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

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4
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3answers
750 views

Preloading the OOM Killer

I don't have any swap partition/file on my machine, and only 2GB of RAM. Sometimes it happens that the memory gets saturated by some process (Xorg+browser+compiler+...) and the system hangs ...
25
votes
1answer
38k views

How is a message queue implemented in the Linux kernel?

I would like to know how Message Queues are implemented in the Linux Kernel.
15
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4answers
569 views

How do I learn what I can do with /proc and /sys

I'd like to know more about the advanced uses of the /proc and /sys virtual filesystems, but I don't know where to begin. Can anyone suggest any good sources to learn from? Also, since I think sys has ...
0
votes
2answers
354 views

FreeBSD's kernel is 'locked'?

I happened to talk to a Mac Genius on the subject of viruses. He mentioned that the FreeBSD kernel on which the Mac OS is based is 'locked' and therefore no viruses can ever harm my Mac. I didn't ...
2
votes
2answers
1k views

Questions on Linux kernel internals [closed]

I was reading "Linux device drivers, 3rd edition" and faced a few kernel items I don't quite understand. Hope gurus on this forum will help me out. Does the Linux kernel internally operate with ...
8
votes
2answers
3k views

How do I debug a kernel module in which a NULL pointer appears?

I have a custom kernel module that I compiled from this patch that adds support for the logitech G19 keyboard among other G series devices. I compiled it just fine against Ubuntu's maverick kernel's ...
4
votes
1answer
378 views

Changes to input_get_keycode function in linux kernel (input/input.c)

I'm working on building a kernel module for an input device, and I noticed that in the module source, there's a couple calls to input_get_keycode(data->input_dev, scancode, &keycode); When I ...
1
vote
2answers
853 views

S3 sleep problems — nVidia or Intel H67 (Sandy Bridge motherboard) issue?

I have a new Sandy Bridge i5-2500 and Intel H67 motherboard. As the onboard video didn't work, I put in an older 8600 gts graphics card. However, the S3 suspend won't work (and I can't test without ...
15
votes
5answers
13k views

Use of O_DIRECT on Linux

If this question is too programmer oriented, let me know. I wonder if there are people familiar with the O_DIRECT flag for the open() system call on Linux 2.6? Linus disparages its use, however high ...
26
votes
8answers
11k views

How does Linux kernel compare to microkernel architectures?

I read once that one advantage of a microkernel architecture is that you can stop/start essential services like networking and filesystems, without needing to restart the whole system. But considering ...
95
votes
4answers
65k views

How do I read from /proc/$pid/mem under Linux?

The Linux proc(5) man page tells me that /proc/$pid/mem “can be used to access the pages of a process's memory”. But a straightforward attempt to use it only gives me $ cat /proc/$$/mem /proc/self/...
3
votes
1answer
283 views

Can't shutdown mandriva 2010.2

I can't seem to shutdown my machine from mandriva,I have to restart to shut it down from GRUB it says "System Halted" and just freezes there I'm using the x86_64 GNOME version I've already asked on ...
1
vote
1answer
820 views

Select YeAH-TCP like congestion control algorithm to configure kernel

I'm configuring/compiling the 2.6.37 kernel and I want select YeAH-TCP like default congestion control algorithm but, although I enable this option (CONFIG_TCP_CONG_YEAH), it doesn't show in the ...
5
votes
1answer
2k views

Usage of inb, inl, inw to access kernel space from user space

What are some user space examples of using inb, inl, and inw to access kernel space in Linux?
5
votes
1answer
318 views

Why do I need ntfs-3g when I have already enabled NTFS support in the kernel?

When configuring the kernel I see an option to add read-write support for NTFS. Then when mounting my NTFS partition I still have to install ntfs-3g and pass ntfs-3g as the type. I thought if I add ...
25
votes
4answers
39k views

How is an Interrupt handled in Linux?

I just know that Interrupt is a hardware signal assertion caused in a processor pin. But I would like to know how Linux OS handles it. What all are the things that happen when an interrupt occurs?
4
votes
1answer
948 views

More doubts in bzImage

The description of the bzImage in Wikipedia is really confusing me. The above picture is from Wikipedia, but the line next to it is: The bzImage file is in a specific format: It contains ...
9
votes
2answers
874 views

Install new kernel in PowerPC debian

I compiled a new kernel image on x86 using cross compiler with these commands (source): $ cp arch/powerpc/configs/pmac32_defconfig .config $ make ARCH=powerpc menuconfig $ make ARCH=powerpc ...
18
votes
2answers
7k 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
420 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?
1
vote
3answers
2k 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
549 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?
25
votes
4answers
17k 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?
6
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
373 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 2.6.35-...
3
votes
1answer
514 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 /sys/...
3
votes
2answers
3k 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 ...
5
votes
2answers
2k 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?
12
votes
2answers
16k 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
votes
3answers
23k views

what is the difference between spin locks and semaphores?

What are the basic differences between spin locks and semaphores in action?
6
votes
1answer
940 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.
8
votes
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.
7
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2answers
20k 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 512 ...
16
votes
1answer
8k 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 ...
17
votes
1answer
638 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
7k 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 ...
67
votes
5answers
49k 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?
10
votes
2answers
1k 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
5k 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 ...
4
votes
1answer
527 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
962 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 ...
5
votes
2answers
13k 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
226 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 '/dev/...
7
votes
4answers
6k 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
416 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
166 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
2answers
593 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 ...