Porting the 2.6.38 linux kernel to ARM11 MPcore

[arnd@arndb.de (Arnd Bergmann)]

On Friday 18 November 2011, Moln?r G?bor wrote:
> im working on a project wich aims at porting the 2.6.38 kernel to an
> arm11 mpcore based board.
> 
> ...
>
> Im only a beginner, and im sorry for the low quality of the question,
> i appreciate any help. Even comments on how 'accomplishable' this
> project is. Also, the board is not a realview board, but it might not
> be an issue at this stage.

Hi Moln?r,

I hope I'm not discouraging you too much, but from a high-level perspective
this sounds like a rather pointless goal, mostly because 2.6.38 is
rather old now and doing a port for that version would end up looking
very different from how we are doing things for new kernel releases.

Now if you were thinking about doing a port for mainline Linux (currently
that means targetting developing on 3.2-rc and targetting 3.3 or 3.4),
things would look much brighter.

The most important question is what hardware "platform" this port is for,
not so much the CPU core. The only two platform we support in Linux with
an ARM11 MPCore are cns3xxx and realview. You already mentioned that you
don't target realview. If your board is instead based on a Cavium Networks
SOC, things should be fairly easy and you only need to add a new machine
description in arch/arm/mach-cns3xxx. If you are working with an SOC
from a different family that is already supported by Linux, you have
to add support for the specific SOC, and the work involved in that 
depends a lot on the particular SOC.

For any other SOC that has no support whatsoever in Linux, I would suggest
getting the latest Linux kernel from git (3.2-rc2) and looking at the
highbank, prima2, picoxcell and zynq platforms in there. The code you
need to write should look similar to any of these, rather than the realview
platform, which is a fairly unusual one. In case of a new SOC platform,
you should be prepared to also write device drivers for any vendor
specific component that you want to support, e.g. network, mmc, audio,
so I would recommend first researching how many of the components on
the board already have drivers in Linux.

	Arnd