What is U-Boot command line?
U-Boot is an open source Universal Boot Loader that is frequently used in the Linux community. Xilinx provides a Git tree located at https://github.com/Xilinx/u-boot-xlnx which includes U-Boot to run on Xilinx boards. The Xilinx U-Boot project is based on the source code from http://git.denx.de.
What is U-Boot environment variables?
The U-Boot environment is a block of memory that is kept on persistent storage and copied to RAM when U-Boot starts. It is used to store environment variables which can be used to configure the system. The environment is protected by a CRC32 checksum.
How do I save environment variables in U-Boot?
If you want to save this variable and make U-Boot automaticaly fetch the kernel image and turn it on you have to save it in a bootcmd, it goes like this : Uboot > setenv bootcmd tftp 21000000 uImage\; tftp 21100000 ramdisk-rmk7\; bootm 21000000. Uboot > saveenv.
What is Setenv command?
The SETENV command can be used to define an environment variable and assign a value to it. The value of an environment variable can be retrieved from within the SAS session using the SYSGET function during autoexec processing. The command x setenv a/tmp; sets a=/tmp . The command x echo $a; results in the value /tmp.
Where is U-Boot environment stored?
SD Card memory
The U-Boot environment is stored in the SD Card memory and is persistent across power or reset cycles. Parameters defined by the U-boot environment variables include: target IP address, target MAC address, location in RAM where a Linux bootable image will be loaded, and many others.
What is the use of U-Boot in Linux?
U-Boot runs a command-line interface on a console or a serial port. Using the CLI, users can load and boot a kernel, possibly changing parameters from the default. There are also commands to read device information, read and write flash memory, download files (kernels, boot images, etc.)
Where are U-Boot environment variables stored?
How do I set environment variables in U-Boot?
U-Boot makes use of environment variables which can be read and set from the U-Boot command line with printenv and setenv. It can be helpful to read and set these variables from Linux as well. The U-Boot distribution has sources for these commands, named fw_printenv and fw_setenv .
What is this Uboot how-to?
This How-To is meant to be a starting point for people to learn how access to the uboot environment from userspace.
How does U-Boot import env data from persistent storage?
Instead, U-Boot imports all such env data stored from persistent storage into a RAM resident Hashtable. If User supplied environment is good (i.e. CRC is OK), then it is imported from flash to RAM. Otherwise, U-Boot imports the default compiled-in environment to this hashtable.
What is setenv command in Linux?
Linux setenv command 1 Syntax 2 Arguments. The name of the variable to be set. The value of the variable, as either a single word or a quoted string. 3 Description. It is used to define the value of environment variables. If setenv is given no arguments, it displays all environment variables and their values.