Tagged Questions

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

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0
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2answers
241 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 ...
2
votes
0answers
124 views

Is there a way to undo VGA adapter modesetting in Linux

I'm looking for a way to reset the graphics adapter to textmode after it has been set to some sort of graphical mode by the kernel on bootup, and possibly used by an X server. Is there any code to do ...
1
vote
1answer
90 views

How to give an ordinary user privileged access to a particular syscall in FreeBSD?

I want to give an ordinary user the ability to fchown() files arbitrarily (as if they were the superuser) on FreeBSD. Generally speaking, is there a right way to change the privilege-checking of a ...
0
votes
0answers
178 views

pptp differs between 3.7 and 3.8 linux kernel milestone with 3.2.0-4 milestone

Unfortunately, current kernel of debian has problem with my hardware: 3.2.0-4-686-pae , and when i compile one of 3.7.x milestone or 3.8.1 itself , my problem is solved. But my problem with new ...
2
votes
2answers
221 views

Linux kernel development for multi core architecture

I am working on a project adapting system software like the Linux kernel. I read one paper titled "Experience on Comparison of Operating Systems Scalability on the Multi-core Architecture" that tells ...
0
votes
2answers
572 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 ...
14
votes
3answers
10k views

How to cause kernel panic with a single command?

Is it possible to cause a kernel panic with a single command line? What would be the most straightforward such command for a sudoing user and what would it be for a regular user, if any? Scenarios ...
5
votes
3answers
150 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 ...
0
votes
1answer
195 views

How does kernel swapping / INT 13h interrupts work?

I'm looking for a way to learn about and understand this technique. Here's what I'm talking about: Slax boots, {does stuff, like copy itself to RAM}, then transitions control to the kernel/file ...
3
votes
2answers
1k 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 ...
2
votes
1answer
333 views

Kernel headers for VMware tools

I tried to compile VMware tools on my server. I compiled the kernel myself, I didn't use RPM. As VMware tools needs the kernel header files, I executed the following command in my kernel folder ...
0
votes
2answers
683 views

Kernel/grub : how override root parameter inside initrd script

I have an old kernel ( 2.4.37.9 ) and I want to override or substitute the root=XXXXX parameter to send to the kernel inside the initrd script. I already made some attempt to do that but it seems ...
4
votes
1answer
285 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 ...
5
votes
3answers
1k 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
vote
0answers
384 views

Lowering kernel timer interrupt frequency

When I run my Virtual Machine with Gentoo as guest, I have found that there is considerable overhead coming from tick_periodic function.( this is the function which runs on every timer interrupt).This ...
3
votes
2answers
482 views

If I redirect logs using rsyslog, will dmesg be affected?

I am trying to get some logging in place and am trying to troubleshoot it and this question became relevant. I use rsyslog config files to redirect some of my logging. (Will use iptables logging ...
1
vote
1answer
242 views

Initrd : Were can I found the code for real-root-dev

I'm trying to customize my initrd on kernel 2.4. At some point, inside the file linuxrc, I have the opportunity to set my root device setting the /proc/sys/kernel/real-root-dev variable The example ...
4
votes
3answers
538 views

How to list all hardware supported by kernel

I want to see all hardware supported by the kernel in use. For example, if I have the 3.8.x.x version of the Linux kernel, how will I know what hardware is supported there. Tools like lspci, lshw, ...
35
votes
4answers
43k views

What is the difference between reboot , init 6 and shutdown -r now?

I just want to know difference between in reboot init 6 shutdown -r now and which is the safest and the best?
1
vote
0answers
1k views

Intel Core i3/i5/i7 Sandy Bridge CPU throttling

Intel Sandy-Bridge family i5 Core CPU, running Linux kernel 3.2 (Debian Squeeze/Wheezy), under heavy computation load, does not react to to cpufreq-set -g powersave (using acpi_cpufreq module). It is ...
2
votes
1answer
124 views

What is the source of truth for currently active tty/pts connections?

I'm looking for a simple way to determine the number of currently logged in users, using only the filesystem and basic bash functions (instead of using binaries). The uptime binary appears to be ...
1
vote
2answers
273 views

TLB cache flusing when a page is swapped out

I recently heard that Linux simply flushes the TLB cache when the corresponding data in that physical address is swapped out, resulting in underutilization of the TLB. I don't know whether all OSes do ...
7
votes
1answer
2k views

Writing /dev/random to file?

If you ran the following, what would happen? cat /dev/random > ~/randomFile # don't run Would it be written until the drive runs out of space, or would the system see a problem with this and ...
0
votes
1answer
44 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.
1
vote
1answer
651 views

How to avoid overflowing the kernel printk ring buffer?

I'm trying to debug a linux driver and a particular piece of code is behaving very strangely. In order to see what's going on I've filled the code with printk statements so I can see exactly what the ...
8
votes
1answer
1k views

Blocking kernel updates with dpkg

I'd like to block all distribution-shipped kernel updates due to a nasty thing that recently happened to me. (I'm on a Ubuntu 12.04 amd64 derivative.) I'd like to block all updates to installed ...
2
votes
1answer
949 views

Kernel config for ASUS P8Z77-V mainboard series

I want to build a kernel (3.6 series) for a system with a ASUS P8Z77-V mainboard. Which settings fit to the built in components? (The ideal answer would contain an example .config for this board.) # ...
2
votes
0answers
56 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 ...
2
votes
1answer
500 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 ...
1
vote
3answers
1k views

How to know <root of the kernel source tree>

In https://github.com/facebook/flashcache/ there is a saying make KERNEL_TREE=<root of the kernel source tree> This builds both the flashcache.ko and 3 utilities. ...
2
votes
0answers
306 views

Failed to execute shell script from “network” udev rule to change the MAC-address

I am trying to execute a shell script from udev rule, when a network interface is added, as follows: SUBSYSTEM=="net", ACTION=="add", KERNEL=="eth*", PROGRAM="/usr/local/bin/changemac.sh", ...
12
votes
1answer
2k views

Why does Red Hat Linux use such an old kernel?

Why does RHEL (and its derivatives) use such an old kernel? It uses 2.6.32-xxx, which seems old to me. How do they support newer hardware with that kernel? As far as I know these kind of distributions ...
1
vote
1answer
506 views

Compile Linux Kernel w/ Dynamically (Un)loadable usbserial Module

I've attempted to install drivers for an FPGA device, but require that I remove the usbserial module. This happens to be impossible because usbserial is a built-in module. It was suggested that I ...
-1
votes
2answers
116 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?
1
vote
1answer
1k views

Removing builtin modules in Linux

I'm currently attempting to remove the usbserial module in order to install a new driver module. When I attempt to remove the module I get the following issue: [root@localhost xr21v141x-lnx-3.0-pak]# ...
2
votes
0answers
625 views

Kernel does not detect Hardware / Software or Hardware fault

I've got more of a basic question for you: My linux kernel (I tried several here from stock 2.6, 3.2 and 3.5 as well as a custom 3.7.3 one) does not detect my synaptics touchpad - or I'am too dumb ...
4
votes
1answer
2k 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 ...
0
votes
1answer
363 views

Linux + Kernel panic

when I reboot my Linux machine Linux version 5.5 red hat I get the following warning on the console screen , Linux cant startup and I can't login please advice , how to login as single user mode and ...
2
votes
1answer
888 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 ...
2
votes
1answer
407 views

Installing the kernel EFI stub loader in kernel 3.2?

Kernel EFI stub loader support was added in kernel 3.3, but I'm stuck on 3.2 running an Ubuntu 12.04 64bit distribution. Is there a way for me to somehow bring that stub loader support into my kernel? ...
3
votes
2answers
295 views

Misleading explanation of Virtual Memory in TLDP

I'm completely confused about explanation of virtual memory in TLDP: http://www.tldp.org/LDP/tlk/kernel/processes.html#tthFtNtAAB They say: Each individual process runs in its own virtual ...
1
vote
1answer
430 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 ...
2
votes
1answer
514 views

How to decode cmd = 3222823425 in ioctl in Linux 2.6.29

I am just confused like how can I break cmd=3222823425 value into different parts to figure out what this command means actually in the Linux kernel. I know, some functions are making ioctl command ...
10
votes
4answers
23k views

Determining cause of Linux kernel panic

I'm running an Ubuntu 12.04 derivative (amd64) and I've been having really strange issues recently. Out of the blue, seemingly, X will freeze completely for a while (1-3 minutes?) and then the system ...
4
votes
2answers
2k views

Is it normal that Fedora's yum list kernel-* shows two versions of kernel being used?

Is it true that the following shows that two versions of the kernel are being used? (Is the bold face -- the one enclosed in ** showing what is currently loaded / used). Basically, I just created a ...
2
votes
0answers
340 views

Booting over the LAN using uboot

I am trying to boot my beaglebone over the LAN. I am able to download the Kernel uImage from the TFTP server. Here is what I did - U-Boot SPL 2011.09-00053-gb423c52 (Aug 10 2012 - 11:26:55) Texas ...
1
vote
0answers
48 views

How to find system call implementations in Linux/Android 2.6.29? [duplicate]

Possible Duplicate: Understanding the Linux kernel source I want to modify some system calls for tracing purposes. To be specific, whenever a system call open is made, I want to print some ...
2
votes
2answers
1k 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 ...
4
votes
3answers
124 views

What is contained in these addresses?

I am working on MUlti-processor record-replay feature of a virtual machine. I have a log of non-deterministic memory access done in the virtual machine by virtual CPUs. A very high proportion of these ...
2
votes
1answer
722 views

Build kernel in one machine, install in another

I want to build my Linux kernel on my host and use it in my VWware virtual machine. They both use the same Ubuntu kernel now. On my Host, I do make and make configure. Then, what files should I copy ...