The dboot
command simplifies operating system bootup by performing the following operations:
-
Downloads the required files (kernel, flattened device tree, init ramdisk) from the specified media to RAM
-
Sets the
bootargs
variable with the boot command line required for the selected operating system -
Boots the system
Syntax
=> help dboot
dboot - Digi modules boot command
Usage:
dboot <os> [source] [extra-args...]
Description: Boots <os> via <source>
Arguments:
- os: one of the operating systems reserved names:
linux|android
- [source]: tftp|nfs|nand|mmc
- [extra-args]: extra arguments depending on 'source'
source=tftp|nfs -> [filename]
- filename: kernel file to transfer (if not provided, filename
will be taken from the variable pointed to by
$dboot_kernel_var)
source=nand -> [partition] [filename]
- partition: partition name (if not provided, a partition
with the name of the OS will be assumed)
- filename: kernel file to transfer (if not provided, filename
will be taken from the variable pointed to by
$dboot_kernel_var)
source=mmc|usb -> [device:part] [filename]
- device:part: number of device and partition
- filename: kernel file to transfer (if not provided, filename
will be taken from the variable pointed to by
$dboot_kernel_var)
Examples
Example 1: Boot Linux from TFTP using kernel image myImage-test
.
=> dboot linux tftp myImage-test
Example 2: Boot Linux from the internal NAND (kernel image name is taken by default from variable $zimage
):
=> dboot linux nand
Customize 'dboot' using environment variables
The behavior of the dboot
command is highly customizable through its parameters and also using the following environment variables:
Addresses
Variable | Description |
---|---|
|
RAM address where the kernel image is downloaded |
|
RAM address where the Flattened Device Tree image is downloaded |
|
RAM address where the init ramdisk image is downloaded |
Image file names
Variable | Description |
---|---|
|
Kernel image filename |
|
Flattened Device Tree image filename |
|
Init ramdisk image filename |
Modifiers
Variable | Description |
---|---|
|
Whether the kernel requires a Flattened Device Tree (FDT). Valid values are:
|
|
Whether the kernel requires an init ramdisk. Valid values are:
|
Source media
Variable | Description |
---|---|
|
Default MMC device index to read files from (when no device index is passed as parameter). |
|
Default MMC partition index to read files from (when no partition index is passed as parameter). |
Boot arguments
Variable | Description |
---|---|
|
Script that sets the |
|
Script that sets the |
|
Scripts that set the |
|
Scripts that set the |
|
NFS root path to use in the |
|
Root path to use in the |
|
Index number of the MTD partition to use as root file system when booting from NAND. |
|
Special variable that is appended to the
Locally set variables are not saved across reboots so this will pass boot arguments to the operating system only once. |
|
Placeholder for appending any customized boot arguments at the end of the kernel command line. |