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<TITLE>RE: [PATCH] powerpc/bootwrapper: Add documentation of boot wrappertargets</TITLE>
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<P><FONT SIZE=2>simpleImage should also create an .elf (for xmd or systemAce loading)<BR>
If dtbImage and simpleImage could be merged, I'd be all for it...<BR>
<BR>
At some point of course, I need to figure merge the Device Tree in BRAM code that I've been using, which would be a simpleImage which wouldn't need a device tree. However, I don't see this happening before August.<BR>
<BR>
Steve<BR>
<BR>
-----Original Message-----<BR>
From: glikely@secretlab.ca on behalf of Grant Likely<BR>
Sent: Fri 6/27/2008 9:22 PM<BR>
To: Stephen Neuendorffer<BR>
Cc: Josh Boyer; John Linn; linuxppc-dev@ozlabs.com; paulus@samba.org; petermendham@computing.dundee.ac.uk; Scott Wood; Geoff Levand<BR>
Subject: Re: [PATCH] powerpc/bootwrapper: Add documentation of boot wrappertargets<BR>
<BR>
On Thu, Jun 26, 2008 at 1:16 PM, Stephen Neuendorffer<BR>
<stephen.neuendorffer@xilinx.com> wrote:<BR>
> Forgive my ignorance here, but what specifically does this imply? As<BR>
> far as I can tell, generally speaking, some of the board-specific<BR>
> information is passed into the boot wrapper, which then stuffs it into<BR>
> the device tree.<BR>
<BR>
Yes, you are correct. I'll fill out the documentation more here.<BR>
<BR>
>> uImage is for device-tree aware U-Boot versions<BR>
><BR>
> And this differs from above because it gets a device tree passed in,<BR>
> which uboot has already stuffed correctly.<BR>
<BR>
Correct.<BR>
<BR>
>> dtbImage is used for boards that can take an ELF zImage, but still<BR>
> need<BR>
>> a dtb provided.<BR>
>><BR>
>> simpleImage, not sure here.<BR>
><BR>
> So both of these are elfs... but how do they differ? Is it only in how<BR>
> the right head.s file gets picked up?<BR>
<BR>
simpleImage is not an elf. Its a raw position-independent binary<BR>
which can be loaded anywhere in RAM.<BR>
<BR>
Some dtbImages are elfs; but there are a flat binaries. The main<BR>
difference is that all simpleImages assume that firmware provides<BR>
nothing interesting; but the flat dtbImages have custom code for<BR>
extracting a little bit of data out of the boards firmware.<BR>
<BR>
It's all a bit of a confusing mess. It might be a good idea to rework<BR>
all the image names to stuff not so non-obvious, but I'm not sure the<BR>
best way to go about it. There is a lot of historical stuff in there<BR>
where the various 'zImage.*' targets grew and morphed over time in<BR>
ways that are hard to follow. It may make more sense to change the<BR>
flat-binary dtbImages to be simpleImages instead with overrides for<BR>
specific boards (just like is done for virtex405-*). ps3 is the other<BR>
major user of dtbImage. I created the whole dtbImage stuff in the<BR>
first place to eliminate overloaded makefile targets where some<BR>
zImage% target were providing a device tree and other zImage% targets<BR>
were not. Splitting dtb-provided from dtb-not-provided targets<BR>
clarified the Makefile quite a bit. dtbImage is not a fantastic name,<BR>
but I needed something different from zImage for images with an<BR>
embedded device tree.<BR>
<BR>
Looking at the Makefile, dtbImage and simpleImage targets are<BR>
virtually identical. Perhaps it would be best to merge the targets<BR>
and deal with all the differences in the wrapper script (with the<BR>
default to just use simpleboot.S as the init code). Thoughts?<BR>
<BR>
Cheers,<BR>
g.<BR>
<BR>
--<BR>
Grant Likely, B.Sc., P.Eng.<BR>
Secret Lab Technologies Ltd.<BR>
<BR>
<BR>
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