Questions tagged [kernel]

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

The kernel of every operating system builds the bridge between the application and the actual processing on the hardware level.

A typical Unix kernel is responsible for:

  • CPU Program execution
  • Memory Management
  • Processes (Scheduling, Synchronization, Interprocess Communication)
  • Signals (Exceptions, Interrupts)
  • Filesystems (Virtual, Block)
  • I/O Architecture (Devices, Files, Networking)

The two most common architectures for Unix kernels are:

  • Monolithic kernel: Every kernel layer is integrated in into the whole kernel and therefore runs in kernel space. Every user application has to access the kernel through a high-level interface. Most Unix(-like) kernel follow this approach.

  • Microkernel: Only the essential parts of the kernel run in kernel space. Applications are allowed to directly address different kernel layers (device drivers, filesystems, ..).

Linux

The kernel is a Unix-like kernel initially created by Linus Torvalds in 1991 and now is maintained by developers around the world.

Linux kernel compilation

Linux kernel internals

Further reading

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What is the difference of kernel/distribution's release and version?

I use the following command to see the name, release and version of a kernel. -bash-4.1$ uname -s Linux -bash-4.1$ uname -r 2.6.32-279.el6.x86_64 -bash-4.1$ uname -v #1 SMP Wed Jun 13 18:24:36 EDT 2012 What is the difference and relation between…
Tim
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What does it mean when code is executed in [kernel|user] mode?

What does it mean when code is executed in kernel or user mode?
Luc M
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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 situation (the machine still runs in a very sluggish…
phunehehe
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User space to kernel space transition

Both physically (hardware, rings) and logically (software), what is user space to kernel space transition? And vice versa. Or more generally what goes on when there is a "space" (or ring) transition taking place? And what makes it costly (one of the…
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What does it mean to install a kernel?

What does it mean to install a new version of the kernel. My Linux box gave me this message when I was updating, NOTE, 3.8.13 was the last maintained maintenance release by Greg Kroah-Hartman. It is recommend to move on to linux310-series. What…
Jay
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What potential ills can be brought by 'deleting' a live kernel?

I recently deleted my active Linux kernel and continued using the system as if nothing drastic happened. Are there any side-effects to deleting the Linux kernel that's currently in use? What about other non-Windows kernels?
tshepang
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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 hardware I obviously do not have. Is there a way to…
ThiefMaster
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How can Kernel 4.0 patch the system rebootless?

I've seen that new functionality mentioned in Linux kernel 4.0 was the ability to update without a reboot. Does this mean I can use my system with my application going, and the update will have no effect whatsoever on the execution of the current…
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Is there a way to update kernel version without rebooting?

I am running an update which can update the kernel to the latest version, After that I am installing a few drivers but they get loaded on the old kernel since. Upon rebooting, those drivers go missing for the new updated version. Is there any way to…
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How can I locate a specific kernel source code on my machine

I want to locate the kernel's signal.c source code on my machine, to study the differences (if exist) between what I have and this source code. I tried following this post suggestion, but didn't get far. I guess I need more specific instructions.…
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Removing/Purging linux-headers-3.16.0-30-generic, but apt-get wants to install linux-headers-3.16.0-50-generic

The command I am running is: apt-get purge linux-headers-3.16.0-30 linux-headers-3.16.0-30-generic linux-image-3.16.0-30-generic linux-image-extra-3.16.0-30-generic linux-libc-dev --assume-yes However, during the command,apt-get wants to install…
Minh La
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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 address space. Is this the basis for buffer…
tsudot
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What is the difference/relation between kernel name and OS name?

What is the difference/relation between kernel name and OS name? Are they always the same thing? For example, I am puzzled at the outputs: -bash-4.1$ uname -s Linux -bash-4.1$ uname -o GNU/Linux What is difference between "GNU/Linux" and "Linux"?
Tim
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What is user address space and what is it's purpose?

I am reading about processes. I came across a topic "How a process is created" wherein I encountered the following :- The process image as viewed by the kernel runs in its own user address space – a protected space which can't be disturbed by other…
Ankit
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What "r8169 can't disable ASPM" means and how should I fix it?

I found this in my kernel logs: kernel: r8169 0000:02:00.0: can't disable ASPM; OS doesn't have ASPM control What does it mean and how should I fix it? lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu…
Adrian
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