Subject: Re: Kernel Hacker want-a-be.
To: Andrew Brown <firstname.lastname@example.org>
From: Ben Harris <email@example.com>
Date: 04/17/2000 18:48:04
On Mon, 17 Apr 2000, Andrew Brown wrote:
> >To my mind, the interesting thing about the kernel is that it's much like
> >writing for a different system. You're still writing in C, but what looks
> >like pre-emptive multitasking from above suddenly turns out to be
> >co-operative, and virtual memory turns out to be all too real. Half your
> >friends from libc (like malloc() and free()) turn out to have different
> >arguments, too.
> and null pointers give you a "different kind" of core dump. :)
*grin* Yes, like causing SWI (system call) instructions to enter the page
fault handler. That was a silly one.
> >As for how to get to know the kernel, try porting it to new hardware. The
> >past few months has taught me more about how the kernel works than any
> >amount of source browsing could have. Writing new device drivers for an
> >existing port is a good way to get started, but spares you the really _fun_
> >bits of kernel programming. Understanding fork() and exit() from the inside
> >is a rather mind-bending experience.
> this is something that i *wish* i had the time and expertise to do.
> oh...and the hardware. i know there are plenty of platforms left out
> there...i just don't have any of them. :)
Expertise can be learned. Hardware is free (if it's old enough). Time
and documentation are the killers.
> one thing that would be "helpful" in generic porting efforts would be
> a list of the things (functions, macros, defines and constants, etc)
> that the md code actually provides. is there such a list somewhere?
I found that I could get a pretty comprehensive list by compiling a kernel
for a new architecture and seeing where it fell over. I agree that some
documentation of that layer is needed, but keeping it up to date is liable
to be painful.
Actually, just a list of what belongs in which header files would be
Unix Support, University of Cambridge Computing Service.
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