doc/README.silent

   1 The config option CONFIG_SILENT_CONSOLE can be used to quiet messages
   2 on the console.  If the option has been enabled, the output can be
   3 silenced by setting the environment variable "silent".
   4
   5 - CONFIG_SILENT_CONSOLE_UPDATE_ON_SET
   6         When the "silent" variable is changed with env set, the change
   7         will take effect immediately.
   8
   9 - CONFIG_SILENT_CONSOLE_UPDATE_ON_RELOC
  10         Some environments are not available until relocation (e.g. NAND)
  11         so this will make the value in the flash env take effect at
  12         relocation.
  13
  14 The following actions are taken if "silent" is set at boot time:
  15
  16  - Until the console devices have been initialized, output has to be
  17    suppressed by testing for the flag "GD_FLG_SILENT" in "gd->flags".
  18
  19  - When the console devices have been initialized, "stdout" and
  20    "stderr" are set to "nulldev", so subsequent messages are
  21    suppressed automatically. Make sure to enable "nulldev" by
  22    #defining CONFIG_SYS_DEVICE_NULLDEV in your board config file.
  23
  24  - When booting a linux kernel, the "bootargs" are fixed up so that
  25    the argument "console=" will be in the command line, no matter how
  26    it was set in "bootargs" before. If you don't want the linux command
  27    line to be affected, define CONFIG_SILENT_U_BOOT_ONLY in your board
  28    config file as well, and this part of the feature will be disabled.