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- .. SPDX-License-Identifier: GPL-2.0+
- fdt command
- ===========
- Synopis
- -------
- ::
- fdt addr [-cq] [addr [len]]
- Description
- -----------
- The fdt command provides access to flat device tree blobs in memory. It has
- many subcommands, some of which are not documented here.
- Flags:
- -c
- Select the control FDT (otherwise the working FDT is used).
- -q
- Don't display errors
- The control FDT is the one used by U-Boot itself to control various features,
- including driver model. This should only be changed if you really know what you
- are doing, since once U-Boot starts it maintains pointers into the FDT from the
- various driver model data structures.
- The working FDT is the one passed to the Operating System when booting. This
- can be freely modified, so far as U-Boot is concerned, since it does not affect
- U-Boot's operation.
- fdt addr
- ~~~~~~~~
- With no arguments, this shows the address of the current working or control
- FDT.
- If the `addr` argument is provided, then this sets the address of the working or
- control FDT to the provided address.
- If the `len` argument is provided, then the device tree is expanded to that
- size. This can be used to make space for more nodes and properties. It is
- assumed that there is enough space in memory for this expansion.
- Example
- -------
- Get the control address and copy that FDT to free memory::
- => fdt addr -c
- Control fdt: 0aff9fd0
- => cp.b 0aff9fd0 10000 10000
- => md 10000 4
- 00010000: edfe0dd0 5b3d0000 78000000 7c270000 ......=[...x..'|
- The second word shows the size of the FDT. Now set the working FDT to that
- address and expand it to 0xf000 in size::
- => fdt addr 10000 f000
- Working FDT set to 10000
- => md 10000 4
- 00010000: edfe0dd0 00f00000 78000000 7c270000 ...........x..'|
- Return value
- ------------
- The return value $? indicates whether the command succeeded.
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