mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-12-24 03:53:31 +00:00
93 lines
2.8 KiB
ReStructuredText
93 lines
2.8 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
|
|
|
|
Command-line Parsing
|
|
====================
|
|
|
|
The command line is available in U-Boot proper, enabled by CONFIG_CMDLINE which
|
|
is on by default. It is not enabled in SPL.
|
|
|
|
There are two different command-line parsers available with U-Boot:
|
|
the old "simple" one, and the much more powerful "hush" shell:
|
|
|
|
Simple command-line parser
|
|
--------------------------
|
|
|
|
This takes very little code space and offers only basic features:
|
|
|
|
- supports environment variables (through :doc:`cmd/env`)
|
|
- several commands on one line, separated by ';'
|
|
- variable substitution using "... ${name} ..." syntax
|
|
- special characters ('$', ';') can be escaped by prefixing with '\',
|
|
for example::
|
|
|
|
setenv bootcmd bootm \${address}
|
|
|
|
- You can also escape text by enclosing in single apostrophes, for example::
|
|
|
|
setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
|
|
|
|
Hush shell
|
|
----------
|
|
|
|
This is similar to Bourne shell, with control structures like:
|
|
|
|
- `if`... `then` ... `else`... `fi`
|
|
- `for`... `do` ... `done`
|
|
- `while` ... `do` ... `done`
|
|
- `until` ... `do` ... `done`
|
|
|
|
Hush supports environment ("global") variables (through setenv / saveenv
|
|
commands) and local shell variables (through standard shell syntax
|
|
`name=value`); only environment variables can be used with the "run" command
|
|
|
|
The Hush shell is enabled with `CONFIG_HUSH_PARSER`.
|
|
|
|
General rules
|
|
-------------
|
|
|
|
#. If a command line (or an environment variable executed by a "run"
|
|
command) contains several commands separated by semicolon, and
|
|
one of these commands fails, then the remaining commands will be
|
|
executed anyway.
|
|
|
|
#. If you execute several variables with one call to run (i. e.
|
|
calling run with a list of variables as arguments), any failing
|
|
command will cause "run" to terminate, i. e. the remaining
|
|
variables are not executed.
|
|
|
|
Representing numbers
|
|
--------------------
|
|
|
|
Most U-Boot commands use hexadecimal (hex) as the default base, for convenient
|
|
use of addresses, for example::
|
|
|
|
=> md 1000 6
|
|
00001000: 2c786f62 00697073 03000000 0c000000 box,spi.........
|
|
00001010: 67020000 00000000 ...g....
|
|
|
|
There is no need to add a `0x` prefix to the arguments and the output is shown
|
|
in hex also, without any prefixes. This helps to avoid clutter.
|
|
|
|
Some commands use decimal where it is more natural::
|
|
|
|
=> i2c dev 0
|
|
Setting bus to 0
|
|
=> i2c speed
|
|
Current bus speed=400000
|
|
=> i2c speed 100000
|
|
Setting bus speed to 100000 Hz
|
|
|
|
In some cases the default is decimal but it is possible to use octal if that is
|
|
useful::
|
|
|
|
pmic dev pmic@41
|
|
dev: 1 @ pmic@41
|
|
=> pmic write 2 0177
|
|
=> pmic read 2
|
|
0x02: 0x00007f
|
|
|
|
It is possible to use a `0x` prefix to use a hex value if that is more
|
|
convenient::
|
|
|
|
=> i2c speed 0x30000
|
|
Setting bus speed to 196608 Hz
|