DULG

The following command builds the U-Boot images:

bash$ make all

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.