Comment 6 for bug 1701137

So I checked out the latest Ubuntu kernel (based on 4.12.8) and enabled the options as mentioned above, which leads to the (attached) diff against the config grabbed from here:
http://kernel.ubuntu.com/~kernel-ppa/config/artful/linux/4.12.0-12.13/arm64-config.flavour.generic

These options should comply with the Ubuntu .config rules as I understand them (=m whenever possible), but require an initramfs to boot (from SD card). Compiling in CONFIG_MMC_SUNXI and CONFIG_REGULATOR_FIXED_VOLTAGE allow to access the rootfs without modules (handy for bootstrapping).