xref: /openbmc/u-boot/doc/README.silent (revision c6af2e7d)
1The config option CONFIG_SILENT_CONSOLE can be used to quiet messages
2on the console.  If the option has been enabled, the output can be
3silenced by setting the environment variable "silent".  The variable
4is latched into the global data at an early stage in the boot process
5so deleting it with "setenv" will not take effect until the system is
6restarted.
7
8The following actions are taken if "silent" is set at boot time:
9
10 - Until the console devices have been initialized, output has to be
11   suppressed by testing for the flag "GD_FLG_SILENT" in "gd->flags".
12
13 - When the console devices have been initialized, "stdout" and
14   "stderr" are set to "nulldev", so subsequent messages are
15   suppressed automatically. Make sure to enable "nulldev" by
16   #defining CONFIG_SYS_DEVICE_NULLDEV in your board config file.
17
18 - When booting a linux kernel, the "bootargs" are fixed up so that
19   the argument "console=" will be in the command line, no matter how
20   it was set in "bootargs" before.
21