UBootBuilding < DULG

%SECTION0{name=UBootBuild}% Building

The following command builds the U-Boot images:

<verbatim>
bash$ make all
</verbatim>

The result of this command is the U-Boot image in several binary
file formats:


   * _u-boot_: is in =ELF= format which is used and understood by many
        debuggers and other tools.

   * _u-boot.bin_: is a raw binary image which is also acceptable by
        many tools.  It is especially useful to install a new version
        of U-Boot when U-Boot and/or Linux are already running on your
        target.

   * _u-boot.srec_: is the same image in Motorola =[[S-Record]]= format
        which is especially useful for download over a serial port,
        for instance using the =cu= command.

U-Boot uses a special format for images like Linux kernel or
ramdisks. This serves the following purposes:

   * The images are protected by a CRC32 checksum, so that it is
     easy to detect corrupted files.

   * There is no need for a special bootstrap loader within the Linux
     kernel, since all necessary functions are provided by U-Boot
     directly. This makes it much easier to port Linux to new hardware
     and saves about 10...15% of the Linux kernel image memory
     footprint.

   * Instead of defining a default configuration for your target
     (things like console baudrate, boot arguments, network
     configuration) at Linux kernel compile time, such parameters are
     now passed by U-Boot, so that the same Linux kernel image can be
     used on many targets which need different default configurations.

   * When using a ramdisk image, it is no longer necessary to link
     Linux kernel and ramdisk into one image. Instead you can now use
     the same Linux kernel with several ramdisk images, or with root
     filesystem over NFS or on a harddisk partition; or you can keep
     one version of your ramdisk image (which is known to work) and
     use this with different versions of the Linux kernel. Especially
     when you have to deal with field upgradable systems this allows
     for more powerful and reliable upgrade concepts.

When running the =make all= command this also builds
the =mkimage= tool (in _tools/mkimage_) which is needed to create
the image format used by U-Boot.

It is recommended that you copy this file into one of the directories
in your =PATH=, for instance into the directory with
all the other cross development tools:
_/opt/eldk/usr/bin_.