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

[Paul Boddie]

On Tuesday 9. June 2015 17.26.07 Dr. H. Nikolaus Schaller wrote:
> 
> I have to correct myself.
> 
> Yesterday, JZ4740 DT support has found its way into linux-next:
> 
> 	https://git.kernel.org/cgit/linux/kernel/git/next/linux-
next.git/commit/?id=e6382f138edd218dbe7757cf12f0b64e2926400f
> 
> So we definitvely will see it as part of the 4.2-rc series :)

Yes, it looks like the beginning of full device tree support, at least.

> A minor problem will be how to boot a DT kernel… We can’t easily modify
> U-Boot to load the .dtb and pass its address to the bootm command.
> 
> But it is usually possible to append the DTB before using mkimage to build
> an uImage. Then, the kernel startup code will scan the kernel binary for a
> DTB.
> 
> I hope this mechanism exists for MIPS as well and not only for ARM. It
> needs some CONFIG to be enabled.
> 
> We also use this method for the GTA04 if we boot from NAND. There we also
> can’t load a separate DTB (because we have no dedicated partition for it).
> 
> Here is the code that merges an existing uImage and some DTB into a
> bootable thing:
> 
> 	http://git.goldelico.com/?p=gta04-rootfs.git;a=blob;f=config/root/flash-
nand;hb=HEAD#l152

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.

Paul