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References: <20051003004442.GL6290@lkcl.net> <20051003075000.28A8C13ED9@rhn.tartu-labor> <20051003180858.GA8011@csclub.uwaterloo.ca>
Content-class: urn:content-classes:message
Subject: Re: what's next for the linux kernel?
Date: Mon, 3 Oct 2005 14:28:59 -0400
Message-ID: <Pine.LNX.4.61.0510031416560.24845@chaos.analogic.com>
Thread-Topic: what's next for the linux kernel?
Thread-Index: AcXISFW3E/wJ6m/dRfOTCEJ8etOpPQ==
From: "linux-os \(Dick Johnson\)" <linux-os@analogic.com>
To: "Lennart Sorensen" <lsorense@csclub.uwaterloo.ca>
Cc: "Meelis Roos" <mroos@linux.ee>, <lkcl@lkcl.net>,
       <linux-kernel@vger.kernel.org>
Reply-To: "linux-os \(Dick Johnson\)" <linux-os@analogic.com>
Sender: linux-kernel-owner@vger.kernel.org
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On Mon, 3 Oct 2005, Lennart Sorensen wrote:

> On Mon, Oct 03, 2005 at 10:50:00AM +0300, Meelis Roos wrote:
>> LKCL>  the code for oskit has been available for some years, now,
>> LKCL>  and is regularly maintained.  the l4linux people have had to
>>
>> My experience with oskit (trying to let students use it for OS course
>> homework) is quite ... underwhelming. It works as long as you try to use
>> it exactly like the developers did and breaks on a slightest sidestep
>> from that road. And there's not much documentation so it's hard to learn
>> where that road might be.
>>
>> Switched to Linux/BSD code hacking with students, the code that actually
>> works.
>
> Can oskit be worse than nachos where the OS ran outside the memory space
> and cpu with only applications being inside the emulated mips processor?
> Made some things much too easy to do, and other things much to hard
> (like converting an address from user space to kernel space an accessing
> it, which should be easy, but was hard).
>
> I suspect most 'simple' OS teaching tools are awful.  Of course writing
> a complete OS from scratch is a serious pain and makes debuging much
> harder than if you can do your work on top of a working OS that can
> print debug messages.
>
> Len Sorensen
> -

But the first thing you must do in a 'roll-your-own' OS is to make
provisions to write text to (sometimes a temporary) output device
and get some input from same. Writing such basic stuff is getting
harder because many embedded systems don't have UARTS, screen-cards,
keyboards, or any useful method of doing I/O. This is where an
existing OS (Like Linux) can help you get some I/O running, perhaps
through a USB bus. You debug and make it work as a Linux
Driver, then you link the working stuff into your headless CPU
board.

Cheers,
Dick Johnson
Penguin : Linux version 2.6.13 on an i686 machine (5589.55 BogoMips).
Warning : 98.36% of all statistics are fiction.

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