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- The /config node (Configuration Options)
- ----------------------------------------
- A number of run-time configuration options are provided in the /config node
- of the control device tree. You can access these using fdtdec_get_config_int(),
- fdtdec_get_config_bool() and fdtdec_get_config_string().
- These options are designed to affect the operation of U-Boot at runtime.
- Runtime-configuration items can help avoid proliferation of different builds
- with only minor changes, e.g. enabling and disabling console output. Items
- here should be those that can usefully be set by the build system after U-Boot
- is built.
- Available options are:
- bootcmd (string)
- Allows overwriting of the boot command used by U-Boot on startup. If
- present, U-Boot uses this command instead. Note that this feature can
- work even if loading the environment is disabled, e.g. for security
- reasons. See also bootsecure.
- bootdelay (int)
- This allows selecting of the U-Boot bootdelay, to control whether U-Boot
- waits on boot or for how long. This allows this option to be configured
- by the build system or by a previous-stage binary. For example, if the
- images is being packed for testing or a user holds down a button, it may
- allow a delay, but disable it for production.
- u-boot,boot-led (string)
- u-boot,error-led (string)
- This is used to specify the label for an LED to indicate an error and
- a successful boot, on supported hardware.
- bootsecure (int)
- Indicates that U-Boot should use secure_boot_cmd() to run commands,
- rather than the normal CLI. This can be used in production images, to
- restrict the amount of parsing done or the options available, to cut
- back on the available surface for security attacks.
- u-boot,efi-partition-entries-offset (int)
- If present, this provides an offset (in bytes, from the start of a
- device) that should be skipped over before the partition entries.
- This is used by the EFI/GPT partition implementation when a device
- is formatted.
- This setting will override any values configured via Kconfig.
- kernel-offset (int)
- This allows setting the 'kernaddr' environment variable, used to select
- the address to load the kernel. It is useful for systems that use U-Boot
- to flash a device, so the scripts that do this know where to put the
- kernel to be flashed.
- load-environment (int)
- Allows control over whether U-Boot loads its environment after
- relocation (0=no, 1 or not present=yes).
- u-boot,mmc-env-offset (int)
- u-boot,mmc-env-offset-redundant (int)
- If present, the values of the 'u-boot,mmc-env-offset' and/or
- of the u-boot,mmc-env-offset-redundant' properties overrides
- CONFIG_ENV_OFFSET and CONFIG_ENV_OFFSET_REDUND, respectively,
- for SD/MMC devices.
- Values are interpreted as the offset from the start of the
- device, specified in bytes. It is assumed that the setting
- will point at the beginning of a LBA and values that are not
- LBA-aligned will be rounded up to the next LBA address.
- u-boot,mmc-env-partition (int)
- if present, the environment shall be placed at the last
- CONFIG_ENV_SIZE blocks of the partition on the
- CONFIG_SYS_MMC_ENV_DEV.
- if u-boot,mmc-env-offset* is present, this setting will take
- precedence. In that case, only if the partition is not found,
- mmc-env-offset* will be tried.
- u-boot,no-apm-finalize (bool)
- For x86 devices running on coreboot, this tells U-Boot not to lock
- down the Intel Management Engine (ME) registers. This allows U-Boot to
- access the hardware more fully for platforms that need it.
- u-boot,no-keyboard (bool)
- Tells U-Boot not to expect an attached keyboard with a VGA console.
- rootdisk-offset (int)
- This allows setting the 'rootdisk' environment variable, used to select
- the address to load the rootdisk. It is useful for systems that use
- U-Boot to flash a device, so the scripts that do this know where to put
- the root disk to be flashed.
- silent-console (int)
- If present and non-zero, the console is silenced by default on boot.
- u-boot,spl-payload-offset (int)
- If present (and SPL is controlled by the device-tree), this allows
- to override the CONFIG_SYS_SPI_U_BOOT_OFFS setting using a value
- from the device-tree.
- sysreset-gpio (string)
- If present (and supported by the specific board), indicates a
- GPIO that can be set to trigger a system reset. It is assumed
- that such a system reset will effect a complete platform reset,
- being roughly equivalent to a power-on reset.
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