monolithic kernel

TjPhysicist · 2009-06-24 07:27:04

First off I am aware this is a subject that can quickly get into a flame war (comp.os.minix discussion comes to mind). Anwyas on to the matter at hand:

As i understand it Linux is basically a monolithic kernel with (optional?) modular support. I have been told that originally linux and other kernels were basically monolithic in structure no modules either. My question here is two fold:

a. How many of you use a monolithic linux kernel (i.e. you have disabled module support while compiling), and why.
b. What are the advantages that you have noticed with/without modular support.

As someone who is slowly getting into kernel hacking, I have tried it all from everything possible as modules to fully monolithic (my current configuration is the latter). I am briefly aware of pro's and con's on both sides, I want to get some input from the arch community about this though.

The main reason behind this post is to see how many of you out there compile with no modules of course, and your experiances with said kernel.

ngoonee · 2009-06-24 08:17:01

Would there be very many? Would a monolithic kernel be able to use VirtualBox PUEL, or the nvidia/ati binaries? I'd think that alone would rule out a sizeable number of users.

For myself, I always compile modules, as an nvidia user. Read somewhere that the speed of context switching means built-in modules may not give that much of a boost, if any.

PJ · 2009-06-24 09:06:44

The only advantage I can find for not compiling module support is that it will be a lot harder to insert a rootkit in the system, other than that I don't see any real advantages. I haven't compiled kernels in years, but when I last did it used to be a lot easier to do it without module support and that is actually the last time I did compile my own kernel. Nowadays I am pretty happy with the stock kernel that comes with Arch Linux.

Themaister · 2009-06-24 09:09:13

I see no reason to compile everything into the kernel. Compiling the filesystem/sata-drivers into the kernel is handy, since you won't need an initramfs (but the gain is often abysmal).

davvil · 2009-06-24 10:14:13

Do not confuse "monolithic" in a operating system design context with monolithic in the sense of "non-modular". From a design point of view, Linux is a monolithic kernel, independently if you compile it with or without modules support. The kernel is a big "binary blob" that runs in privileged mode. Compare this with a microkernel architecture (e.g. minix), where the filesystem, the scheduler and many other services are separate processes that run in unprivileged mode.

TjPhysicist · 2009-06-24 16:26:10

@davvil: o yea i understand the difference, lol. thanks for confirming that.

Ranguvar · 2009-06-25 01:49:09

davvil is right. But modules vs a solid kernel? Modules are nice for distro defaults, because you can add them in separate packages, etc. When you compile your own kernel, you can tune for exactly what you need, so unless you want to enable/disable certain functionality, there's no reason not to compile the modules in. I think there's some other benefits, but I've forgotten.

von_Wanderlust · 2009-06-25 15:10:23

PJ wrote:

The only advantage I can find for not compiling module support is that it will be a lot harder to insert a rootkit in the system

Funny you mention that, I saw on LWN.net today that 2.6.31 will allow you to block loading of modules through sysctl.

DevoidOfWindows · 2009-07-03 08:27:48

I will load important things into the kernel, but everything else is a module. There are some things what will kill my system at boot if I don't compile as a module (e.g., AGP/Radeon).

Last edited by DevoidOfWindows (2009-07-03 08:29:20)

combuster · 2009-07-03 08:33:53

Same here, basic drivers needed for my laptop are going into kernel but I don't want to loose support for various external devices by not building them at all and I'm not too keen on growing my bzImage with that stuff so I compile them as modules...

Just now I'm compiling 2.6.30.1

Last edited by combuster (2009-07-03 08:34:38)

Army · 2009-07-03 09:53:49

Things like the ipw2200 driver NEED to be a module, because first the firmware has to be loaded, then the module can be loaded.

Misfit138 · 2009-07-03 17:53:25

The Linux kernel is monolithic.
The post title should be changed to "Static Kernel or Modular" in order to more accurately convey what you are describing.

darthaxul · 2009-07-04 21:16:41

When Linus Torvalds decided to build a "free Unix for the 386″ he stripped away Tanenbaum's layered micro-kernel and hardwired Intel's approach to interrupt management directly into what has since become the largest monolithic kernel still in use....LOL

monolithic kernels are scary.
I'm gonna switch to micro or at least something else here pretty soon.
...ok im gone for good.

Last edited by darthaxul (2009-07-04 22:25:54)

Arch Linux

#1 2009-06-24 07:27:04

monolithic kernel

#2 2009-06-24 08:17:01

Re: monolithic kernel

#3 2009-06-24 09:06:44

Re: monolithic kernel

#4 2009-06-24 09:09:13

Re: monolithic kernel

#5 2009-06-24 10:14:13

Re: monolithic kernel

#6 2009-06-24 16:26:10

Re: monolithic kernel

#7 2009-06-25 01:49:09

Re: monolithic kernel

#8 2009-06-25 15:10:23

Re: monolithic kernel

#9 2009-07-03 08:27:48

Re: monolithic kernel

#10 2009-07-03 08:33:53

Re: monolithic kernel

#11 2009-07-03 09:53:49

Re: monolithic kernel

#12 2009-07-03 17:53:25

Re: monolithic kernel

#13 2009-07-04 21:16:41

Re: monolithic kernel

Board footer