board/avnet/zedboard/: improve readme.txt explanations

Zedboard information including schematics, reference designs, and manuals are

available from http://www.zedboard.org .

To boot the Zedboard using a buildroot generated image copy the following files

to the sdcard:

	zynq-zed.dtb -> devicetree.dtb

	rootfs.cpio.gz.uboot -> uramdisk.image.gz

	uImage -> uImage

	boot.bin -> boot.bin

The U-Boot firmware for the Xilinx Zynq All Programmable SoC depends

on some propietary code. This dependency consists of a pair of

files are available from the Xilinx SDK installation.

U-Boot SPL Support

-------------

You will need these files from Xilinx SDK installation to generate

the U-Boot firmware:

	ps7_init.c

	ps7_init.h

Buildroot will create the following files and place them in the

<output>/images directory.

	zynq-zed.dtb

	rootfs.cpio.uboot

	uImage

	u-boot.img

	boot.bin

uboot.bin  -- U-Boot SPL w/ Xilinx boot.bin wrapper

---------------------------------------------------

Due to licensing issues, the files ps7_init.c/h are not able to be

distributed with the U-Boot source code.  These files are required to make a

boot.bin file.

If you already have the Xilinx tools installed, the follwing sequence will

If you already have the Xilinx tools installed, the following sequence will

unpack, patch and build the rfs, kernel, uboot, and uboot-spl.

make zedboard_defconfig

make uboot-patch

cp ${XILINX}/ISE_DS/EDK/sw/lib/hwplatform_templates/zed_hw_platform/ps7_init.{c,h} \

output/build/uboot-xilinx-v2014.1/boards/xilinx/zynq/

output/build/uboot-xilinx-v2014.1/board/xilinx/zynq/

After copying these files into the U-Boot source tree, you can

continue the build with:

make

*Notice*

While the build will successfully complete without the ps7_init.*

files,  the uboot.bin file generated by this configuration will not

function properly on the Zedboard.  Therefore, it is imperative that

the ps7_init.* files be copied into the U-Boot source tree any time

the clean, or uboot-dirclean targets are made.

Resulting system

----------------

A FAT32 partition should be created at the beggining of the SD Card

and the following files should be installed:

	/boot.bin

	/devicetree.dtb

	/uImage

	/uramdisk.image.gz

	/u-boot.img

All needed files can be taken from output/images/

boot.bin, uImage and u-boot.img are direct copies of the same files

available on output/images/

devicetree.dtb is just zynq-zed.dtb renamed.

uramdisk.image.gz is rootfs.cpio.uboot renamed