From 5f4b356121fdb520e4c9bb4fe3483c1a5f93439c Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Sat, 24 Jul 2021 09:03:37 -0600 Subject: [PATCH] doc: Add a note about number representation Mention the default base of U-Boot in the command-line section. Add examples for decimal and octal. Signed-off-by: Simon Glass --- doc/usage/cmdline.rst | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/doc/usage/cmdline.rst b/doc/usage/cmdline.rst index b3dbdb8b23..2d5127c955 100644 --- a/doc/usage/cmdline.rst +++ b/doc/usage/cmdline.rst @@ -54,3 +54,34 @@ General rules 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 -- 2.39.5