[U-Boot-Users] DTB /OF_TREE Newbie and U-boot

Timur Tabi timur at freescale.com
Thu Jan 18 20:07:16 CET 2007

Russell McGuire wrote:

> I realize now that for SOC chips such as a MPC8360E that passing a DTB 
> structure into the bootm command is probably a required step??? Is this 
> True?


> If so I see in some cases that this structure might be partly 
> constructed within the U-boot code, at least I see code doing something 
> with OF_TREE’s.

Yes, U-Boot updates the tree with its own values.

> 1)       Is the U-boot compilation process generating a .dtb structure 
> that we can burn into firmware, at least or certain CPU architectures?

No.  You need to use the DTC compiler, which is available here: 

> 2)       Is this a manual process that requires an outside dtb compiler, 


> and if so why is U-boot code dealing with this?

Because the Linux kernel is currently coded such that the boot loader must pass 
the DTB to it.  To reduce the amount of dual-maintenance, U-Boot can take some 
of the data that it knows about, and put that into the tree.

> 3)       Is this built into the bd_info structure?

I'm not sure I understand.  The DTB itself is not part of U-Boot, but U-Boot can 
parse the tree and modify it.

Timur Tabi
Linux Kernel Developer @ Freescale

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