size is 96mb. I look inside default rpm, in ...
2
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2answers
544 views

How to use a custom crypto algorithm in ipsec?

I wrote a custom algorithm using the kernel crypto API (by modifying the existing SHA1 and DES algorithms), compiled and added the .KO object to kernel. How can I use my algorithm in ipsec and other ...
14
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1answer
11k views

Buffer size for capturing packets in kernel space?

Going through the man page of tcpdump, it seems kernel can drop the packets if the buffer is full. I was wondering if: that size is configurable and/or where can I see the size for my distro? From ...
14
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2answers
18k views

How to include local header files in linux kernel module

Say I have a module mymod with source files as follows: src/mod/mymod.c src/inc/mymod.h I try to include mymod.h as follows #include <mymod.h> My makefile contains EXTRA_CFLAGS= -I$(...
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3answers
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ACPI problem with recent kernels

In recent versions of popular Linux distributions (Ubuntu, Fedora, Mint, Debian) I always have to put acpi=off into the kernel parameter list before I want to boot the computer. This happens to both ...
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2answers
541 views

How to configure CONFIG_DEFAULT_RELATIME to disable relatime

Since linux 2.6.30, filesystems are mounted with "relatime" by default. In this discussion, Ingo Molnar says he has added the CONFIG_DEFAULT_RELATIME kernel option, which: makes 'norelatime' the ...
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2answers
6k views

Cleancache vs zram?

I have an old laptop here with only 512 MB of RAM. Since a few kernel releases, I am using zram to convert 256 MB of it to a compressed ramdisk which is then used as swap. This has proved to be very ...
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1answer
2k views

When was `relatime` made the default?

What is the first Linux kernel release to set relatime as the default mount option?
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2answers
1k views

Why do I get this error installing virtualbox-4.1 on Arch?

I'm trying to install Virtualbox 4.1 from the .run file since Pacman had the 4.0 version only. But when I try installing the file using sh filelocation/filename.run, it gives me the following error- ...
4
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2answers
370 views

Is there a vanilla kernel configuration?

A question on Ask Ubuntu asks if there's a vanilla kernel for Ubuntu. Its answer is there is a "Mainline" series of kernels for Ubuntu that use vanilla files with Ubuntu configurations. But how ...