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

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2
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2answers
159 views

Why does truncate fail for sizes above 2043G in ext3?

Why does this work: truncate -s 2043G foo ...while this fails: truncate -s 2044G foo Why 2043 gigabytes, of all values?
4
votes
1answer
436 views

Are there any Workload Management subsystems for Linux?

Asked this on superuser, got no response: Can anyone tell me of the status/state of WLM (Workload Management) kernel scheduler systems in Linux? Alternatively, any user-space process goal-based load ...
8
votes
1answer
1k views

Why does the linux kernel use linux-libre code to get rid of binary blobs?

I ask this question because I'm curious as to whether there is some sort of performance advantage offered from the binary blobs that are in the Linux kernel. Since many of these blobs have been ...
9
votes
4answers
1k views

GRUB on USB Drive — adding OSes

Some Background: Coming from a largely Windows background (though I'm familiar with Ubuntu, etc.) and using a Windows 7 machine to complete this task Have gotten GRUB installed successfully to the ...
1
vote
1answer
809 views

Example for kernel timer Implementation in Linux

Could you please give any basic example of a kernel timer (start_ktimer) implementation in Linux?
3
votes
1answer
296 views

Migrating from tp_smapi to 'normal' ACPI support in 2.6.36

I used zen kernel patchset for a long time which included tp_smapi patch. Recently in zen-stable tp_smapi was removed as "We no longer need tp_smapi as of 2.6.36 - the in-kernel thinkpad acpi support ...
4
votes
3answers
375 views

Kernel debugging

I would like to study the flow of some linux device drivers and some minimal flow of kernel (threading cum context switching and interrupt management). How can I debug the linux kernel? What are the ...
0
votes
2answers
630 views

Installing new kernel (by commandline) as side of old kernel and effective configuration of ' menuconfig'

I need to install another kernel (2.6.34) into my fedora machine (x86) and i need to show the old and new boot up options in the boot menu (both new and old kernel) I have downloaded the new kernel ...
4
votes
1answer
434 views

What does “warning: override: VZ_FAIRSCHED changes choice state” mean?

I am building a Linux kernel, via the Debian linux-2.6 source package. Now there's CONFIG_VZ_FAIRSCHED=y in a sub-config, which gets merged into the final .config, where apparently also "y" gets ...
4
votes
1answer
2k views

Kernel segmentation fault (core dumped), how to diagnose? [closed]

I have a fedora 13 x64 box I use at home for a storage server. I use sshfs to mount my music from home and listen at work, I run my irssi client in screen on it for freenode communication and lately ...
1
vote
3answers
2k views

vga_switcheroo not in /sys/kernel/debug in 2.6.35-22 (kubuntu maverick)

I have a sony VPCZ12 laptop. It has those dual video cards that are a pain to get working in linux. The new 2.6.35 kernel is supposed to support that with the vga_switcheroo module which is supposed ...
1
vote
3answers
89 views

What's up with the metadata in the source? Are there tools for it?

I'm comparing two different kernel versions (one official, one from a manufacturer); there are thousands of file whose only difference is in metadata in the files. The metadata looks like '$:Key: ...
13
votes
3answers
750 views

Contents of /proc

Is there a site someplace that lists the contents of /proc and what each entry means?
3
votes
2answers
540 views

Will enabling Hyper-Threading create two virtual half-speed processors?

If I enable Hyper-Threading for my netbook which has an Intel Atom (1.6 GHz) will the kernel see two virtual 800 MHz processors?
4
votes
3answers
1k views

Recompile Kernel to Change Stack Size

I need to recompile my kernel on RHEL WS5 with only two changes. Change stack size from 4k to 8k Limit usable memory to 4096. How do I recompile the kernel without changing anything else but ...
8
votes
5answers
7k views

Is it possible to put root in LVM without using initrd?

I have just set up a Gentoo base system (which means I can boot and log in and do stuff with it now). My root partition is in an LVM2 virtual group (with a separated /boot partition). In order to boot ...
3
votes
2answers
395 views

Buffer overflow attacks

I just learnt today in a Distributed Systems class that there is an address space allocated for every user by the kernel, and if a user wants to get the su privilege, he needs to shift to the kernel ...
7
votes
1answer
5k views

What is the loopback interface

What is the loopback interface and how does it differ from the eth0 interface? And why do I need to use it when mounting an ISO or running a service on localhost?
6
votes
1answer
717 views

Patching Linux kernel on-line (i.e. without rebooting)

Sorry - I don't remember the exact name. I know there is mechanism to patch the kernel at runtime by loading modules without need of the reboot as long as the structures involved are not affected. It ...
3
votes
2answers
824 views

Does the Linux PreemptRT patch benefit desktop users?

Does the PREEMPT_RT patch (real-time kernel) have any benefit for regular desktop users?
12
votes
5answers
5k views

Benefit of kernel module compiled inside kernel?

What's the benefit of compiling kernel modules into the kernel (instead of as loadable modules)?
2
votes
1answer
327 views

Kernel memory allocator patch

Is there any patch for Linux kernel to use different memory allocators, such as ned allocator or TLSF allocator?
11
votes
6answers
7k views

Compiling GNU/Linux with -O3 optimization

It's said that compiling GNU tools and Linux kernel with -O3 gcc optimization option will produce weird and funky bugs. Is it true? Has anyone tried it or is it just a hoax?
11
votes
2answers
2k views

Heavy write activity on SSD nukes system performance

I've noticed that when I do heavy write applications, the whole system slows down. To test this further I ran this to do a (relatively) low-CPU, high disk activity: john -incremental > file_on_SSD ...
2
votes
1answer
396 views

Sometimes no sound in flash videos after boot?

Sometimes after I boot up the machine, I get no sound in flash videos. First I didn't know why it was happening, but as I read a few articles here and there, I found out it was because of my USB ...
8
votes
6answers
3k views

How to find information about the system/machine in Unix?

I have always found it difficult to find information about the system itself in Unix, whether it be Which OS I am using (version number and all, to compare it with the latest available builds)? ...
2
votes
8answers
928 views

Oldest Linux machine you still run [closed]

What is your oldest machine you ever installed Linux on and currently still run? What are the specs, kernel version or distro, and for what purpose?
34
votes
7answers
23k views

Linux Kernel: Good beginners' tutorial [closed]

I'm interested in modifying the kernel internals, applying patches, handling device drivers and modules, for my own personal fun. Is there a comprehensive resource for kernel hacking, intended for ...
6
votes
1answer
402 views

Linux kernel 2.6 on ARM

I have compiled and installed the 2.6 kernel on an ARM board. I am using the ARM mini2440 board. I would like to know if there is already a way to access the General Purpose I/O port pins? Or will ...
70
votes
12answers
11k views

What is the benefit of compiling your own linux kernel?

What benefit could I see by compiling a Linux kernel myself? Is there some efficiency you could create by customizing it to your hardware?
10
votes
3answers
1k views

What does it mean when code is executed in [kernel|user] mode?

The title says everything.
8
votes
3answers
690 views

Why does it makes sense to cache swap?

It sounds quite counter-productive to me to cache pages that are swapped out. If you swap pages in, what is the advantage to first cache them in memory, only to have to than move them to the right ...
4
votes
3answers
2k views

How can I tweak the kernel for total swap out?

I would like to deploy the following swapping policy: By default all pages in memory should also be in swap space. When a page in memory is changed (i.e. dirty), the page should be written out as ...
5
votes
1answer
892 views

Is it safe to disable OOM killer in a web server/reverse proxy?

I have Linux machine dedicated to serving static contents and PHP pages with Apache. Apache also work as a reverse proxy in a subdomain. I moved the PostgreSQL database to another Linux machine. Is ...
26
votes
12answers
3k views

How can I tweak my Linux desktop to be more responsive?

I have the experience that Linux works fine until the physical memory is exhausted. As soon as swap space is used the performance is severely degraded and the GUI becomes unresponsive. This problem ...
8
votes
3answers
3k views

How should I configure grub for booting linux kernel from a USB hard drive?

I have a laptop hard drive in an external enclosure which I use as a large pendrive. For an added twist, I have installed Linux on it, so I can boot any machine with my distribution of choice (e.g. ...