RE: [PATCH] powerpc/bootwrapper: Add documentation of boot wrappertargets

-----Original Message-----
From: Josh Boyer [mailto:jwboyer@gmail.com]
Sent: Thursday, June 26, 2008 12:07 PM
To: Stephen Neuendorffer
Cc: grant.likely@secretlab.ca; John Linn; linuxppc-dev@ozlabs.com;

paulus@samba.org;

petermendham@computing.dundee.ac.uk
Subject: RE: [PATCH] powerpc/bootwrapper: Add documentation of boot

wrappertargets

=

On Thu, 2008-06-26 at 09:48 -0700, Stephen Neuendorffer wrote:

quoted

My unanswered questions:

1) Why are there 4 different types of targets that embed a device

tree?

quoted

I assume they differ in how they are started loaded, but

(unfortunately)

quoted

the names are meaningless (With the exception of cuImage, which is

only

quoted

cryptic.. :)  If I'm adding support for a new board, which should I

use?

=

They are all needed to deal with different firmwares.

Where 'firmware' really means 'method of invoking the kernel'

treeImage is for OpenBIOS based boards (Ebony, Walnut, some boards
running PIBS can also use this).  This firmware requires a special
header on the image file.

So it's not an elf? or it is an .elf?  maybe it should be
'openBiosImage'?
 =

cuImage is for boards running an older U-Boot that does not understand
device trees.

Forgive my ignorance here, but what specifically does this imply?  As
far as I can tell, generally speaking, some of the board-specific
information is passed into the boot wrapper, which then stuffs it into
the device tree.

uImage is for device-tree aware U-Boot versions

And this differs from above because it gets a device tree passed in,
which uboot has already stuffed correctly.

dtbImage is used for boards that can take an ELF zImage, but still

need

a dtb provided.
=

simpleImage, not sure here.

So both of these are elfs...  but how do they differ?  Is it only in how
the right head.s file gets picked up?

Steve


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