This tag is for questions about the internals of the Linux kernel itself - particularly about use or configuration of kernel modules or drivers.

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11
votes
6answers
19k views

How do I uncompress vmlinuz to vmlinux?

I have already tried uncompress, gzip, and all other solutions that come up as google results and these have not worked for me. To get just the image search for the GZ signature - 1f 8b 08 00. ...
10
votes
1answer
6k views

Linux overcommit memory

I've been looking into memory overcommitting in Linux using /proc/sys/vm/overcommit_memory, and I've read a few articles which don't say the same thing. This doc, under the heading "Going in the ...
9
votes
4answers
1k views

Does linux have any measures to protect against fork bombs?

#include <unistd.h> int main(int argc, char* argv[]) { while(1) { fork(); } } I run this program on my linux, nothing outputs on the terminal, the OS seems go dead. Does linux have ...
9
votes
2answers
2k views

Directory - /sys in linux

Can anyone explain me what is going inside the /sys directory on a Linux system? I Googled it and got some results, but I need a clear mind on this. Is there anyone ready to give me a short (and ...
9
votes
5answers
12k views

What does “sudo -s” actually do?

I am using ubuntu 10.04. I notice that after I run "sudo -s" in terminal, the prompt changed from "XXX@XXX" to "root@XXX", seems it changed to root privilege. But when I check the ...
8
votes
2answers
9k views

how to totally clear the filesytem's cache on linux?

In a performance test, I want to bypass the influence of cache of linux system (including page cache/inode cache and so on). I have tried O_DIRECT flag, but it's turned out that direct I/O is still ...
8
votes
3answers
740 views

Compiling the Linux kernel

Just for the learning experience, I have recompiled the Linux kernel with different options, installed and booted from it. It was both instructive and straightforward. However, I was overwhelmed by ...
7
votes
2answers
13k views

Linux kernel hangs at 'Switching to clocksource tsc" on Pentium 4

Hardware: Dell Dimension 4500S : i845G, Pentium 4, stock + 2GB RAM and latest (circa 2002) BIOS update. I've been building a Linux system from source, so far it's LFS 7.0 by the book. The first ...
6
votes
4answers
11k views

How to search by content on Ubuntu

I'd like to search the entire server by content. (text file) When I try grep -rl "text here", it freezes. How would you do it? And how long does it usually take?
5
votes
8answers
6k views

Where is installed software stored in Linux? [duplicate]

Possible Duplicate: Where is a typical Linux program installed I'm new to Linux and I want to ask a bit more about packages. In Windows, I download an .exe file and install it. When I ...
5
votes
1answer
254 views

Kernel hacking methodology - how to find out where to hack the linux kernel

I have a throw-away cheap laptop I'd like to twiddle around, a Thinkpad SL 500. What bothers me are two leds, the one for wireless connectivity, and the one for hibernation, which don't light up at ...
4
votes
3answers
523 views

Pipe kernel messages to another process as they occur

I have an OLED screen on my laptop that I have configured to show status information. The current driver I have installed in Linux for it is able to display messages by sending them to a script as an ...
4
votes
4answers
199 views

What steps do I need to take to compile and install a Linux kernel?

What are the correct steps to compile a Linux kernel? Are these steps the same or different for different kernel versions i.e for 2.2, 2.4 and 2.6.
4
votes
2answers
464 views

Is it possible to boot a consumer i7 system with a Xeon processor and ECC memory?

I have read a couple of blog posts on the Internet that appear to imply one can boot at least some i7 motherboards with unbuffered ECC memory and a Xeon 43xx processor installed. I can boot my MSI ...
4
votes
1answer
4k views

`cat /proc/kmsg` outputs broken text

cat /proc/kmsg is convenient way to follow kernel messages. But the output is unreliable. Example: < eoyfl-o-ilF ilaltssI hwflssesJ a hwbctaealatv-psL hwmmr-sg()nc-l-TtssN oeOfso-eitr()so-l-iesQ ...
4
votes
1answer
696 views

Where did SELinux go?

I am compiling a new kernel, and want to enable SELinux but don't see it in menuconfig anywhere. The only framework under security options is Tomoyo.....so I ask, what happened to SELinux? Both ...
4
votes
2answers
54 views

How to remotely test the linux install CD for integrity

if you do, after the completing the test - it will eject the CD. and how are you going to reinsert the CD to complete your install? you're remote remember ??
3
votes
2answers
2k views

pinning process to a CPU

I wish to pin a process to a CPU1 in my dual CPU machine - how can I do it in Linux - any pointers ?
3
votes
2answers
1k views

Compile linux kernel for different machine

I am new to kernel development, and I have to compile a kernel with some specific features and then install it on some machines. The problem is that these machines are slow, and hence I want to ...
3
votes
3answers
2k views

Is it possible to make the OOM killer intervent earlier?

I try to tweak my development system to maximal reliability. I disabled swap, because for GUI usage it mostly renders the machine unresponsive in such a way not useable anymore. Nevertheless, if ...
3
votes
2answers
3k views

How to get a list of active drivers that are statically built into the linux kernel?

While I can use lsmod in order to show currently active kernel modules, how can I see which drivers are statically built into the kernel AND currently active?
3
votes
1answer
6k views

Where can I find the Linux kernel file?

Is there any common directory to find kernel file in all Linux distributions?if yes please tell me how to browse to the directory? Where can I find the Linux file in Ubuntu & RedHat operating ...
3
votes
3answers
2k views

Unmounting Detachable devices (eSATA,USB storage) in Linux

A detachable device like eSATA, USB drive can be abruptly removed (by simply pulling the plug). If there are open file handles on a partition, then this partitions won't unmount, i.e. the Linux ...
3
votes
1answer
165 views

Should I compile the linux kernel in the git repository itself?

This is about common practices. I have a git repository containing the linux kernel. Now I want to build this linux kernel. Should I copy the sources outside the git repository and then build the ...
3
votes
2answers
7k views

How do I set up grub2 with Xen?

I am booting a new Xen kernel and it all goes fine up until some point during the boot process when the machine reboots without warning. Unfortunately, I don't see errors flash up just before that ...
3
votes
2answers
2k views

lsmod and /proc/modules

I can get a list of modules using either lsmod or cat /proc/modules. Do the two approaches use the same mechanism to retrieve the modules? I want to know this as we could use it to find some hidden ...
3
votes
1answer
510 views

Microphone not working on Apple Macbook Air 1,1 (Early 2008; A1237) under Linux

I'm running Linux on the MBA. I can't make the microphone work. I test using alsamixer and arecord -Dhw -fdat -vv mic.wav together with aplay -Dhw -vv mic.wav It seems there is a problem with Linux ...
3
votes
1answer
280 views

enabling CONFIG_LIBIPW on kernel compiling

I need to enable CONFIG_LIBIPW=m on kernel 3.4.0 I see that IPW2100, IPW2200, and PCI needs to be enabled, but I could not find any clue where they are on the menuconfig. I read on ...
3
votes
2answers
2k views

Install VirtualBox on Ubuntu 12.04.1 (on [Samsung] Chromebook)

I have dual booted Ubuntu Linux 12.04.1 LTS on my Samsung Series 5 ChromeBook, and am trying to run/install Oracle VirtualBox (from the generic .run file downloaded from their website). However, every ...
2
votes
2answers
348 views

What does this macro mean in linux kernel code?

see i found one config file in which this are macro defined # # Input Device Drivers # CONFIG_INPUT_KEYBOARD=y # CONFIG_KEYBOARD_ADP5588 is not set CONFIG_KEYBOARD_ATKBD=y # CONFIG_KEYBOARD_QT2160 ...
2
votes
1answer
328 views

IPsec in the Linux Kernel

I have some issues (questions) related tot the Linux Kernel implementation of IPsec and it's user-space interface. The biggest question is which is the actual official project for the Linux Kernel ...
2
votes
1answer
123 views

Linux: Is it possible to know if my kernel has support for “policy routing” enabled?

I am following these instructions in order to configure multiple default routes for Linux (I am testing it on Ubuntu v12.04 and Kali v1.0.6), and the feature "policy routing" is requested enabled in ...
2
votes
2answers
2k views

Linux: Disable loopback interface from kernel

I know it is possible to bring down lo interface by doing ifconfig lo down. But is it possible to configure the kernel that the lo interface will simply not be available? Please note that I don't want ...
2
votes
1answer
871 views

nfs and cifs shares hanging from Linux

I've got a NAS (Dlink DNS-323) that I mount from my linux box. It used to work fine, and then I upgraded my distro (apt-get upgrade). I'm running Linux Mint Debian Edition. Current kernel is: ...
2
votes
1answer
667 views

ZFS distribution in Linux kernel? [closed]

If anyone has a better title for this question feel free to edit I am wondering about something related to the conflict between CDDL (Sun's license) and the GPL. Mainly pertaining to the reason ZFS ...
2
votes
1answer
105 views

can /usr/src be a sym link?

I want to store all source code of programs I have installed in /usr/src. However, due to size of the drive I made a sym link /usr/src that points to ~/src. That was nice. Unfortunately, that caused ...
2
votes
2answers
84 views

how do i switch custom kernels?

i have created and installed a new kernel in my ubuntu system, but now i have added a new system call and created a new kernel, how do i set this new kernel as the one the OS should boot from. dpkg ...
2
votes
1answer
78 views

Debian loses harddisk on bootup 4 times and then boots. Why?

Dmesg Dump: http://paste.debian.net/44975 at time 32.832045 That error is delaying my boot process significantly. Does anyone know what this is about? Devices: Maxtor IDE drive with new cable on ...
2
votes
1answer
432 views

Kernel bypass possible with non-specialised NIC?

Is it possible to perform kernel bypass and have a NIC send data to the user space (where I will write my network stack) with no copying, without having to purchase a specialised Solarflare etc NIC?
2
votes
1answer
1k views

Reliable HFS+ Journaled mount in any OS for ARMv6

I need an operating system for ARMv6 (Raspberry Pi) that can reliably mount HFS+ Journaled as read/write, with volume sizes up to 16TB. I've not been able to find details on how stable HFS+ Journaled ...
2
votes
1answer
297 views

GENTOO: disadvantages to using genkernel all?

I'm wondering, what are the disadvantages to using genkernel when I'm compiling a kernel in gentoo? Is it perfectly ok to use genkernel all in pretty much any situation, and skip this ...
2
votes
1answer
88 views

How is PAE implemented in Linux?

There are only 36 physical address lines but a page table entry is 64 bit long. How does the CPU check if the address is valid ? How does Linux OS map the same virtual address in different processes ...
2
votes
1answer
671 views

Out of space while bulding Linux kernel

I am trying to build Linux kernel. I am getting out of space after a while. I unpacked it in /usr/src directory. It seems I have plenty of space. Can you please let me know what can be done about it. ...
2
votes
0answers
55 views

Chipsee 7 inch LCD support in Linux kernel 3.14

Has anybody ported Chipsee 7 inch LCD on Linux kernel 3.14 or later ? Is there any patch available for the same ? If no patches any suggestion porting Chipsee LCD support from Linux kernel 3.8 to ...
2
votes
1answer
496 views

How do I stop rfkill module from hardblocking my wifi, without rfkill command?

I went into my BIOS the other day, didn't change anything, and rebooted. After this, my wifi was hardblocked. I looked online for solutions, and learned of the rfkill command. But I get rfkill: ...
2
votes
1answer
1k views

Linux kernel: getting ELAN touchscreen to work, USB debug related

This problem is actually known (ext: ELAN Touchscreen regression in recent 3.12's), but has no known solution up to kernel 3.13.6: [ 3844.533281] usb 2-7: new full-speed USB device number 91 using ...
2
votes
1answer
173 views

Why is INSTALL_MOD_STRIP not on by default?

I haven't compiled Linux kernels in a couple of years, and now that I started doing so again I discovered that modules are installed with debug symbols by default unless INSTALL_MOD_STRIP=1 is passed ...
2
votes
1answer
155 views

How to make Linux reliably boot on multi-cpu machines?

I've got two machines, one with 4x12 AMD Opteron cores (AMD Opteron(tm) Processor 6176), one with 2x8 Xeon cores (HT disabled; Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz). On both machines I experience ...
2
votes
1answer
435 views

Why is the kernel and the watchdogs consuming all the CPU?

I run a bunch of heavy user space processes on a powerful Xeon machine (32 virtual processors according to /proc/cpuinfo). The CPU load is normally around 30 and the machine feel responsive, but later ...
2
votes
0answers
169 views

In Linux Driver, how to disable a specific USB Device [closed]

Assume a USB devices is powered by USB bus. Sometimes the firmware in the USB device encounter a problem and can't recovery by itself. I have to unplug and plug the USB device from the host. Is there ...