Build

Run generate-images from the checkout directory.

This generates a root fs tarball (rootfs.tar.xz) and a firmware file (flash-image.bin) containing u-boot, ARM trusted firmware etc.

Install

Update the firmware image

This is necessary because the original firmware doesn't set up the PCI-E port and USB ports correctly. You'll run into all sorts of problems without the newly built firmware.

Since storage devices may or may not work with the original firmware, the safest way to update the firmware is through TFTP. Install the tftp-server package, copy flash-image.bin to /srv/tftp and run the tftp server ("systemctl start tftpd").

U-Boot uses the Ethernet port next to the USB port, so make sure that one is connected.

Then, in u-boot (the prompt you get from the board's serial console), run

env default -a
env save
setenv ethact eth2 (where eth2 is the ethernet port you want to use)
setenv serverip 1.2.3.4 (where 1.2.3.4 is your TFTP server's IP address)
setenv ipaddr 1.2.3.5 (where 1.2.3.5 is the temporary IP address your board can take)
bubt

(Watch out for failed downloads, they're usually related to the IP address not being set correctly. Set the variables bubt tells you about.)

reset

Boot the OS...

Untar rootfs.tar.xz to a SD card, USB stick or SATA harddisk (whatever you want to boot from)

Autoboot

Tell u-boot what to do -- e.g. if you've installed the OS on a SATA harddisk, with partition 1 swap, partition 2 /, partition 3 /home:

setenv bootcmd 'scsi reset; ext4load scsi 0:2 $kernel_addr /boot/Image; ext4load scsi 0:2 $fdt_addr /boot/armada-8040-mcbin.dtb; setenv bootargs $console root=/dev/sda2 rw; booti $kernel_addr - $fdt_addr'

Or if you've installed the OS on an SD card with / on partition 1:

setenv bootcmd 'ext4load mmc 1:1 $kernel_addr /boot/Image; ext4load mmc 1:1 $fdt_addr /boot/armada-8040-mcbin.dtb; setenv bootargs $console root=/dev/mmcblk1p1 rw; booti $kernel_addr - $fdt_addr'

If you ever need to return to the original autoboot setup (designed to boot over the network): setenv bootcmd 'run get_images; run set_bootargs; booti $kernel_addr $ramfs_addr $fdt_addr'