looking for documentation on porting Linux to PowerPC platforms

Abraham vd Merwe abraham at 2d3d.co.za
Thu Dec 5 19:48:56 EST 2002

Hi Chris!

> > a) how to boot linux (can I just branch to the the address where I loaded t
> > he
> > image into ram or do I need to setup registers / data structures beforehand?)
> Yes, you need to setup a number of things.  Take a look at PPCBoot (now called
> U-Boot).  Porting PPCBoot is pretty straight forward.  Once you have
> PPCBoot support done for the board, you're pretty far along.

I've got a VxWorks boot loader on the thing, so I'm not worrying about a
boot loader right now. I just need to know what I need to setup before
branching to the processor. Looking at the source for the 8xx processors, it
seems I need:

------------< snip <------< snip <------< snip <------------
r3: ptr to board info data
r4: initrd_start or if no initrd then 0
r5: initrd_end - unused if r4 is 0
r6: start of command line string
r7: end of command line string
------------< snip <------< snip <------< snip <------------

Is that all? Also, what is the "board info data" ?

> > b) where/what do I change if I want to add a "sub" architecture?
> arch/ppc/platforms is what you want.  You need a LinuxPPC tree with
> what they call "platforms" support.  You can get one from the BK
> repositories.

I downloaded ppc-patch-2.4.18.bz2 from
ftp://ftp.kernel.org/pub/linux/kernel/ports/ppc - is that sufficient or is
there better support in the BK repository?

> > I've got a ICP-PPC PowerPC backplane type system here which I want to get
> > Linux on. It has the MPC8240 CPU on it which from what I read is pretty much
> > the same as the 8260, 8245, etc. (they're all based on the 603e core right?)
> >
> > Now, if I select "8xx" in menuconfig, I get another selection of machine
> > types (RPX-Lite, RPX-Classic, etc.). Obviously I need to own my own machine
> > type here, but how do I do that. Also, how does these machine types differ?
> > Just different peripherals? Do they have anything in common (e.g. uart).
> For the most part, anything based on the 8240 is going to be roughly
> similar.  You'll have to know how the chip selects are configured, and
> possibly the SDRAM controller setup, but that's usually handled by PPCBoot.
> Sometimes the kernel does additional setup in arch/ppc/platforms for
> specific targets (eg. PCI bridge config, etc.) you'll see what I mean.

Well, the boot loader have everything configured already. I'm not worried
about peripherals for now, just booting the kernel.



The first thing I do in the morning is brush my teeth and sharpen my tongue.
		-- Dorothy Parker

 Abraham vd Merwe - 2d3D, Inc.

 Device Driver Development, Outsourcing, Embedded Systems

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