ABLE has a flexible system to automatically run a given user
command at boot time. The command to be run is controlled by the
boot.cmd
non volatile
variable. If the boot command is not set it defaults to the
autoboot command.
The execution of the boot process may be prevented by setting
the boot.auto
variable
to true. If the boot.auto
variable is not set or set
to false the boot command is run after a delay set by the
boot.timeout
variable. The delay
is in seconds and allows the user to abort the boot process by
pressing a key. The console input from which the keypress is
accepted is described in detail in Chapter 5, ABLE Console.
The boot command is executed by the ABLE shell. Any shell
script command may be placed in the boot.cmd
seperated by
semicolons. If more than a small number of commands need to be
issued they should be placed in a shell script and the script
executed.
Example 7.1. Displaying a logo during the automatic boot process
This example shows how the boot.cmd
can be set to display a
logo on the video console before continuing with an automated
boot using the autoboot command.
>nvset boot.cmd "display -d s3c2410x-video (tftpboot)logo.bmp.Z ; autoboot" >nvshow boot.cmd boot.cmd = display -d s3c2410x-video (tftpboot)logo.bmp.Z ; autoboot >nvset boot.auto true >nvshow boot.auto boot.auto = on >nvset boot.timeout 1 >nvshow boot.timeout boot.timeout = 1 >nvset console.level 5 >nvsave >reset No Available Targets >
Some of the examples presented in Section 5.5, “Practical use of the console system” make user of the automatic boot process and may be of interest.
Figure 7.1, “Initial boot operations” shows the
logic of the initial start process. The operation is to loop for
keyboard input for the time specified in boot.timeout
. If no user input is
received before the timeout the boot.cmd
variable is inspected, if
set the command is executed with the ABLE shell otherwise the
autoboot command is
executed by default.