While waiting for my R7800 delivery I'm trying to compile LEDE image for it.
Basically only Adblock included on top of the base config for R7800.
Same config compiles ok for my WNDR3700.
Getting following error at the very end of whole compilation after which it fails.
WARNING: Image file /home/gram/r7800/source/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/linux-ipq806x/R7800-uImage is too big
 That R7800 compilation generates lede-ipq806x-vmlinux.elf image and the size 26M is huge compared to same WNDR3700 image of lede-ar71xx-generic-vmlinux.elf with 5M.
26683020 Nov 11 21:48 lede-ipq806x-vmlinux.elf
The stock firmware uses 17 blocks by 128k as max kernel size
It was made according to that on all netgear ipq806x devices. But now it comes to an understanding that higher kernel size is needed, but it is going to cause backwards compatibility issues - ppl won't be able to sysupgrade because of different partition layout.
If someone makes a workaround sysupgrade script that checks kernel part size and cuts sysupgrade image and pads it to different kernel and rootfs layout - then I guess it's good to push it upstream.