[U-Boot-Users] Ideas on U-Boot configuration with FDT
Timur Tabi
timur at freescale.com
Fri May 18 16:27:13 CEST 2007
Wolfgang Grandegger wrote:
> CPU: MPC5200 v1.0, Core v1.1 at 396 MHz
> Bus 132 MHz, IPB 66 MHz, PCI 33 MHz
> FDT: FDT_ERR_BADMAGIC (or OK, or version number?)
>
> At this level also the compatibility of the FDT tree could be checked
> using fdt_boardcheck().
I think fdt_checkboard() (or boardcheck) should be run from inside the fdt_open_into()
command. This takes advantage of the existing mechanism of fdt_open_into() to return an
error. It also allows for a device tree to be opened after U-Boot has booted.
> - After relocation, the blob is copied into memory via fdt_open_into()
> to a defined place and "fdt" is updated accordingly.
So we'll need to have CFG_FDT_ADDR_FLASH and CFG_FDT_ADDR_RAM.
> Not sure, what
> location in RAM to use, but it should fit into the existing scheme.
> Any recommendations?
>
> - When U-Boot is up, "fdt" points to a valid FDT, e.g. "fdt addr" is not
> necessary.
I think this feature needs to be optional. That is, if CFG_FDT_ADDR_xxx are defined, then
we can enable this feature. Otherwise, fdt_addr will still be necessary. Remember, we'll
still need to support architectures that don't have device trees.
--
Timur Tabi
Linux Kernel Developer @ Freescale
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