[Lenny400] [Mipsbook-devel] Reviewing the Ingenic board initialisation code

Daniel Glöckner daniel-gl at gmx.net
Wed Jun 10 01:45:27 CEST 2015


On Tue, Jun 09, 2015 at 07:21:00PM +0200, Dr. H. Nikolaus Schaller wrote:
> > I imagine that booting a single payload with appended DT information is 
> > probably desirable in many different environments. Indeed, I thought that this 
> > was being widely done on the supported platforms already.
> 
> Well, in my experience it is easier to have a common binary uImage that
> fits all devices and just change the device tree file that is loaded by u-boot.
> 
> This avoids the step of making and publishing n different uImages for n devices.
> 
> Just n different small DTB files. And, DTB should become stable, i.e. survive
> kernel upgrades so that only the uImage needs to be swapped.
> 
> Finally, the file name of the DTB can match the device name.Since U-Boot is
> usually also device specific it is easier to distribute an U-Boot+DTB bundle
> and a separate kernel image.

U-Boot writes some values into the device tree, like the base address and
size of the RAM. This allows sharing of the device tree across boards with
slight variations. You can also do arbitrary changes to the device tree
from boot scripts with U-Boot's fdt command if the tree is a separate file.

Best regards,

  Daniel


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