u-boot/doc/usage/cmd/bootdev.rst
Simon Glass e7b2ce191e bootstd: doc: Add documentation
Add documentation for this feature, including the commands and full
devicetree bindings.

Signed-off-by: Simon Glass <sjg@chromium.org>
2022-04-25 10:00:04 -04:00

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.. SPDX-License-Identifier: GPL-2.0+:
bootdev command
===============
Synopis
-------
::
bootdev list [-p] - list all available bootdevs (-p to probe)\n"
bootdev select <bm> - select a bootdev by name\n"
bootdev info [-p] - show information about a bootdev";
Description
-----------
The `bootdev` command is used to manage bootdevs. It can list available
bootdevs, select one and obtain information about it.
See :doc:`../../develop/bootstd` for more information about bootdevs in general.
bootdev list
~~~~~~~~~~~~
This lists available bootdevs
Scanning with `-p` causes the bootdevs to be probed. This happens automatically
when they are used.
The list looks something like this:
=== ====== ====== ======== =========================
Seq Probed Status Uclass Name
=== ====== ====== ======== =========================
0 [ + ] OK mmc mmc@7e202000.bootdev
1 [ ] OK mmc sdhci@7e300000.bootdev
2 [ ] OK ethernet smsc95xx_eth.bootdev
=== ====== ====== ======== =========================
The fields are as follows:
Seq:
Sequence number in the scan, used to reference the bootflow later
Probed:
Shows a plus (+) if the device is probed, empty if not.
Status:
Shows the status of the device. Typically this is `OK` meaning that there is
no error. If you use -p and an error occurs when probing, then this shows
the error number. You can look up Linux error codes to find the meaning of
the number.
Uclass:
Name of the media device's Uclass. This indicates the type of the parent
device (e.g. MMC, Ethernet).
Name:
Name of the bootdev. This is generated from the media device appended
with `.bootdev`
bootdev select
~~~~~~~~~~~~~~~~~
Use this to select a particular bootdev. You can select it by the sequence
number or name, as shown in `bootdev list`.
Once a bootdev is selected, you can use `bootdev info` to look at it or
`bootflow scan` to scan it.
If no bootdev name or number is provided, then any existing bootdev is
unselected.
bootdev info
~~~~~~~~~~~~~~~
This shows information on the current bootdev, with the format looking like
this:
========= =======================
Name mmc@7e202000.bootdev
Sequence 0
Status Probed
Uclass mmc
Bootflows 1 (1 valid)
========= =======================
Most of the information is the same as `bootdev list` above. The new fields
are:
Device
Name of the bootdev
Status
Shows `Probed` if the device is probed, `OK` if not. If `-p` is used and the
device fails to probe, an error code is shown.
Bootflows
Indicates the number of bootflows attached to the bootdev. This is 0
unless you have used 'bootflow scan' on the bootflow, or on all bootflows.
Example
-------
This example shows listing available bootdev and getting information about
one of them::
U-Boot> bootdev list
Seq Probed Status Uclass Name
--- ------ ------ -------- ------------------
0 [ + ] OK mmc mmc@7e202000.bootdev
1 [ ] OK mmc sdhci@7e300000.bootdev
2 [ ] OK ethernet smsc95xx_eth.bootdev
--- ------ ------ -------- ------------------
(3 devices)
U-Boot> bootdev sel 0
U-Boot> bootflow scan
U-Boot> bootdev info
Name: mmc@7e202000.bootdev
Sequence: 0
Status: Probed
Uclass: mmc
Bootflows: 1 (1 valid)
Return value
------------
The return value $? is always 0 (true).