Re: Organisation of 4xx initialization code

On Fri, Nov 16, 2001 at 11:46:12AM -0500, Dan Malek wrote:

David Gibson wrote:

quoted

Thoughts?

For some reason, the 4xx "structure" wasn't started correctly and
has taken a weird path.  I've discussed this with a few folks that
have asked about it.  Unfortunately, I've been working on a variety
of 4xx boards just to get them to work and haven't been able to
spend time sorting this out.

I don't have a response to your specific question, but in general
we have messed up the 4xx processor/board configuration.  This starts
all of the way from the include files and I'm sure exists in other
source files.  The problem I have with 4xx is we conceptually start with a
processor type, and then try to determine what board we have.  If you
use the 8xx as a model, it is done the other way around.  You first
start with some architecture common things, then do the board, then
let the board determine further unique processor or I/O configuration
details.  Other platforms seem to do something similar.

We need to start right at the top.  The ibm4xx.h file should include
the properly configured board description file, then that file should
include the proper processor type.  The kernel initialization should
do the same.

Specific to your question, I guess you are proposing to have a bunch
of platform_init functions, one for each board, then have them call generic
4xx functions if necessary.  Makes sense.

Who is going to restructure this and when is it going to be done :-)?
I have a big mess of STB and other 4xx stuff to check in, and it
doesn't fit anywhere right now (but is closer to the current model).

I'm offering...  As far as I can see the sanest (i.e. least gratuitous
breakage) way to do it is as follows:  create a new ppc4xx.c which
will probably have a lot of code copied out of ppc4xx_setup.c, migrate
one or two boards (probably ep405 and walnut, because I have access)
over to have their own platform_init() calling code in ppc4xx.c.
Gradually move each of the other 4xx machines over to the new scheme
and finally remove ppc4xx_setup.c

--
David Gibson			| For every complex problem there is a
david@gibson.dropbear.id.au	| solution which is simple, neat and
				| wrong.  -- H.L. Mencken
http://www.ozlabs.org/people/dgibson


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