Re: [Ltib] Upgrading Linux Kernel on EP885 Board

[Stuart Hughes]

Hi Sagar,

Here's my simplified understanding.  Before 2.6.16 the assumption was 
that the boot information would be passed in a bd_info structure by the 
bootloader.  With the flat device tree instead u-boot passes the 
location in memory containing the flat device tree.  The kernel uses 
this to figure out the hardware configuration when booting.  U-boot 
changed by allowing an extra parameter to pass the dtb location.

Note that theoretically you can build an image that has the dtb attached 
to the kernel (it was called cuImage but I think has changed).  For more 
details you'll need to ask on a PowerPC kernel mailing list.

Regards, Stuart

sagar kadam wrote:
> Hi Stuart,
>         Thanks for your help.Regarding your reply I have some queries as 
> follows, please can you take a look at these:-
>
>     1/ the board level dependencies are whether or not that platform is
>     actively supported in the mainline kernel.  Your best bet to find
>     out is to ask your vendor.  The other thing to bear in mind is your
>     bootloader.  After 2.6.16 PowerPC changed to using flat device trees
>     and so the boot semantics are different (as on the kernel/u-boot
>     list for more information).
>
>
>  >>If 2.6.16 onwards has flat device tree, then what is there in the 
> versions before this.What is the significance of this flat device 
> tree.Also there must have also been corresponding changes in the U-boot 
> as well so as to support the flat device tree. If yes then from what 
> version onwards it has been implemented?
>
> Thanks. 
>
>
>
> --
> BR,
> Sagar Kadam
>
>
>
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