Modules vs Built-in Re: [wplug] basic hosting

[Patryk Laurent]

Henry,

Actually, I just read about this in the O'Reilly book "Understanding the
Linux Kernel" which in fact has an appendix on modules.   It turns out
that all references are resolved when the module is loaded so the code
acts just as if it was statically linked into the kernel and there is no
performance penalty in JMPing to it.

"A module is an object file whose code can be linked to (and unlinked
from) the kernal at runtime.  [...] Once linked in, the object code of a
module is equivalent to the object code of the statically linked
kernel.  Therefore, no explicit message passing is required when the
functions of the module are invoked."

The footnote points out where the only penalty is:  in linking and
unlinking the module.

Modules rock.

Patryk


On Sun, 2002-12-15 at 08:31, Henry Umansky wrote:
> Does anyone know if there is a speed difference of making kernel modules 
> built-in to the kernel??  For instance, because I use iptables all the 
> time, would it be beneficial to making iptables built into the kernel 
> instead of making it a module (iptables.o)??
> 
> Henry Umansky
> hmust2 [at] pitt [dot] edu
> http://www.pitt.edu/~hmust2
> 
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