Following on from where we left off, now let’s actually use FEL for the whole process, not just to get uboot loaded. In the last piece, once uboot was loaded, we used uboot+tftp to boot our openwrt ramdisk, but FEL can do it all in one hit, over usb, according to http://linux-sunxi.org/FEL/USBBoot#Booting_the_whole_system_over_USB_.28U-Boot_.2B_kernel_.2B_initramfs.29 and that’s way more useful on things that might not have an ethernet port onboard.

We basically just take our steps from the last one, and add them as options to the sunxi-fel tool.

First, we trim down our “my.env” file, as now it just needs to boot.


$ cat my-fel.cmd
setenv bootargs console=ttyS0,115200 earlyprintk
bootm $kernel_addr_r - $fdt_addr_r


Now, we convert that to the “scr” file that uboot will run magically.

$ tools/mkimage -C none -A arm -T script -d my-fel.cmd my-fel.scr


Now, use sunxi-fel with all the wonderful paths into the build guts of openwrt.

$ sunxi-fel uboot u-boot-sunxi-with-spl.bin write-with-progress 0x42000000 /home/karlp/src/openwrt-git/bin/targets/sunxi/cortexa7/openwrt-sunxi-cortexa7-sun8i-h3-nanopi-neo-initramfs-kernel.bin write 0x43000000 ~/src/openwrt-git/build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/linux-sunxi_cortexa7/linux-4.14.82/arch/arm/boot/dts/sun8i-h3-nanopi-neo.dtb write 0x43100000 my-fel.scr
100% [================================================] 4013 kB, 770.4 kB/s


Because openwrt’s buildroot builds us a nice kernel+ramdisk image out of the box, (well, if you select “ramdisk” in the image settings) we don’t need to write the uImage and rootfs separately as indicated on the http://linux-sunxi.org/FEL/USBBoot page.

For reference, the openwrt diffconfig to build this is just

$ ./scripts/diffconfig.sh
CONFIG_TARGET_sunxi=y
CONFIG_TARGET_sunxi_cortexa7=y
CONFIG_TARGET_sunxi_cortexa7_DEVICE_sun8i-h3-nanopi-neo=y
CONFIG_DEVEL=y
CONFIG_TARGET_INITRAMFS_COMPRESSION_NONE=y
CONFIG_TARGET_ROOTFS_INITRAMFS=y


Edit: See the next post to use just FEL via USB, (no cheating and using tftp afterwards like we do here)

(Very rough unformatted, just so I don’t lose it)

FriendlyARM NanoPi Duo2 is ~similar enough to a FriendlyARM NanoPi Neo to get started. Later, we’ll work on… later stuff.

I don’t want to go hacking around with sd cards and crap while I’m developing stuff, and FEL mode is great.

So… get a uboot built (2018.11 is what I tested) using “make nanopi_neo_defconfig” (You will almost definitely want to enable “Networking Support->Random ethaddr if unset”

Now, patch sunxi-fel: https://github.com/linux-sunxi/sunxi-tools/pull/117

Now, make an environment file with some helpers…. (you can do this by hand if you like)

#=uEnv
myvar=world
bootcmd=echo "Hello $myvar."
bootargs=console=ttyS0,115200 earlyprintk
serverip=192.168.3.6
resetserver=setenv serverip 192.168.3.6
loadkernel=tftp $kernel_addr_r build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/linux-sunxi_cortexa7//sun8i-h3-nanopi-neo-kernel.bin
loaddtb=tftp $fdt_addr_r build_dir/target-arm_cortex-a7+neon-vfpv4_musl_eabi/u-boot-nanopi_neo/u-boot-2018.05/arch/arm/dts/sun8i-h3-nanopi-neo.dtb
loaddisk=tftp $ramdisk_addr_r
# Running dhcp will reset serverip....
winning=run resetserver && run loadkernel && run loaddtb && bootm $kernel_addr_r - $fdt_addr_r

(the magic variables are reffered to at http://linux-sunxi.org/FEL/USBBoot#Booting_the_whole_system_over_USB_.28U-Boot_.2B_kernel_.2B_initramfs.29)
The magic trick of bootm $kernel_addr_r – $fdt_addr_r I got from extracting the openwrt sdcard image file, and reading the “boot.scr” file in the first partition.

Now, go and build openwrt master

Now, setup a dhcp/tftp server as appropriate for your network.

Now, use (patched) sunxi-fel (fixing udev perms if necessary):

sunxi-fel uboot u-boot-sunxi-with-spl.bin write 0x43100000 my.env


Now, on serial console, use uboot to dhcp an address and run stuff…


dhcp
(ctrl-c to abort the dumb attempts at autofinding an image)
run resetserver
run winning


Now, enjoy the fruits of a whole lot of people’s labour…..


=> bootm $kernel_addr_r - $fdt_addr_r
## Booting kernel from Legacy Image at 42000000 ...
Image Name: ARM OpenWrt Linux-4.14.82
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 4013368 Bytes = 3.8 MiB
Load Address: 40008000
Entry Point: 40008000
Verifying Checksum ... OK
## Flattened Device Tree blob at 43000000
Booting using the fdt blob at 0x43000000
EHCI failed to shut down host controller.
Loading Kernel Image ... OK
Loading Device Tree to 49ff9000, end 49fff4b7 ... OK

boring bootlog snipped, you know what they look like


From here, we need to move to a real separate device tree for the duo2, prepare to get the AP6212 module up and running, and handle how overlays/custom versions should be handled….