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

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2answers
2k views

Linux kernel is not finding the initrd correctly

I had compiled a linux kernel and I wanted to debug it in QEMU. I created a file to boot from by doing the commands $ qemu-img create -f raw disk.img 200M $ mkfs.ext2 -F disk.img # mkdir /mnt/rootfs ...
2
votes
5answers
181 views

How to know what to enable in the kernel?

I'm a gentoo user. When compiling the kernel there are a lot of options which one may enable depending on one's hardware. My question is how to know what to enable/disable, I'm aware of the hardware ...
0
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1answer
2k views

Installing qemu-img on ubuntu 11.04

I am developing a linux kernel and I am trying to to debug it in QEMU. I want to be able to run it in QEMU but it stops because I do not have a virtual hard drive to boot it(using the -hda command). I ...
0
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2answers
228 views

Writing a Linux file system for NFS

I want to write my own custom file system in Linux. Can I share it over standard NFS without making any changes to the local NFS server? If so what VFS APIs are required to be implemented by my file ...
1
vote
1answer
62 views

Multi kernel usage in Linux PC(UBUNTU)

I have 2.6.32-21-generic , 2.6.32-38-generic and 3.0.0-20-generic. My current kernel is:- $ uname -r 2.6.32-38-generic I want to use different kernel that is 2.6.32-21-generic. How can I do that?
0
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2answers
304 views

Compiling the Linux kernel in Eclipse

I have a Mac running Snow Leopard and I know that I cannot compile the Linux kernel. I have used a Linux VM (virtualbox) to compile the kernel but I was wondering if I could compile it on Eclipse ...
0
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1answer
793 views

Invoking memory compaction on linux 2.6.35 kernels and beyond

This LWN article about memory compaction indicates that memory compaction can be invoked in the linux kernel by Writing a node number to /proc/sys/vm/compact_node, causing compaction to happen on ...
1
vote
1answer
864 views

How can I disable IPv6 in custom built embedded setup

I have an embedded system built using buildroot. I have had a number of network issues, one of which is that my machine cannot see its gateway despite it being on the same subnet. I have tried using ...
1
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1answer
195 views

core dump help— linux

I'm trying to understand the core dump generation. Is the core dump generated separately for a user space application process crash and the kernel level crash? Is the ulimit -c for both kinds? Can you ...
0
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2answers
399 views

swap partition and its laws

I remember for choice of swap partition, we should use (swap > 2xRAM) at least.Of course it deprecated , because max of computer's ram is very high. kernel support it. My question: i remember each ...
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0answers
23 views

Best way of updating Openssl on Linux machine [duplicate]

I have a confusion to choose the best way for upgrading the OpenSSL on my Linux machine. 1*Through the yum Update.* # yum update I know this will update the entire packages. But If I want to ...
2
votes
2answers
179 views

How to edit grub2 to use kdump?

I was following http://fedoraproject.org/wiki/How_to_use_kdump_to_debug_kernel_crashes and in step 2 I need to add the line to grub.cfg, but grub.cfg is a shell I do not know how to edit it, most ...
4
votes
1answer
2k views

Is it possible to run any distro from RAM from within an .iso saved on an NTFS file system?

Running entirely from RAM been done on various distros such as Slax, DamnSmallLinux, and newer Ubuntu versions, and since I have 8GB it seems reasonable that I could run many distros entirely from RAM ...
2
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0answers
183 views

Update jiffies value after waking up from suspend

The global variable jiffies holds the number of ticks that have occurred since the system booted. On boot, the kernel initializes the variable to zero, and it is incremented by one during each timer ...
5
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3answers
895 views

Disadvantages of linux kernel module?

I am trying to understand the disadvantages of using Linux kernel modules. I understand the benefits of using them: the ability to dynamically insert code into a running system without having to ...
1
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0answers
243 views

Is there any ARM platform for which high resolution timers are available in mainline (unpatched) kernels?

I currently have some projects using a TS-7400 board, which has a Cirrus Logic EP9302 ARM9 processor. Some of my applications require a 1ms periodic timer, so after lots of struggling I found these ...
29
votes
7answers
4k views

Why does mount require root privileges?

Why does Linux require that a user be root/using sudo/specifically authorized per mount in order to mount something? It seems like the decision as to whether to allow a user to mount something should ...
1
vote
1answer
388 views

Change of real time priority made no visible effect

we were trying to get the best result with software PWM on raspberry pi with Raspbian. We made a python script which starts PWM on a GPIO pin, and observed the results with the oscilloscope. It ...
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vote
0answers
163 views

How customize initrd via linuxrc

I have the need to use the same disk and so the same bootloader on devices with different motherboard. Each motherboard has it's own way of mapping devices so sometime the bootdisk is mapped ad hda ...
4
votes
1answer
121 views

User Mode Linux compile fails

I am trying to compile User Mode Linux on a 64 bit machine with defconfig and getting the following error. arch/x86/um/user-offsets.c:1: sorry, unimplemented: code model "large" not supported yet ...
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vote
0answers
194 views

How to setup an audio/sound output monitor/listener?

I am working with an Arduino and am trying to get it to respond to sound when it is played on my computer. I'm communicating with it over a serial port. I need to know if there are any audio/sound ...
0
votes
1answer
42 views

USB_HID is not working

How do I get a usb keyboard to work? I have already selected and compiled the USB HID transport layer and I don't know what else to do.
2
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0answers
52 views

kgdb not returning control to gdb

I've compiled a kernel with kgdb support and I'm trying to debug it. I have two machines running, a debug machine (running the kgdb kernel) and the machine I'm using to debug it. They are connected ...
3
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0answers
215 views

My SMDK2416 (for s3c2416) kernel works on 64MRAM but crashed on 128M

I'm currently working on embedded arm linux with smdk2416(s3c2416) The kernel is working on the 64MRAM. Recently, I need to increase the RAM from 64M to 128MB with 64MB on bank0 and 64MB on bank1. ...
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1answer
1k views

make: *** No targets. Stop while building linux kernel module [closed]

I am just trying to learn how to driver modules for Linux Kernel. I followed Linux Device drivers 3rd edition book and started my work. I created a sample program and makefile. Please find my makefile ...
2
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1answer
439 views

USB3 Hard Drive Not Recognised by Linux

My external USB 3 hard drive is behaving very strangely: If I plug it into a USB 2 port, it works fine If I plug it into a USB 3 port, it doesn't work at all. It's not even mentioned in ...
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3answers
339 views

AES-NI on Dell Vostro 3360

I don't have AES-NI available on my Dell Vostro 3360 laptop. Why? Does this machine not support it? My /proc/cpuinfo: processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 58 ...
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2answers
2k views

Where can I find a good tutorial for installing bcache? [closed]

Question is updated. Now bcache is part of the standard OS compilation. So it should be easy to install that now. I'll just order some SSD and some big HDD. Where can I found it? I found on the net ...
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vote
1answer
219 views

Linux kernel 3.2 syscalls

Just trying to get the assembler instructions for <__execve> of the code below because i want to build the shell spawn opcode list: #include <stdio.h> int main() { char *happy[2]; ...
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vote
1answer
194 views

How to compile linux kernel and debug with gcc and BOCHS?

I have download bochs 2.6 sourcecode and installed with gdb-stub configuration. I would like to debug linux-kernel 1.0 or 2.0 or 3.0 which sourcecode downloaded from http://www.kernel.org/ with gcc ...
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3answers
566 views

Linux Kernel: uid and gid vs /etc/passwd

How does the Linux kernel deal with UIDs and GIDs? When I want to add a user to a system, does the kernel require some type of "registration" for this user (syscall?)? Does the kernel even care about ...
2
votes
1answer
1k views

Kernel and QEMU : Unable to mount root fs error

I am trying to run a distro in the virtual disk image with a custom kernel,so that I can experiment and debug the kernel. I followed this to make a disk image and then install Debian to it. Now I ...
12
votes
4answers
755 views

Linux on a 286?

I don't own a 286 nor do I intend to run Linux on one. However since the 286 has protected mode, why is it frequently stated that Linux requires a 386 CPU or higher? From ...
2
votes
0answers
2k views

mounting udev on /dev failed: No such device

I am trying to compile Linux kernel 3.2.36 with its source code on the x86_64 architecture. I followed the following set of commands under my Linux source distribution directory: make defconfig ...
2
votes
1answer
784 views

Debugging Linux Kernel with QEMU

I was trying to study the debugging of kernel using QEMU. I tried initially and failed due to the fact that there was no virtual file system. The answers to this post suggests that there should be a ...
7
votes
3answers
3k views

Why is the theoretical RAM limit for RHEL 6 128 TB and how is this determined?

I'm studying for RHCSA and am confused by a statement I came across in some training material: There is no practical maximum RAM, as theoretically, you could run 128 TB of RAM on RHEL 6. But ...
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0answers
335 views

Where does the Linux kernel reside in memory ?

From some book I have, I have in my notes that the Linux kernel resides at 0xc00000000 on 32-bit systems, and is mapped into user space for performance reasons. Is this accurate ? How can I verify ...
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0answers
90 views

Android strace error: “strace: 2: Syntax error: ”&“ unexpected”

I was using built-in strace given in /system/xbin/ directory in the emulator and it was giving me wrong set of system calls such as msgget() and msgrecv() which are not supported by Android even. I ...
1
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1answer
152 views

Linux, Debugger program development

We are trying to implement the debugger program which will takes either PID or Program name as input and Invoke the gdb by using PID. Below is two small programs are written, Not able to figure out ...
0
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2answers
781 views

After removing linux Grub error

I have a dual boot Windows & Linux system. I removed the Linux partition, but after that I am not able to go in to Windows XP. It is not booting. It gives me a GRUB error.
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0answers
113 views

Creating a Virtual filesystem to boot linux

I am trying to boot the linux kernel (bzImage) in QEMU but have had issues. After asking on U&L I found out that my problem was that I was booting the kernel without a filesystem to boot from. So ...
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vote
2answers
753 views

Automatic kernel configuration tool

Is there any developed automatic linux kernel configuration tool? I have found a method of make localmodconfig, but it is certainly very limited. I have searched the web but unfortunately have not ...
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0answers
103 views

What changed in Linux kernel (2.6.22) that gives hdparm support for power-on in standby?

Hdparm man page lists for parameter -s: Enable/disable the power-on in standby feature, if supported by the drive. VERY DANGEROUS. Do not use unless you are abso- ...
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0answers
778 views

CFLAGS in Linux kernel makefiles: which one is used when?

I'm not familiar with Makefiles, I can kinda understand them, but with the Linux Kernel I have a question. (Using 3.7.1, Patched with BFS so line numbers may be a bit off) On line 248 HOSTCFLAGS ...
6
votes
2answers
2k views

How to set OOM killer adjustments for daemons permanently?

Running some Linux servers with single or just a few vital system service daemons, I would like to adjust the OOM killer for those daemonized processes in case something odd happens. For example, ...
5
votes
2answers
926 views

How is a Linux kernel capable of accessing its assigned initramfs/initrd?

I'm trying to understand the boot process of a machine as a whole from the time you hit the power button. There's this one piece from bootloader to initramfs stage I don't quite understand among some ...
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0answers
54 views

Would it be possible to not have the network link cycled on loading the kernel module?

Using some cheap hardware in a thin-client setup we use a diskless PXE booting a small Linux kernel. Currently, it takes a quite some time to boot it fully up and we're looking into some optimizations ...
2
votes
2answers
859 views

Finding out the values of kernel options related to sysctl.conf and sysctl.d

On my Ubuntu machine, in /etc/sysctl.conf file, I've got reverse path filtering options commented out by default like this: #net.ipv4.conf.default.rp_filter=1 #net.ipv4.conf.all.rp_filter=1 but in ...
2
votes
1answer
126 views

directions about customized Layer 2 implementation in linux

I have some machines running on the same network. One node is the control node which distributes traffic coming to it to the other nodes. The thing is that I want to have a custom protocol header ...
2
votes
1answer
334 views

Chain loading kernel without a boot loader

I am working on an embedded project that will do in-place upgrades. There may come a time when an upgrade will need to reinstall everything. Since this is a pretty risky thing, I would like to have ...