[Ltib] Re: dtb(device tree binary)

[Vijay Nikam]

Hello Stuart,

 

Thank you for the useful information ... you gave ... atleast now I can think in the way you described regarding dtb ...

 

Yes I agree it was not an ltib question but I asked to have some inital input ... thanks anyway ...

 

Kind Regards,

Vijay Nikam

 

On 7/25/08, Stuart Hughes <address@hidden> wrote:

Hi Vijay,

The dtb file is a binary file for powerpc that provide a data structure
describing the hardware on a board.  This is needed by the kernel when
booting.

Prior to linux-2.6.16 this kind of information was passed by the
bootloader via the bd_info (ppc targets rather than powerpc).

So yes you definitely need it.  Normally this dtb tree is somewhere in
flash or loaded into memory, and it's location is passed as an argument
to u-boot when you want to boot the kernel.

You can wrap the kernel with this dtb file using a cuImage.  This would
allow to boot with older u-boots or bootloaders that don't handle device
trees.  How you build a cuImage depends on kernel version (in the latest
they pop out if you say 'make zImage').   One caution though, cuImage
dtb files are fixed, but supposedly some boot-loaders are able to
manipulate the dtb tree directly.

This is about as much as I know about dtb.  Really this is not an ltib
thing and you'd get more informed advice from the linux-ppc (or similar)
mailing list.

Regards, Stuart

On Fri, 2008-07-25 at 12:10 +0530, Vijay Nikam wrote:
> Hello,
>
> I would like to ask ...
>
> what is the significance of dtb (device tree binary) ? ? ?
>
> Do I need to have it in the system  ? ? ? if yes then how I can
> directly merge into the kernel ? ? ? (particularly in case of loading
> kernel from NAND flash)
>
> As when I build the bootloader kernel and FS then this dtb is also
> generated ... and if I will not load it then the kernel will not load
> properly and FS is not mounted ... Currenly I am in this situation ...
>
> Kindly please acknowledge ... thank you ...
>
> Kind Regards,
> Vijay Nikam
>
>