Chapter 4. Setting Options

ABLE has the ability to store settings in non volatile memory. Currently all supported boards have this feature.

The commands for manipulating the non volatile memory are:


These commands are used to manipulate a set of variables which remain after reset or power cycle and are hence referred to as non-volatile. The variables are numbers, strings or boolean values. The nvshow command can be used without arguments in order to list the current values of all variables.

Example 4.1. Using the nvshow command to list the default variables

shell.hist (is unset)
boot.fs (is unset)  = off
boot.cmd (is unset)
boot.timeout (is unset)
ide.multi-limit (is unset)
usb.hubdepth (is unset)
usb.enable (is unset)
console.level  = 9
console.write (is unset) (is unset)
fb.enable (is unset)
fb.output (is unset)
fb.refresh (is unset)
fb.y (is unset)
fb.x (is unset)
sys.autoshadow (is unset)
sys.speed (is unset)

The variables, their meanings and default values are shown in Part III, “Non-Volatile Variables Reference”.

The nvset command is used to change the values of the variables its syntax is

nvset {variable} {value}

Where the variable is one of those shown in Part III, “Non-Volatile Variables Reference” and the value is correct for the variables type.

Example 4.2. Using the nvset command

This example shows the setting of three variables, one of each type, and their effects on the variables as shown by nvshow. It should be noted that to set string values with spaces in them the values must be quoted appropriately.

boot-cmd =
boot-time =
shell-hist = 0
auto-boot = off
auto-shadow = off
cons-write =
cons-read =
>nvset boot-cmd "boot (hd0)/vmlinuz root=/dev/hda1"
>nvset boot-time 1
>nvset auto-boot on
boot-cmd = boot (hd0)/vmlinuz root=/dev/hda1
boot-time = 1
shell-hist = 0
auto-boot = on
auto-shadow = off
cons-write =
cons-read =

Values altered with the nvset command are not permanent until the nvsave command has been issued. The nvsave command commits the current changes to the non volatile storage, without this the changes will be lost upon a system reset.

The nvclear command can be used to restore the values back to the defaults. The nvsave should not be used to attempt to save these values, this would result in the current settings state being saved not the default values.