tar -xjf /cdrom/U-Boot/u-boot-src.tar.bz2
Alternatively you can access the current source via the git repository:
-git://git.kernelconcepts.de/karo-tx-uboot.git master
+git://git.karo-electronics.de/karo-tx-uboot.git master
Compiling U-Boot
---------------
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.