On Thu, 19 Jan 2012, Grant Likely wrote:

On Thu, Jan 19, 2012 at 10:50 AM, Russell King - ARM Linux
[off-list ref] wrote:

quoted

On Thu, Jan 19, 2012 at 05:27:15PM +0000, Pawel Moll wrote:

quoted

On Thu, 2012-01-19 at 17:00 +0000, David Vrabel wrote:

quoted

The problem wasn't with including skeleton.dtsi.

Including as it is creates two device_type="memory" nodes, one with
regs=<0 0>, which is definitely wrong.

quoted

With
CONFIG_ARM_ATAG_DTB_COMPAT the zImage decompressor modifies the appended
DTB using information from the ATAGs (see atags_to_fdt()).

If there's an ATAG giving the amount of RAM the DTB's "memory" node is
replaced with a new one.  Since the vexpress DTBs don't have a "memory"
node it's added and the DTB ends up with two nodes describing memory.

The "memory@address" node name is in my opinion perfectly legal - p. 3.4
of the DT spec says "The name component of the node name (see 2.2.1)
shall be memory.". So the decompressor code may be wrong in looking for
adress-less "memory" node...

I don't think you can expect such early code to properly parse a DT tree
with a variability in how memory stuff is declared into that DT tree.

What if you have two memory nodes specified in the DT file, and the
ATAG data contains one?

Yes, just because it is technically legal doesn't make it okay.  The
pragmatic approach here is that the skeleton.dtsi file calls the node
"memory", so this .dts file must do the same.

quoted

The more I look at this, the more I'm convinced that Grant's idea that
DT should entirely override ATAGs all the way to the kernel proper was
the wrong solution - at least in the kernel, if we had both available,
we could make a choice there, and have the full DT library to be able
to manipulate the DT blob.

Hey!  I was originally lobbying for the dt pointer carried by an ATAG.
 Nico conviced me otherwise.  :-)

Hey!  I was originally lobbying for people to have a fully DT aware 
bootloader if they wanted to play with DT, otherwise there is no 
incentive for updated bootloaders.  But someone else convinced me 
otherwise.  :-)

Mixed bags always have loose ends.


Nicolas