Re: System Call

From: Josef Moellers (josef.moellers_at_fujitsu-siemens.com)
Date: 12/20/04 

Date: Mon, 20 Dec 2004 16:17:08 +0100

Kasper Dupont wrote:
> Josef Moellers wrote:
>
>>but the kernel has the penalty of an indirection
>>when calling "Functions exported from a module"!
>
>
> I don't think that is even possible.
>

Then what's the use of a module exporting functions if there's noone who
can call them?

But you're right: the kernel will not be able to call a function merely
because it's exported (the addresses will not automagically find their
way into the kernel _code_), but those functions exported will be
usually be registered somewhere (e.g. by hooking up to the
scsi-mid-layer or the block-device-layer code) and then called by kernel
code.

I.e. access from the kernel to code within a module has the penalty of
an indirection. 

-- 
Josef Möllers (Pinguinpfleger bei FSC)
	If failure had no penalty success would not be a prize
						-- T.  Pratchett

Relevant Pages

  • Re: [PATCH] Athlon Prefetch workaround for 2.6.0test6
    ... >> the code size penalty is still there for CPUs which don't need it. ... You can build a 386 kernel which will run fine on K7 if you are too ... send the line "unsubscribe linux-kernel" in ...
    (Linux-Kernel)
  • Re: HTT on Atom (Was: FreeBSD 8.0 and Atheros AzureWave wireless chipset)
    ... Is there really no penalty? ... With HZ=1000 there are double the clock ... interrupts to be serviced at least. ... Using -j3 in make kernel, the kernel is built in just about 40 minutes. ...
    (freebsd-questions)
  • Re: Is 386 processor still supported?
    ... Certainly it adds some bloat to the kernel, ... Nobody normally builds for 386 (and you need the big FPU emulator etc too ... and pay a big penalty for the lack of working WP bits) so it wouldn't be ...
    (Linux-Kernel)
  • Re: System Call
    ... > but the kernel has the penalty of an indirection ... Kasper Dupont ...
    (comp.os.linux.development.system)
  • Re: Is 386 processor still supported?
    ... software maintainers. ... Certainly it adds some bloat to the kernel, ... and pay a big penalty for the lack of working WP bits) so it wouldn't be ...
    (Linux-Kernel)