0dc72120b7
Add a new 'fdt reserved' subcommand that displays all reserved memory regions defined in the device tree's /reserved-memory node. This command provides a formatted table showing the ID, name, start address, and size of each reserved memory region. Avoid a conflict with the existing 'fdt resize' command. Update the docs and add a test. Co-developed-by: Claude <noreply@anthropic.com> Signed-off-by: Simon Glass <sjg@chromium.org>
102 lines
3.0 KiB
ReStructuredText
102 lines
3.0 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
|
|
|
|
.. index::
|
|
single: fdt (command)
|
|
|
|
fdt command
|
|
===========
|
|
|
|
Synopsis
|
|
--------
|
|
|
|
::
|
|
|
|
fdt addr [-cq] [addr [len]]
|
|
fdt reserved
|
|
|
|
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.
|
|
|
|
fdt reserved
|
|
~~~~~~~~~~~~
|
|
|
|
This command prints all reserved memory regions defined in the device tree's
|
|
`/reserved-memory` node. The output shows a formatted table with the following
|
|
columns:
|
|
|
|
- **ID**: Sequential number for each region
|
|
- **Name**: Node name of the reserved memory region
|
|
- **Start**: Start address of the reserved memory region in hexadecimal
|
|
- **Size**: Size of the reserved memory region in hexadecimal
|
|
|
|
If no `/reserved-memory` node exists in the device tree, the command will
|
|
display an appropriate message. This command is useful for debugging memory
|
|
layout issues and verifying that reserved memory regions are properly defined.
|
|
|
|
This subcommand is only present is `CONFIG_CMD_FDT_RESERVED` is enabled.
|
|
|
|
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..'|
|
|
|
|
Print all reserved memory regions::
|
|
|
|
=> fdt reserved
|
|
ID Name Start Size
|
|
----------------------------------------------------------------
|
|
0 secmon@1f000000 0x000000001f000000 0x0000000001000000
|
|
1 atf@40000000 0x0000000040000000 0x0000000000200000
|
|
2 linux,cma 0x0000000050000000 0x0000000008000000
|
|
|
|
Return value
|
|
------------
|
|
|
|
The return value $? indicates whether the command succeeded.
|