[R3Mini] compile official firmware / uboot-source


i try to compile official firmware because i want to add usb and sideload-support to load mainline uboot where i try to add net-support too (i have a driver for the phy, but i need to find out how i can register the phys via devicetree in uboot…i guess i need a mdio-bus node below eth, but i guess mtk eth driver does not support it yet or i need some kind of glue layer for mdio).

i also found no u-boot-config or source specialized for r3 mini, can you give me pointers where i can search for? i see that linux-targets for r3mini for emmc and nand are added via target/linux/mediatek/image/mt7986.mk but this is only linux and no uboot or GPT-sheme…i hope uboot is not taken as binary from anywhere in the huge tree and i can reuse some parts in my uboot later.

bootloader-section in menuconfig is also empty so it looks like an external source is used…i found a 8000-uboot-mediatek patch, but the source (https://gerrit.mediatek.inc) listed there is not reachable.

my first build-attempt failed so i had to rebuilt with -j=1 V=s which takes much more longer and seems to make full rebuild…which shows this error for ipt2socks:

make[3]: Entering directory 'BPI-R3MINI-OPENWRT-V21.02.3/feeds/small/ipt2socks'
mkdir -p BPI-R3MINI-OPENWRT-V21.02.3/dl
SHELL= flock BPI-R3MINI-OPENWRT-V21.02.3/tmp/.ipt2socks-1.1.3.tar.gz.flock -c '  	BPI-R3MINI-OPENWRT-V21.02.3/scripts/download.pl "/media/data_ext/git/uboot/BPI-R3MINI-OPENWRT-V21.02.3/dl" "ipt2socks-1.1.3.tar.gz" "5279eb1cb7555cf9292423cc9f672dc43e6e214b3411a6df26a6a1cfa59d88b7" "" "https://codeload.github.com/zfl9/ipt2socks/tar.gz/v1.1.3?"    '
Hash of the local file ipt2socks-1.1.3.tar.gz does not match (file: 73a2498dc95934c225d358707e7f7d060b5ce81aa45260ada09cbd15207d27d1, requested: 5279eb1cb7555cf9292423cc9f672dc43e6e214b3411a6df26a6a1cfa59d88b7) - deleting download.
make[3]: *** [Makefile:47: BPI-R3MINI-OPENWRT-V21.02.3/dl/ipt2socks-1.1.3.tar.gz] Error 2
make[3]: Leaving directory 'BPI-R3MINI-OPENWRT-V21.02.3/feeds/small/ipt2socks'
time: package/feeds/small/ipt2socks/compile#0.11#0.05#0.15
    ERROR: package/feeds/small/ipt2socks failed to build.

edit: seems that immortalwrt has net-support in uboot already, so this seems to be the easiest part: