Run from flash with U-Boot [FreeBSD WIKI]

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====== How to run from flash with U-Boot. ======
Keywords: U-Boot, embedded

1. Ask U-Boot: "what do you support to boot?"

Normally, U-Boot use special image for kernel/ramfs packing. But we
need to know which compression support U-Boot that fleshed to our
target board.

First way:
use mkimage utility (/usr/ports/devel/u-boot) and make test
images for all supported by mkimage compression types.

<code>
mkimage -A ${TARGET} -O linux -T kernel \
            -C ${COMPRESSION_TYPE} \
            -a ${RAM_START_ADDRESS} \
            -e ${RAM_START_ADDRESS} \
            -n 'FreeBSD Kernel Image' \
            -d SOME_SMALL_FILE_NAME \
            test.uboot
</code>

Then for each file, do transfer to board and run from image with
`bootm' command. And check what U-Boot answer you, if answer like
"Unimplemented compression type ?", then you know :).

Second way:
From running Linux or U-Boot get first 64k block from kernel partition
in flash.

Break your mkimage utility: avoid exit when we do "show info" (key -i)
CRC failed. And check compression type of 64k file we get from device.

Or just delete U-Boot image header from file

<code>
dd if=64k.file of=just_kern bs=64 skip=1
</code>

and check with file(1) utility

2. Create image
2.1. More canonical way, we have mkimage, gzip or bz2 and compiled
kernel, maybe kernel.bin also.

<code>
gzip --best --force vmlinux.bin
</code>

for ELF kernel:

<code>
mkimage -A mips -O linux -T kernel \
            -C gzip \
            -a ${LOAD_ADDRESS} \
            -e ${START_ADDRESS} \
            -n 'FreeBSD Kernel Image' \
            -d kernel \
            kernel.uboot
</code>

<code>
LOAD_ADDRESS - in most cases this is RAM base address
START_ADDRESS = LOAD_ADDRESS + ELF_HEADER_SIZE (0x1000 for ELF image) 
</code>

for kernel.bin:

<code>
LOAD_ADDRESS = RAM_BASE_ADDRESS + 0x1000
START_ADDRESS = RAM_BASE_ADDRESS + 0x1000 
</code>

Don't forget to check/change KERNLOADADDR of kernel config file.
KERNLOADADDR must be equal to START_ADDRESS.

2.2. Longest way, but have smallest footprint, used only if
U-Boot support LZMA.

Problem 1: Current version of mkimage from ports, don't support LZMA.
So we need new: http://my.ddteam.net/files/u-boot.new.tar.gz

Problem 2: Devices I know support only old LZMA.
I use LZMA 4.17.

Then mkimage, like in 2.2., but -C lzma.

3. Now we have kernel U-Boot image, so transfer it to device and try
with `bootm' command.

4. If all fine, write image to flash kernel partition.