Subject: monoholitic, hybrid or not monoholitic?

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hello world,

i've invested a couple of hours to find a correct description of the
linux kernel achritecture. most books or litretures (in general) are
talking about a monoholitic kernel (incl. linux kernel development -
robert love and understanding the linux kernel - oreilly). i also asked
google an read the kernel.org faq.

the kernel were mostly descripted as monoholitic. but some sources means
that the linux kernel is not really monoholitic because of the feature
of loading kernel modules. some pages are talking about a "hybrid
kernel" which means that the kernel is a glue one, a little bit of
monoholitic and a little bit not.

so i would like to receive detailed information where i can read a
correct description of course you can also post your comments here (if
allowed). by the way, yes i've read the "tanenbaum" reffering monoholitc.

thanks a lot in advanced,
patrick

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2004-09-15 13:06:32

by Luca Ferroni

[permalink] [raw]
Subject: Re: monoholitic, hybrid or not monoholitic?

Il Wed, 15 Sep 2004 13:27:25 +0200, Patrick Kiwitter- Mailinglist <[email protected]> ha scritto:

> the kernel were mostly descripted as monoholitic. but some sources means
> that the linux kernel is not really monoholitic because of the feature
> of loading kernel modules. some pages are talking about a "hybrid
> kernel" which means that the kernel is a glue one, a little bit of
> monoholitic and a little bit not.
>

I think Linux kernel should be considered monoholitic anyway,
because, even it can load kernel modules, they execute themselves
in kernel privileged space.
You can compile some kernel parts as modules,
so they belong to the Linux core, the only difference is that they
are loaded on demand implying all benefits and disadvantages we know.

Bye
Luca

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They'll never steal us our .... FREEDOM!!!
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2004-09-15 14:20:26

by Matt Kavanagh

[permalink] [raw]
Subject: Re: monoholitic, hybrid or not monoholitic?

On Wed, Sep 15, 2004 at 01:27:25PM +0200, Patrick Kiwitter- Mailinglist wrote:
> Hash: SHA1
>
> hello world,
>
> i've invested a couple of hours to find a correct description of the
> linux kernel achritecture. most books or litretures (in general) are
> talking about a monoholitic kernel (incl. linux kernel development -
> robert love and understanding the linux kernel - oreilly). i also asked
> google an read the kernel.org faq.
>
> the kernel were mostly descripted as monoholitic. but some sources means
> that the linux kernel is not really monoholitic because of the feature
> of loading kernel modules. some pages are talking about a "hybrid
> kernel" which means that the kernel is a glue one, a little bit of
> monoholitic and a little bit not.
>
> so i would like to receive detailed information where i can read a
> correct description of course you can also post your comments here (if
> allowed). by the way, yes i've read the "tanenbaum" reffering monoholitc.
>
> thanks a lot in advanced,
> patrick
>
I'd tend towards monolithic because the modules (as mentioned) run in kernel
space; but it's not a cookie-cutter case. Things are implemented in userspace
that provide functionality normally included in the kernel; udev springs to
mind, even if it is not the predominant solution.

2004-09-16 00:29:07

by Tommy Reynolds

[permalink] [raw]
Subject: Re: monoholitic, hybrid or not monoholitic?

Uttered Matt Kavanagh <[email protected]>, spake thus:

> > the kernel were mostly descripted as monoholitic. but some sources means
> > that the linux kernel is not really monoholitic because of the feature
> > of loading kernel modules.
> I'd tend towards monolithic because the modules (as mentioned) run in kernel
> space.

These discussions are taking the wrong viewpoint. The difference
between "monolithic" and "modular" kernels refers to their *internal*
organization, not a cosmetic *packaging* decision.

Linux is a monolithic kernel because one kernel routine can call
another directly, without intervention of any message passing
overhead.

Linux modules are simply packaging exercises that allow some code
_not_ originally linked into the kernel image to be grafted into an
executing kernel image. Once installed, kernel modules can reference
other kernel resources with, again, a straight subroutine reference
without any message passing intervention.

All else is quibbling about the color of the ribbon used to wrap up
the module code ;-)

HTH.
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2004-09-16 01:14:30

by Kurt Wall

[permalink] [raw]
Subject: Re: monoholitic, hybrid or not monoholitic?

On Wed, Sep 15, 2004 at 07:22:31PM -0500, Tommy Reynolds took 69 lines to write:

[mumble]

> All else is quibbling about the color of the ribbon used to wrap up
> the module code ;-)

Or what color to paint the bike shed.

Kurt
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