-partition name used commonly with fastboot. Current implentation checks
-aliases when accessing partitions by name (flash_write and erase functions).
-To define a partition alias add an environment variable similar to:
-fastboot_partition_alias_<alias partition name>=<actual partition name>
-Example: fastboot_partition_alias_boot=LNX
+partition name used commonly with fastboot.
+
+The current implementation checks aliases when accessing partitions by
+name (flash_write and erase functions). To define a partition alias
+add an environment variable similar to:
+
+``fastboot_partition_alias_<alias partition name>=<actual partition name>``
+
+for example:
+
+``fastboot_partition_alias_boot=LNX``
+
+Variable overrides
+------------------
+
+Variables retrived through ``getvar`` can be overridden by defining
+environment variables of the form ``fastboot.<variable>``. These are
+looked up first so can be used to override values which would
+otherwise be returned. Using this mechanism you can also return types
+for NAND filesystems, as the fully parameterised variable is looked
+up, e.g.
+
+``fastboot.partition-type:boot=jffs2``
+
+Boot command
+------------
+
+When executing the fastboot ``boot`` command, if ``fastboot_bootcmd`` is set then
+that will be executed in place of ``bootm <CONFIG_FASTBOOT_BUF_ADDR>``.