Espressobin - building U-Boot

Continuing in the topic of the previous post - building the Kernel - I look into how Armbian builds U-Boot for the Espressobin.
There is some info on building U-Boot on the wiki but even though I tried to follow it to the letter, the U-Boot I build would never boot. Yet the U-Boot binaries build by Armbian work OK. Also note that there are several board revisions, so you certainly need sufficient new U-Boot or you can run into funny issues.

So, untangling the Armbian build scripts further (see the previous post for some context), let's see how the U-Boot is built:

the relevant sources are fetched in lib/main.sh and they are, at time of this this writing:

marvel-tools: https://github.com/MarvellEmbeddedProcessors/A3700-utils-marvell, branch A3700_utils-armada-18.12
marvell-ddr: https://github.com/MarvellEmbeddedProcessors/mv-ddr-marvell.git, branch mv_ddr-armada-18.12
ATF: https://github.com/MarvellEmbeddedProcessors/atf-marvell, branch atf-v1.5-armada-18.12
U-Boot: https://github.com/MarvellEmbeddedProcessors/u-boot-marvell.git, branch u-boot-2018.03-armada-18.12

First the ATF's bl32.bin is built by compile_atf:

change into the ATF directory

ATF_TARGET_MAP (which is defined in config/sources/mvebu64.conf) is parsed - split by ; into three parts:

target_make: DEBUG=1 USE_COHERENT_MEM=0 LOG_LEVEL=20 SECURE=0 CLOCKSPRESET=CPU_800_DDR_800 DDR_TOPOLOGY=2 BOOTDEV=SPINOR PARTNUM=0 PLAT=a3700

target_patchdir: (empty)
target_files: build/a3700/debug/bl31.bin

advanced_patch atf atf-mvebu64 espressobin $target_patchdir next mvebu64-espressobin-next, applies patches from:

patch/atf/atf-mvebu64/target_
patch/atf/atf-mvebu64/board_espressobin
patch/atf/atf-mvebu64/branch_next
patch/atf/atf-mvebu64

none of the directories exist, so no patches are applied for the Espressobin
make $target_make CROSS_COMPILE="$ATF_COMPILER"

ATF_COMPILER='aarch64-linux-gnu-' (see config/sources/mvebu64.conf)

atf_custom_postprocess from config/sources/mvebu64.conf is called

packages/blobs/espressobin/DDR_TOPOLOGY_*.txt is copied into cache/sources/marvell-tools/tim/ddr/ (that is in the marvell-tools - or A3700-utils-marvell - repo clone)

copy all $target_files - which, for the Espressobin, is just 1 file: build/a3700/debug/bl31.bin - into .tmp/atf-${LINUXFAMILY}-${BOARD}-${BRANCH} ... where it's magicaly found by compile_uboot, yay!

Then U-Boot is built by compile_uboot. It does:

change into U-Boot directory
UBOOT_TARGET_MAP is read (defined in config/sources/mvebu64.conf), and for each line the loop body is called:

for the Espressobin there is only one line in
UBOOT_TARGET_MAP and so the loop it executed just once with target = "DEVICE_TREE=armada-3720-espressobin ;;flash-image-*.bin"
target is split by ; into:

target_make: armada-3720-espressobin (luckily the trailing space seems to be dropped)
target_patchdir: (empty)
target_files: flash-image-*.bin

patches are applied by the advanced_patch machinery: advanced_patch "u-boot""$BOOTPATCHDIR""$BOARD""$target_patchdir""$BRANCH""${LINUXFAMILY}-${BOARD}-${BRANCH}"

BOOTPATCHDIR is u-boot-mvebu64 (lib/configuration.sh)
so this becomes: advanced_patch u-boot u-boot-mvebu64 espressobin "" next mvebu64-espressobin-next
patches are applies searched for in:

patch/u-boot/u-boot-mvebu64/target_
patch/u-boot/u-boot-mvebu64/board_espressobin
patch/u-boot/u-boot-mvebu64/branch_next
patch/u-boot/u-boot-mvebu64

only patch/u-boot/u-boot-mvebu64 exists and contains currently 1 patch

cp -Rv $atftempdir/*.bin .

this "recovers" the files built in the ATF step (bl31.bin) and copies them to the u-boot src dir

make U-Boot config: make $BOOTCONFIG CROSS_COMPILE="$CCACHE $UBOOT_COMPILER"

UBOOT_COMPILER="aarch64-linux-gnu-" (lib/configuration.sh)
BOOTCONFIG="mvebu_espressobin-88f3720_defconfig"

patch U-Boot config

set LOCALVERSION to "-armbian"
setU-Boot env to be stored on a mmc on ext4 in /boot/boot.env
build U-Boot: make $target_make $CTHREADS CROSS_COMPILE="$CCACHE $UBOOT_COMPILER"
target_make: DEVICE_TREE=armada-3720-espressobin
UBOOT_COMPILER="aarch64-linux-gnu-" (lib/configuration.sh)

uboot_custom_postprocess from config/sources/mvebu64.conf is called - this does the wrapping in ATF

change into the ATF source directory
builds for all combinations of:

clocks=( 600_600 800_800 1000_800 1200_750 )
topology=( 512m_1cs_0 512m_2cs_0 1g_2cs_2 1g_1cs_4 2g_2cs_2 1g_1cs_5 2g_2cs_6 )

*cs_5 or *cs_6 means DDR4, others are DDR3 (see here)

if you build just for one revision, then you need to pick one of the clocks and topology values, for example for the Espressobin V5_0_1 with 2GiB, 2 chips, the values seem to be:

clock: 1000_800
topology: 2g_2cs_2

DDR_TOPOLOGY is set to the suffix after the last _ in topology (e.g. "2")
CLOCKSPRESET is set to "CPU_${i%_*}_DDR_${i##*_}", e.g. CPU_1000_DDR_800
the actual ATF binaries are built: make MV_DDR_PATH=$SRC/cache/sources/marvell-ddr CROSS_COMPILE=$ATF1 DEBUG=1 USE_COHERENT_MEM=0 LOG_LEVEL=20 SECURE=0 CLOCKSPRESET=$CLOCKSPRESET DDR_TOPOLOGY=$DDR_TOPOLOGY BOOTDEV=SPINOR PARTNUM=0 PLAT=a3700 all fip BL33=$BL33 WTP=$SRC/cache/sources/marvell-tools $CTHREADS CROSS_CM3=$ATF2