doc: karo: added description of 'boot_mode' variable

diff --git a/doc/README.KARO-TX53 b/doc/README.KARO-TX53
index e4c99d3fc732b13a07e12a5e1c997dac2babb626..b20a7595a8591fc12443ea1b9e83413cf516fae9 100644 (file)
--- a/doc/README.KARO-TX53
+++ b/doc/README.KARO-TX53
@@ -49,6 +49,25 @@ U-Boot Features
 ---------------
 
 Environment variables:
+boot_mode     selects which boot script will be used by 'bootcmd' to
+             boot the application (Linux)
+             supported values:
+             nand: (default) load kernel from NAND partition 'linux'
+                             and mount rootfs (fstype UBIFS)
+                             from partition 'rootfs'. 
+             mmc:            load kernel from file 'uImage' on first
+                             partition (FAT) on (first) SD/MMC card
+                             and mount rootfs (fstype autodetected)
+                             from second partition.
+             net:            load kernel image via tftp (file uImage)
+                             and mount rootfs via NFS. This requires
+                             the additional variables 'nfsroot'
+                             (path to rootfs on NFS server) and
+                             'nfs_server' (hostname or IP address of
+                             NFS server) to be set.
+             jffs2: (legacy) load kernel from NAND partition 'linux'
+                             and mount rootfs (fstype JFFS2)
+                             from partition 'rootfs'.
 
 cpu_clk       <CPU freq [MHz]> CPU clock frequency set after boot.