README-uboot-env

This program is used to read or modify U-Boot environment variables in
an image file or on a block boot device (e.g. SD card or USB drive that
contains U-Boot).

The configuration file (/etc/uboot-env.conf) contains valid device
names with offsets and lengths.  The default configuration may need to
be changed for your specific device.

The config file distributed is one that works with the CuBox-i, with
an offset of 0x60000 for 0x2000.

If you specify an image file (one that's intended to be written directly
to the block device used to boot a system) you'll need to specify the
offset.  Although the configuration file could be modified to have a
non-zero default for the offset, it probably isn't a good idea.

The environment save area is protected by a CRC32 checksum.  For safety,
uboot-env will immediately exit if the checksum is not correct, unless
the -I flag is used (in which case the checksum must NOT be correct, it
can only be used to initialize an area known to be invalid).


Usage: uboot-env [-cdfol] get -s filename
       uboot-env [-cdfol] get [var1 ... ]
       uboot-env [-cdfol] del [var1 ... ]
       uboot-env [-cdfol] del -[i|I]
       uboot-env [-cdfol] set -s filename
       uboot-env [-cdfol] set var val
       uboot-env [-cdfol] set < uEnv.txt

      -c config        Alternate config file
      -d devicename    Device with environment
      -f filename      File with environment
      -s filename      Save to or set from file
      -o offset        Offset into device
      -l length        Length in device
      -i               Initialize environment
      -I               Forced initialize

When using the -s option with get, the referenced file will be overwritten
and the entire environment area will be saved (including checksum).
When used with set, the file must be long enough and the checksum must
be valid; the entire environment area on the target will be replaced.
Note that any offset applies only to the target, the save file always
has an offset of zero.

When setting a variable on the command line, you must provide one
variable name and one value argument; if there are embedded spaces or
other special characters in the value, you'll need to quote or escape it.
A variable name may not contain "=".

Setting a variable to an empty value will delete the variable.

When using the set option with no further arguments, variables and
values are read from stdin, with an "=" separating the two.  Again,
setting an empty value will delete the variable.

It is not an error to delete a non-existent variable.

When getting variables, more than one variable name may be specified.
The variables will be displayed in alphabetic order.  If no variables
are specified, all variables are retrieved.