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

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16
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2answers
6k views

Why does high disk I/O reduce system responsiveness/performance?

I never quite understood why high disk I/O slowed the system so much. It's strange to me because I would expect the slow-down to affect only those processes dependent on the hard/optical drive data, ...
5
votes
2answers
381 views

How to debug an inserted kernel module?

I would like to debug a loaded kernel module I don't have the source code to; I suspect it's a virus. Is there a way to feed it into GDB for analysis?
0
votes
3answers
1k views

Who wrote the “Linux kernel” (Linus Torvalds and his team)?

Who are the authors of the pure Linux kernel from scratch, which was integrated with GNU tools and formed the full GNU/Linux Operating system in the 1990s? I have read some wiki articles but I haven't ...
1
vote
1answer
501 views

System.map file update

I found that System.map file contains addresses of symbols. Does it involve system calls? I read that it is only updated when a new kernel is newly compiled. So does that means that except for a new ...
9
votes
1answer
1k views

What's the progress regarding improving system performance/responsiveness during high disk I/O?

Whenever there is high disk I/O, the system tends to be much slower and less responsive than usual. What's the progress on Linux kernel regarding this? Is this problem actively being worked on?
17
votes
4answers
10k views

What is the difference between the following kernel Makefile terms: vmlinux, vmlinuz, vmlinux.bin, zimage & bzimage?

While browsing through the Kernel Makefiles, i found these terms. So i would like to know what is the difference between vmlinux, vmlinuz, vmlinux.bin, zimage & bzimage?
5
votes
1answer
2k views

What are shmpages in laymans terms?

What exactly are shmpages in the grand scheme of kernel and memory terminology. If I'm hitting a shmpages limit, what does that mean? I'm also curious if this applies to more than linux
3
votes
1answer
363 views

Graphical boot-up screen lost after upgrading the kernel

I used the Ubuntu 10.10 alternate install CD to install Maverick to an encrypted partition on a USB stick. This worked perfectly, but after the first cycle of updates that took the kernel from ...
3
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1answer
449 views

`power/persist` file not found in USB device sysfs directory

The file /usr/share/doc/linux-doc/usb/persist.txt.gz mentions that the USB-persist capability can be enabled for a given USB device by writing 1 to the file persist in that device's directory in ...
3
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2answers
2k views

How to change the install path of my Linux Source tree?

I was trying to bring up my custom kernel. I did the following : $ make menuconfig && make modules && make modules_install && make install I would like to change the ...
4
votes
2answers
1k views

Can there be multiple kernels executing at the same time?

I know that Linux OS's are typically multi-programmed, which means that multiple processes can be active at the same time. Can there be multiple kernels executing at the same time?
11
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2answers
12k views

How to debug the input from an input-device (/dev/input/event*)

I have a IR reciver that is using the imon-driver and i would like to get it working with the kernel. Right now half of the keys on the remote (image) works, but an all important think like the ...
11
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3answers
19k views

what is the difference between spin locks and semaphores?

What are the basic differences between spin locks and semaphores in action?
6
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1answer
842 views

How to find the BSP sections in the Linux source code?

I would like to know how can i search for the BSP(Board Specific Packages) sections in the Linux Source code? All comments are welcomed.
7
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3answers
2k views

What happens after loading the linux kernel image into RAM

I just to want to know the flow of activities happening after loading the linux kernel image into the RAM after boot process.
6
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2answers
15k views

What is the difference between Non-preemptive, Preemptive and Selective Preemptive Kernel?

What is the difference between a "Non-preemptive", "Preemptive" and "Selective Preemptive" Kernel? Hope someone can shed some light into this.
5
votes
2answers
1k views

ZONE_NORMAL and it's association with Kernel/User-pages?

Above is presented a case where I have only 512 MB of physical memory. What I have read up so far, is that ZONE_NORMAL is mapped to the kernel virtual address space as shown. Essentially I have a ...
12
votes
1answer
6k views

What does the Virtual kernel Memory Layout in dmesg imply?

While going through the "Output of dmesg" I could see a list of values which i am not able to understand properly. Memory: 2047804k/2086248k available (3179k kernel code, 37232k reserved, 1935k ...
16
votes
1answer
580 views

How is new hardware support added to the linux kernel?

Imagine there's a company A that releases a new graphics adapter. Who manages the process that results in this new graphics adapter being supported by the Linux kernel in the future? How does that ...
11
votes
1answer
6k views

How can I configure cgroups to fairly share resources between users?

There used to be a kernel config option called sched_user or similar under cgroups. This allowed (to my knowledge) all users to fairly share system resources. In 2.6.35 it is not available. Is there a ...
60
votes
5answers
37k views

What are high memory and low memory on Linux?

I'm interested in the difference between Highmem and Lowmem: Why is there such a differentiation? What do we gain by doing so? What features does each have?
7
votes
2answers
752 views

Meaning of “rc5” in “linux kernel 2.6.37-rc5”

When I visited the kernel.org website to download the latest Linux kernel, I noticed a package named 2.6.37-rc5 in the repository. What is the meaning of the "rc5" at the end?
5
votes
3answers
4k views

How to generate initramfs image with busybox links?

Having been directed to initramfs by an answer to my earlier question (thanks!), I've been working on getting initramfs working. I can now boot the kernel and drop to a shell prompt, where I can ...
3
votes
1answer
484 views

Is PAE worth it when I have 4GB RAM?

I have 4GB RAM installed on my machine, and I'm considering using all of it (IE, installing PAE-enabled kernel). I heard there's a performance penalty for this, so I wanted to know about other's ...
4
votes
3answers
861 views

Debugging ethernet before NFS boot

I'm trying to boot Linux from U-boot on an embedded ARM board using a filesystem on a remote machine served via NFS. It appears that the ethernet connection is not coming up correctly, which results ...
6
votes
1answer
1k views

Wi-Fi constantly disconnects

Using either NetworkManager or Wicd to manage wireless networking on my Wi-Fi-powered laptop, too often I get randomly disconnected, and I see these messages on /var/log/syslog: Dec 10 05:21:26 ...
4
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2answers
10k views

How to create .ko files in Linux

I have written one driver for one device in Linux. How can I create (using gcc) a .ko file so that I can insert it into the kernel?
1
vote
0answers
225 views

kernel compilation error [duplicate]

Possible Duplicate: Kernel can't find /dev/sda file during boot I got the following errors after new kernel compilation (linux-2.6.25.tar.bz2) mount: could not find filesystem ...
6
votes
4answers
4k views

How many cores can Linux kernel handle?

I'm interested in theoretical limits, perhaps with examples of systems having huge numbers of CPU's.
8
votes
1answer
387 views

Why should a user program mess with kernel space?

I'm not even sure what the problem is, but I'm talking about the kernel attack described here. Down this list of comments somebody asked about renicing the process. The trick didn't improve the ...
2
votes
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
447 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
828 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
297 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
387 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
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2answers
640 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
447 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
764 views

Contents of /proc

Is there a site someplace that lists the contents of /proc and what each entry means?
3
votes
2answers
542 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
8k 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
397 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
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1answer
726 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
839 views

Does the Linux PreemptRT patch benefit desktop users?

Does the PREEMPT_RT patch (real-time kernel) have any benefit for regular desktop users?