[U-Boot] bootm command: is there any load address limitation for fdt?

[Wolfgang Denk]

Dear Richard Retanubun,

In message <49404A1C.1070801 at RuggedCom.com> you wrote:
> 
> I am trying to limit the amount of memory needed to load and boot a linux kernel (2.6.26)
> to do this I loaded my fdt at address 0x20_0000 and uImage at 0x_30_0000
> 
> When I run bootm, I both the kernel and fdt passed their checksum tests, and then I got this error.
> ERROR: image is not a fdt - must RESET the board to recover.

...so the uncompressed Linux kernel image was written on top of your
FDT image, corrupting it.

> However, if I loaded my fdt at address 0x40_0000 and uImage at 0x50_0000, bootm works fine.

Makes sense.

> Is there a reason why fdt must be loaded at a specific offset from the start of RAM?

Yes, there is - you need free space to load  the  uncompressed  Linux
kernel to low memory.

Best regards,

Wolfgang Denk

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