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

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Is there a way to permanently exclude the kernel from updates?

I'm using Fedora and wonder if there is some way I can exclude kernel updates when I run yum update, until I specifically want to update the kernel. The reason why I am concerned about this is ...
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1answer
82 views

Linux kernel: task vs thread

When I was reading a book(Linux kernel programming), I got interesting/confusing paragraph about mm_segment_t addr_limit(one of the member in struct_task) as below: mm_segment_t addr_limit; ...
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3answers
70 views

how is page size determined in virtual address space?

Linux uses a virtual memory system where all of the addresses are virtual addresses and not physical addresses. These virtual addresses are converted into physical addresses by the processor. To ...
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4answers
360 views

Run command when temperature exceeds threshold, without daemon

I need to run a specific command if my laptop gets too hot (for example, send a STOP signal to Firefox or Virtualbox in order to prevent my laptop from shutting down violently and damaging my hard ...
3
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1answer
41 views

OOM Killer value always one less than set

I am trying to set the oom_adj value for the out of memory killer, and each time I do (regardless of the process) I get back exactly one less than I set (at least for positive integers. I haven't ...
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2answers
3k views

Can vmlinux be used instead of uImage?

I want to use an uncompressed kernel image and boot the BeagleBoard. Generally I use uImage to boot the kernel which is in compressed format. How do I use an uncompressed kernel image?
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3answers
135 views

Control how linux deletes files

What exactly happens when an application deletes a file? Is there any way to control this behavior? Basically I want to shred instead of rm in all cases, but of course applications do not make calls ...
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1answer
34 views

Getty instances in init process

Init typically will start multiple instances of "getty" which waits for console logins which spawn one's user shell process. Upon shutdown, init controls the sequence and processes for shutdown. The ...
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1answer
26 views

filesystem that works under qemu and I can mount on my host

I'm using qemu for different kind of tasks, I would like to pick a filesystem that is both qemu-compatible and easy to mount under my host. I already discarded both qcow and qcow2 because apparently ...
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1answer
206 views

Kernel 3.12 or 3.10? which one has more features, newer and better?

Based on https://www.kernel.org/ kernel 3.12 is released in 2014-04-23 and kernel 3.10 is released in 2014-04-27. Based on release date, 3.12 is older and based on version number 3.10 is older. Which ...
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Some questions compiling linux kernel with make-kpkg

I'm doing my first steps compiling the linux kernel and adding a new system call. I've managed to do it, but I still have some questions. For this task, I has set up a Virtual Machine guesting debian ...
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1answer
18 views

Build kernel with multi_v7_defconfig setting

What is multi_v7_defconfig used for and how do I build the Linux kernel with this? I think I can write this into config file as: CONFIG_multi_v7_defconfig=y Please correct me if I'm wrong.
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How can I boot with a compressed rootfs?

My problem is: I cannot use compressed rootfs (the kernel crashes during boot) but uncompressed ones work fine. What I did: I'm using Buildroot 2013.11 to generate Images for my embedded Linux ...
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1answer
89 views

set permission 0666 on /dev files at boot time

I have to load a few additionals modules. One of them generates /dev/knem file. I have to set the permission to 0666, so a basic chmod 0666 /dev/knem works, but I would like to assign it directly at ...
2
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1answer
137 views

Why isn't the -rt (RT-Preempt) kernel patch included by default in the mainline kernel?

According to https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO , the RT-Preempt patch converts Linux into a fully preemptible kernel. The magic is done by: Making in-kernel locking-primitives ...
4
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1answer
199 views

Using a custom name for root device in GRUB

I'm working on old distro ( slackware 8.1 ) using a kernel 2.4.37.9 and I have the following problem. I want to use a custom name for boot device, say for example /dev/root1, which can replace the ...
4
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1answer
165 views

kernel: disabling /dev/kmem and /dev/mem

I understand that /dev/kmem and /dev/mem provide access to the memory (i.e. raw RAM) of the system. I am also aware, that /dev/kmem can be completely disabled in kernel and that access can be ...
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0answers
80 views

How can I compile minix when I make changes in libraries

I am looking for a way to compile minix. The make hdboot command seems to do nothing with the directories under /usr/src/lib. I changed only one .c file in syslib. Do I have to do make world for this ...
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2answers
108 views

Upgrading the kernel in Redhat Linux 6.0

How do you upgrade the kernel in Redhat Linux 6.0? And how can I confirm whether it is updated or not?
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1answer
240 views

How to specify an ISO as the location of root filesystem for GRUB?

I'm trying to understand the Debian "booting from Hard Disk" installation manual. The process is as follows: I copy a kernel image, a ramdisk initrd and an ISO with installer to the hard drive and ...
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2answers
80 views

How to query EFI signature

It appears that Grub-EFI will only boot a "signed" Linux kernel. Is there some command that will allow me to query a given kernel image to find out what signatures (if any) are present on it?
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1answer
42 views

Should I upgrade Ubuntu 12.04 kernel [closed]

I am currently running the 3.5.0.48 kernel on my Ubuntu 12.04.4, and I was wondering whether I should upgrade to 3.8 or 3.11. This makes it seem easy enough. Though I will wait with throwing away my ...
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Debugging a “brutal” system hang (no longer responds to Alt+SysRq+B)

I've had a series of system hangs where I hoped to get a crash dump to at least get some clues but the normal "magic sysrq" functionality is broken too; not even the immediate reboot key works. The ...
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1answer
68 views

Kernel optimiziations for ioctl AF_INET operations

Our server solution handles many tunnel operation requests (add/update/delete) using the ioctl interface, and the AF_INET address family socket. Aprox. numbers are 100 operations/minute with over 8k ...
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2answers
116 views

FATAL: Module hello.ko not found

I'm using CentOS-6.5 and default kernel is 2.6.32-431.11.2.el6.x86_64. I downloaded 2.6.32 and built that kernel (under /lib/modules/2.6.32). I wrote a module for simple hello world program. This ...
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69 views

Ubuntu kernel source code package

Can somebody explain me the difference between the following files: drwxr-xr-x 28 root root 4096 Apr 22 12:04 linux-lts-raring-3.8.0 -rw-r--r-- 1 root root 15209788 Mar 14 03:38 ...
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modpost.h:12:23: fatal error: elfconfig.h: No such file or directory

I am running Ubuntu: #lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 12.04.4 LTS Release: 12.04 Codename: precise Kernel info: 3.8.0-38-generic ...
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1answer
291 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
94 views

What does this dd command do exactly?

I have the an embedded device with this SD card: [root@(none) ~]# busybox fdisk -l Disk /dev/mmcblk0: 3965 MB, 3965190144 bytes 4 heads, 16 sectors/track, 121008 cylinders Units = cylinders of 64 * ...
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Can I use lldb to remotely debug the Linux kernel?

With GDB, I can remotely debug the Linux kernel. lldb, which promises to completely replace GDB, should be able to remotely debug the Linux kernel too. However, I cannot find any tutorial about this ...
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2answers
50 views

Block physical console access

I'd like to block physical console access to my linux. I'd like to find, which module is responsible for keyboard input (ps/2, usb, ...) and vga output (only physical), so I can remove them from my ...
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1answer
63 views

Do I have to compile the kernel every time, even for a small change?

In my project I configure the kernel (2.6.32) in block/ioctl.c. We all know that kernel compiling and building takes few hours. Even for a small change, I'm compiling from scratch. So is there any way ...
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Passing data from kernel space to user space in FreeBSD [closed]

I need some information regarding write requests from all applications on FreeBSD. I put a function inside the file system write call ffs_write() which collects the information into an array of ...
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3answers
77 views

Placement of kernel binary and sources for kernel module building?

I'm trying to setup an environment for kernel module development in Linux. I've built the kernel in the home folder and would like to place the sources and binaries to the correct place so include ...
4
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1answer
54 views

What does “make install” do in the Makefile that comes with the kernel?

I'm trying to identify what does make install do with the kernel and what does the actual "install" of the kernel once it's been compiled means. The problem is I can't really identify the target ...
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how get net switch info in soc?

I have a router device. cpu is mtk7620n. mtk7620n have a switch. How can i get information of the switch . swconfig show nothing. i think the switch have no driver. Anybody give me some ...
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1answer
56 views

Starting my own application at the startup

I am working on zc702 board having ARM Cortex A 9 processor. I have a binary that I got after cross-compilation for ARM (LED blinking). Now I want that this file should execute as soon as the the ...
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2answers
157 views
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1answer
73 views

How to create a custom Linux distribution? [closed]

Can any one tell me the easiest way to create a system with live cd with installing function. Which can install backtrack all tools?? I need to create a custom boot animation and everything!
2
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1answer
30 views

What is the difference/relation between kernel name and OS name?

What is the difference/relation between kernel name and OS name? Are they always the same thing? For example, I am puzzled at the outputs: -bash-4.1$ uname -s Linux -bash-4.1$ uname -o GNU/Linux ...
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2answers
110 views

What is the difference of kernel/distribution's release and version?

I use the following command to see the name, release and version of a kernel. -bash-4.1$ uname -s Linux -bash-4.1$ uname -r 2.6.32-279.el6.x86_64 -bash-4.1$ uname -v #1 SMP Wed Jun 13 18:24:36 EDT ...
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1answer
42 views

Correct location of initramfs.cpio file when compiling kernel

I am following this article and generated an initramfs.cpio file. Now the tutorial mentiones that I have to put this file in build directory: Finally, you have to rebuild the kernel again: # 0. ...
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1answer
152 views

Why isn't “REISUB” working on Debian?

I'm using Debian 'Jessie'. Sometimes my computer freezes, and then I can't use Ctrl+Alt+Supr to reboot, Ctrl+Alt+Backspace to kill the X Window System nor Ctrl+Alt+F1 to open a new shell. I've read ...
0
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1answer
44 views

How to use a built in driver in the kernel?

I am building the 3.14 kernel for a board that requires the intel e1000e driver. I would like this kernel to have the driver built in so that I can remove loadable module support. I have chosen the ...
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0answers
110 views

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 ...
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3answers
96 views

Enabling IP forwarding at kernel compile time

I am compiling a kernel for a router. I know a way to enable IP forwarding in an existing Linux system. At compile time, CONFIG_IP_FORWARD is said to do the same task. I am configuring version ...
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909 views

Kernel panic not syncing : Attempted to kill init

OEL 5.9 (Tikanga) 2.6.18-371.6.1.0.1.el5 On boot I get the following errors: ... exec of init (/sbin/init) failed!!!: No such file of directory Kernel panic - not syncing - Attempted to ...
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2answers
847 views

Skip all new device drivers in `make oldconfig` for Linux kernel

When using make oldconfig I usually look at new options briefly in case there's something important/useful. However, on an existing system I couldn't care less about new device drivers for some ...
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1answer
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Where are the files created by “make modules” when building and compiling the Linux kernel?

To build the kernel, I do make menuconfig make make modules For step3, where do the files go? What's the location for modules? Can I change it by using any env variables?
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Linux distro with PREEMPT_RT patch

I want to know if there is any Linux distribution with PREEMPT_RT kernel patch? If not, is there any good tutorial on how to patch and compile a kernel with RT patch and how can I create kind of a ...